<?xml version="1.0" encoding="US-ASCII"?>
<!--XBRL Document Created with Wdesk from Workiva-->
<!-- -->
<link:linkbase xsi:schemaLocation="http://www.xbrl.org/2003/linkbase http://www.xbrl.org/2003/xbrl-linkbase-2003-12-31.xsd" xmlns:link="http://www.xbrl.org/2003/linkbase" xmlns:xbrldt="http://xbrl.org/2005/xbrldt" xmlns:xlink="http://www.w3.org/1999/xlink" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
  <link:roleRef roleURI="http://www.ophthotech.com/role/Business" xlink:href="opht-20190331.xsd#Business" xlink:type="simple" />
  <link:roleRef roleURI="http://www.ophthotech.com/role/CashCashEquivalentsAndAvailableForSaleSecurities" xlink:href="opht-20190331.xsd#CashCashEquivalentsAndAvailableForSaleSecurities" xlink:type="simple" />
  <link:roleRef roleURI="http://www.ophthotech.com/role/CashCashEquivalentsAndAvailableForSaleSecuritiesDetails" xlink:href="opht-20190331.xsd#CashCashEquivalentsAndAvailableForSaleSecuritiesDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.ophthotech.com/role/CommitmentsAndContingencies" xlink:href="opht-20190331.xsd#CommitmentsAndContingencies" xlink:type="simple" />
  <link:roleRef roleURI="http://www.ophthotech.com/role/CommitmentsAndContingenciesDetails" xlink:href="opht-20190331.xsd#CommitmentsAndContingenciesDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.ophthotech.com/role/DocumentAndEntityInformation" xlink:href="opht-20190331.xsd#DocumentAndEntityInformation" xlink:type="simple" />
  <link:roleRef roleURI="http://www.ophthotech.com/role/FairValueMeasurements" xlink:href="opht-20190331.xsd#FairValueMeasurements" xlink:type="simple" />
  <link:roleRef roleURI="http://www.ophthotech.com/role/FairValueMeasurementsAssetsAndLiabilitiesMeasuredAtFairValueOnRecurringBasisDetails" xlink:href="opht-20190331.xsd#FairValueMeasurementsAssetsAndLiabilitiesMeasuredAtFairValueOnRecurringBasisDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.ophthotech.com/role/FairValueMeasurementsTables" xlink:href="opht-20190331.xsd#FairValueMeasurementsTables" xlink:type="simple" />
  <link:roleRef roleURI="http://www.ophthotech.com/role/IncomeTaxes" xlink:href="opht-20190331.xsd#IncomeTaxes" xlink:type="simple" />
  <link:roleRef roleURI="http://www.ophthotech.com/role/IncomeTaxesDetails" xlink:href="opht-20190331.xsd#IncomeTaxesDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.ophthotech.com/role/NetLossPerCommonShare" xlink:href="opht-20190331.xsd#NetLossPerCommonShare" xlink:type="simple" />
  <link:roleRef roleURI="http://www.ophthotech.com/role/NetLossPerCommonShareDetails" xlink:href="opht-20190331.xsd#NetLossPerCommonShareDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.ophthotech.com/role/NetLossPerCommonShareTables" xlink:href="opht-20190331.xsd#NetLossPerCommonShareTables" xlink:type="simple" />
  <link:roleRef roleURI="http://www.ophthotech.com/role/OperatingLeases" xlink:href="opht-20190331.xsd#OperatingLeases" xlink:type="simple" />
  <link:roleRef roleURI="http://www.ophthotech.com/role/OperatingLeasesNarrativeDetails" xlink:href="opht-20190331.xsd#OperatingLeasesNarrativeDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.ophthotech.com/role/OperatingLeasesScheduleOfOperatingLeaseLiabilityMaturityDetails" xlink:href="opht-20190331.xsd#OperatingLeasesScheduleOfOperatingLeaseLiabilityMaturityDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.ophthotech.com/role/OperatingLeasesTables" xlink:href="opht-20190331.xsd#OperatingLeasesTables" xlink:type="simple" />
  <link:roleRef roleURI="http://www.ophthotech.com/role/ShareBasedCompensation" xlink:href="opht-20190331.xsd#ShareBasedCompensation" xlink:type="simple" />
  <link:roleRef roleURI="http://www.ophthotech.com/role/ShareBasedCompensationNarrativeDetails" xlink:href="opht-20190331.xsd#ShareBasedCompensationNarrativeDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.ophthotech.com/role/ShareBasedCompensationSummaryOfOutstandingRsuAwardsGrantedDetails" xlink:href="opht-20190331.xsd#ShareBasedCompensationSummaryOfOutstandingRsuAwardsGrantedDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.ophthotech.com/role/ShareBasedCompensationSummaryOfShareBasedCompensationExpenseByAwardTypeDetails" xlink:href="opht-20190331.xsd#ShareBasedCompensationSummaryOfShareBasedCompensationExpenseByAwardTypeDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.ophthotech.com/role/ShareBasedCompensationSummaryOfShareBasedCompensationExpenseByFinancialStatementLineDetails" xlink:href="opht-20190331.xsd#ShareBasedCompensationSummaryOfShareBasedCompensationExpenseByFinancialStatementLineDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.ophthotech.com/role/ShareBasedCompensationSummaryOfStockOptionActivityDetails" xlink:href="opht-20190331.xsd#ShareBasedCompensationSummaryOfStockOptionActivityDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.ophthotech.com/role/ShareBasedCompensationTables" xlink:href="opht-20190331.xsd#ShareBasedCompensationTables" xlink:type="simple" />
  <link:roleRef roleURI="http://www.ophthotech.com/role/SubsequentEvent" xlink:href="opht-20190331.xsd#SubsequentEvent" xlink:type="simple" />
  <link:roleRef roleURI="http://www.ophthotech.com/role/SubsequentEventDetails" xlink:href="opht-20190331.xsd#SubsequentEventDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.ophthotech.com/role/SummaryOfSignificantAccountingPolicies" xlink:href="opht-20190331.xsd#SummaryOfSignificantAccountingPolicies" xlink:type="simple" />
  <link:roleRef roleURI="http://www.ophthotech.com/role/SummaryOfSignificantAccountingPoliciesCashAndCashEquivalentsDetails" xlink:href="opht-20190331.xsd#SummaryOfSignificantAccountingPoliciesCashAndCashEquivalentsDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.ophthotech.com/role/SummaryOfSignificantAccountingPoliciesPolicies" xlink:href="opht-20190331.xsd#SummaryOfSignificantAccountingPoliciesPolicies" xlink:type="simple" />
  <link:roleRef roleURI="http://www.ophthotech.com/role/SummaryOfSignificantAccountingPoliciesPropertyAndEquipmentDetails" xlink:href="opht-20190331.xsd#SummaryOfSignificantAccountingPoliciesPropertyAndEquipmentDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.ophthotech.com/role/SummaryOfSignificantAccountingPoliciesRecentlyAdoptedAccountingPronouncementsDetails" xlink:href="opht-20190331.xsd#SummaryOfSignificantAccountingPoliciesRecentlyAdoptedAccountingPronouncementsDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.ophthotech.com/role/SummaryOfSignificantAccountingPoliciesScheduleOfWeightedAverageAssumptionsDetails" xlink:href="opht-20190331.xsd#SummaryOfSignificantAccountingPoliciesScheduleOfWeightedAverageAssumptionsDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.ophthotech.com/role/SummaryOfSignificantAccountingPoliciesSegmentAndGeographicInformationDetails" xlink:href="opht-20190331.xsd#SummaryOfSignificantAccountingPoliciesSegmentAndGeographicInformationDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.ophthotech.com/role/SummaryOfSignificantAccountingPoliciesShareBasedCompensationDetails" xlink:href="opht-20190331.xsd#SummaryOfSignificantAccountingPoliciesShareBasedCompensationDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.ophthotech.com/role/SummaryOfSignificantAccountingPoliciesTables" xlink:href="opht-20190331.xsd#SummaryOfSignificantAccountingPoliciesTables" xlink:type="simple" />
  <link:roleRef roleURI="http://www.ophthotech.com/role/UnauditedConsolidatedBalanceSheets" xlink:href="opht-20190331.xsd#UnauditedConsolidatedBalanceSheets" xlink:type="simple" />
  <link:roleRef roleURI="http://www.ophthotech.com/role/UnauditedConsolidatedBalanceSheetsParenthetical" xlink:href="opht-20190331.xsd#UnauditedConsolidatedBalanceSheetsParenthetical" xlink:type="simple" />
  <link:roleRef roleURI="http://www.ophthotech.com/role/UnauditedConsolidatedStatementsOfCashFlows" xlink:href="opht-20190331.xsd#UnauditedConsolidatedStatementsOfCashFlows" xlink:type="simple" />
  <link:roleRef roleURI="http://www.ophthotech.com/role/UnauditedConsolidatedStatementsOfOperationsAndComprehensiveLoss" xlink:href="opht-20190331.xsd#UnauditedConsolidatedStatementsOfOperationsAndComprehensiveLoss" xlink:type="simple" />
  <link:roleRef roleURI="http://www.ophthotech.com/role/UnauditedConsolidatedStatementsOfStockholdersEquity" xlink:href="opht-20190331.xsd#UnauditedConsolidatedStatementsOfStockholdersEquity" xlink:type="simple" />
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/all" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#all" xlink:type="simple" />
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#dimension-default" xlink:type="simple" />
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#dimension-domain" xlink:type="simple" />
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/domain-member" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#domain-member" xlink:type="simple" />
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#hypercube-dimension" xlink:type="simple" />
  <link:definitionLink xlink:role="http://www.ophthotech.com/role/Business" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.ophthotech.com/role/CashCashEquivalentsAndAvailableForSaleSecurities" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.ophthotech.com/role/CashCashEquivalentsAndAvailableForSaleSecuritiesDetails" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.ophthotech.com/role/CommitmentsAndContingencies" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.ophthotech.com/role/CommitmentsAndContingenciesDetails" xlink:type="extended">
    <link:loc xlink:href="opht-20190331.xsd#opht_CommitmentsAndContingenciesLineItems" xlink:label="loc_opht_CommitmentsAndContingenciesLineItems_419C0080E3E88DBAA0806ECC6187BBCB" xlink:type="locator" />
    <link:loc xlink:href="opht-20190331.xsd#opht_ScheduleOfCommitmentsAndContingenciesTable" xlink:label="loc_opht_ScheduleOfCommitmentsAndContingenciesTable_A6E8A9FE38A2CB688D356ECC617BDC94" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_opht_CommitmentsAndContingenciesLineItems_419C0080E3E88DBAA0806ECC6187BBCB" xlink:to="loc_opht_ScheduleOfCommitmentsAndContingenciesTable_A6E8A9FE38A2CB688D356ECC617BDC94" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="opht-20190331.xsd#opht_AssetAcquisitionAxis" xlink:label="loc_opht_AssetAcquisitionAxis_45AEA46A10EAF991C1BA6ECC617BAD2D" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_opht_ScheduleOfCommitmentsAndContingenciesTable_A6E8A9FE38A2CB688D356ECC617BDC94" xlink:to="loc_opht_AssetAcquisitionAxis_45AEA46A10EAF991C1BA6ECC617BAD2D" xlink:type="arc" />
    <link:loc xlink:href="opht-20190331.xsd#opht_AssetAcquisitionDomain" xlink:label="loc_opht_AssetAcquisitionDomain_7CFC17F1E7D364255FF66EE5B73DDC7F_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_opht_AssetAcquisitionAxis_45AEA46A10EAF991C1BA6ECC617BAD2D" xlink:to="loc_opht_AssetAcquisitionDomain_7CFC17F1E7D364255FF66EE5B73DDC7F_default" xlink:type="arc" />
    <link:loc xlink:href="opht-20190331.xsd#opht_AssetAcquisitionDomain" xlink:label="loc_opht_AssetAcquisitionDomain_7CFC17F1E7D364255FF66EE5B73DDC7F" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_opht_AssetAcquisitionAxis_45AEA46A10EAF991C1BA6ECC617BAD2D" xlink:to="loc_opht_AssetAcquisitionDomain_7CFC17F1E7D364255FF66EE5B73DDC7F" xlink:type="arc" />
    <link:loc xlink:href="opht-20190331.xsd#opht_Inception4Member" xlink:label="loc_opht_Inception4Member_AB2EEA7D82E5D9920C916ECC617B0341" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_opht_AssetAcquisitionDomain_7CFC17F1E7D364255FF66EE5B73DDC7F" xlink:to="loc_opht_Inception4Member_AB2EEA7D82E5D9920C916ECC617B0341" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ResearchAndDevelopmentArrangementContractToPerformForOthersByTypeAxis" xlink:label="loc_us-gaap_ResearchAndDevelopmentArrangementContractToPerformForOthersByTypeAxis_16D642CEBBC3E4568B7B6ECC61815E62" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_opht_ScheduleOfCommitmentsAndContingenciesTable_A6E8A9FE38A2CB688D356ECC617BDC94" xlink:to="loc_us-gaap_ResearchAndDevelopmentArrangementContractToPerformForOthersByTypeAxis_16D642CEBBC3E4568B7B6ECC61815E62" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ResearchAndDevelopmentArrangementContractToPerformForOthersTypeDomain" xlink:label="loc_us-gaap_ResearchAndDevelopmentArrangementContractToPerformForOthersTypeDomain_DA98807A8E50350DD4EA6ECC618172B0_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_ResearchAndDevelopmentArrangementContractToPerformForOthersByTypeAxis_16D642CEBBC3E4568B7B6ECC61815E62" xlink:to="loc_us-gaap_ResearchAndDevelopmentArrangementContractToPerformForOthersTypeDomain_DA98807A8E50350DD4EA6ECC618172B0_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ResearchAndDevelopmentArrangementContractToPerformForOthersTypeDomain" xlink:label="loc_us-gaap_ResearchAndDevelopmentArrangementContractToPerformForOthersTypeDomain_DA98807A8E50350DD4EA6ECC618172B0" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_ResearchAndDevelopmentArrangementContractToPerformForOthersByTypeAxis_16D642CEBBC3E4568B7B6ECC61815E62" xlink:to="loc_us-gaap_ResearchAndDevelopmentArrangementContractToPerformForOthersTypeDomain_DA98807A8E50350DD4EA6ECC618172B0" xlink:type="arc" />
    <link:loc xlink:href="opht-20190331.xsd#opht_RHOadRPLicenseAgreementMember" xlink:label="loc_opht_RHOadRPLicenseAgreementMember_2C179C45A333ABC9DEF26ECC6181B009" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ResearchAndDevelopmentArrangementContractToPerformForOthersTypeDomain_DA98807A8E50350DD4EA6ECC618172B0" xlink:to="loc_opht_RHOadRPLicenseAgreementMember_2C179C45A333ABC9DEF26ECC6181B009" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_TypeOfArrangementAxis" xlink:label="loc_us-gaap_TypeOfArrangementAxis_C40E331A6336BA0F20086ECC618211DF" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_opht_ScheduleOfCommitmentsAndContingenciesTable_A6E8A9FE38A2CB688D356ECC617BDC94" xlink:to="loc_us-gaap_TypeOfArrangementAxis_C40E331A6336BA0F20086ECC618211DF" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ArrangementsAndNonarrangementTransactionsMember" xlink:label="loc_us-gaap_ArrangementsAndNonarrangementTransactionsMember_392FC20A0F798073165E6ECC6182A0F5_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_TypeOfArrangementAxis_C40E331A6336BA0F20086ECC618211DF" xlink:to="loc_us-gaap_ArrangementsAndNonarrangementTransactionsMember_392FC20A0F798073165E6ECC6182A0F5_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ArrangementsAndNonarrangementTransactionsMember" xlink:label="loc_us-gaap_ArrangementsAndNonarrangementTransactionsMember_392FC20A0F798073165E6ECC6182A0F5" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_TypeOfArrangementAxis_C40E331A6336BA0F20086ECC618211DF" xlink:to="loc_us-gaap_ArrangementsAndNonarrangementTransactionsMember_392FC20A0F798073165E6ECC6182A0F5" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_LicenseAgreementTermsMember" xlink:label="loc_us-gaap_LicenseAgreementTermsMember_5239907FD6B6741FCBE36ECC6182561A" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ArrangementsAndNonarrangementTransactionsMember_392FC20A0F798073165E6ECC6182A0F5" xlink:to="loc_us-gaap_LicenseAgreementTermsMember_5239907FD6B6741FCBE36ECC6182561A" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2018/elts/srt-2018-01-31.xsd#srt_CounterpartyNameAxis" xlink:label="loc_srt_CounterpartyNameAxis_F4C1C65490D1852334436ECC618284AE" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_opht_ScheduleOfCommitmentsAndContingenciesTable_A6E8A9FE38A2CB688D356ECC617BDC94" xlink:to="loc_srt_CounterpartyNameAxis_F4C1C65490D1852334436ECC618284AE" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2018/elts/srt-2018-01-31.xsd#srt_RepurchaseAgreementCounterpartyNameDomain" xlink:label="loc_srt_RepurchaseAgreementCounterpartyNameDomain_1CD8995BD6BB08FE4BC66ECC61822A0A_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_CounterpartyNameAxis_F4C1C65490D1852334436ECC618284AE" xlink:to="loc_srt_RepurchaseAgreementCounterpartyNameDomain_1CD8995BD6BB08FE4BC66ECC61822A0A_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2018/elts/srt-2018-01-31.xsd#srt_RepurchaseAgreementCounterpartyNameDomain" xlink:label="loc_srt_RepurchaseAgreementCounterpartyNameDomain_1CD8995BD6BB08FE4BC66ECC61822A0A" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_CounterpartyNameAxis_F4C1C65490D1852334436ECC618284AE" xlink:to="loc_srt_RepurchaseAgreementCounterpartyNameDomain_1CD8995BD6BB08FE4BC66ECC61822A0A" xlink:type="arc" />
    <link:loc xlink:href="opht-20190331.xsd#opht_ArchemixCorpMember" xlink:label="loc_opht_ArchemixCorpMember_3F71E7224AAA2381965B6ECC61838987" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RepurchaseAgreementCounterpartyNameDomain_1CD8995BD6BB08FE4BC66ECC61822A0A" xlink:to="loc_opht_ArchemixCorpMember_3F71E7224AAA2381965B6ECC61838987" xlink:type="arc" />
    <link:loc xlink:href="opht-20190331.xsd#opht_UniversityofFloridaResearchFoundationUFRFMember" xlink:label="loc_opht_UniversityofFloridaResearchFoundationUFRFMember_2C4E87794EF5751CAC686ECC6183DBBA" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RepurchaseAgreementCounterpartyNameDomain_1CD8995BD6BB08FE4BC66ECC61822A0A" xlink:to="loc_opht_UniversityofFloridaResearchFoundationUFRFMember_2C4E87794EF5751CAC686ECC6183DBBA" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2018/elts/srt-2018-01-31.xsd#srt_ProductOrServiceAxis" xlink:label="loc_srt_ProductOrServiceAxis_888609B23548DC5753136ECC61837B1D" xlink:type="locator" />
    <link:definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_opht_ScheduleOfCommitmentsAndContingenciesTable_A6E8A9FE38A2CB688D356ECC617BDC94" xlink:to="loc_srt_ProductOrServiceAxis_888609B23548DC5753136ECC61837B1D" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2018/elts/srt-2018-01-31.xsd#srt_ProductsAndServicesDomain" xlink:label="loc_srt_ProductsAndServicesDomain_8CB0F8A9140B68AFD2336ECC61831459_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ProductOrServiceAxis_888609B23548DC5753136ECC61837B1D" xlink:to="loc_srt_ProductsAndServicesDomain_8CB0F8A9140B68AFD2336ECC61831459_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2018/elts/srt-2018-01-31.xsd#srt_ProductsAndServicesDomain" xlink:label="loc_srt_ProductsAndServicesDomain_8CB0F8A9140B68AFD2336ECC61831459" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ProductOrServiceAxis_888609B23548DC5753136ECC61837B1D" xlink:to="loc_srt_ProductsAndServicesDomain_8CB0F8A9140B68AFD2336ECC61831459" xlink:type="arc" />
    <link:loc xlink:href="opht-20190331.xsd#opht_C5LicensedProductsMember" xlink:label="loc_opht_C5LicensedProductsMember_348E5302FC488DEA63496ECC6184D544" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_8CB0F8A9140B68AFD2336ECC61831459" xlink:to="loc_opht_C5LicensedProductsMember_348E5302FC488DEA63496ECC6184D544" xlink:type="arc" />
    <link:loc xlink:href="opht-20190331.xsd#opht_GAProductMember" xlink:label="loc_opht_GAProductMember_8138ECB10565956533356ECC61844E14" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_8CB0F8A9140B68AFD2336ECC61831459" xlink:to="loc_opht_GAProductMember_8138ECB10565956533356ECC61844E14" xlink:type="arc" />
    <link:loc xlink:href="opht-20190331.xsd#opht_WetAMDProductMember" xlink:label="loc_opht_WetAMDProductMember_2734532C0EDBD9E453E26ECC61841D07" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_8CB0F8A9140B68AFD2336ECC61831459" xlink:to="loc_opht_WetAMDProductMember_2734532C0EDBD9E453E26ECC61841D07" xlink:type="arc" />
    <link:loc xlink:href="opht-20190331.xsd#opht_MilestoneEventsAxis" xlink:label="loc_opht_MilestoneEventsAxis_09C3593CD207C2BE15A56ECC618486B2" xlink:type="locator" />
    <link:definitionArc order="6" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_opht_ScheduleOfCommitmentsAndContingenciesTable_A6E8A9FE38A2CB688D356ECC617BDC94" xlink:to="loc_opht_MilestoneEventsAxis_09C3593CD207C2BE15A56ECC618486B2" xlink:type="arc" />
    <link:loc xlink:href="opht-20190331.xsd#opht_MilestoneEventsDomain" xlink:label="loc_opht_MilestoneEventsDomain_9B251873CCC26F9863096ECC61858571_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_opht_MilestoneEventsAxis_09C3593CD207C2BE15A56ECC618486B2" xlink:to="loc_opht_MilestoneEventsDomain_9B251873CCC26F9863096ECC61858571_default" xlink:type="arc" />
    <link:loc xlink:href="opht-20190331.xsd#opht_MilestoneEventsDomain" xlink:label="loc_opht_MilestoneEventsDomain_9B251873CCC26F9863096ECC61858571" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_opht_MilestoneEventsAxis_09C3593CD207C2BE15A56ECC618486B2" xlink:to="loc_opht_MilestoneEventsDomain_9B251873CCC26F9863096ECC61858571" xlink:type="arc" />
    <link:loc xlink:href="opht-20190331.xsd#opht_AchievementOfSpecifiedClinicalAndRegulatoryMilestonesMember" xlink:label="loc_opht_AchievementOfSpecifiedClinicalAndRegulatoryMilestonesMember_6DAC314D4C35B1AD11456ECC6185E9E0" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_opht_MilestoneEventsDomain_9B251873CCC26F9863096ECC61858571" xlink:to="loc_opht_AchievementOfSpecifiedClinicalAndRegulatoryMilestonesMember_6DAC314D4C35B1AD11456ECC6185E9E0" xlink:type="arc" />
    <link:loc xlink:href="opht-20190331.xsd#opht_FirstIndicationMember" xlink:label="loc_opht_FirstIndicationMember_B41E6B83EDD7D929E9C76ECC6185F0B7" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_opht_MilestoneEventsDomain_9B251873CCC26F9863096ECC61858571" xlink:to="loc_opht_FirstIndicationMember_B41E6B83EDD7D929E9C76ECC6185F0B7" xlink:type="arc" />
    <link:loc xlink:href="opht-20190331.xsd#opht_SecondandThirdIndicationMember" xlink:label="loc_opht_SecondandThirdIndicationMember_E62A45E9F7C0AB2C25226ECC61852B49" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_opht_MilestoneEventsDomain_9B251873CCC26F9863096ECC61858571" xlink:to="loc_opht_SecondandThirdIndicationMember_E62A45E9F7C0AB2C25226ECC61852B49" xlink:type="arc" />
    <link:loc xlink:href="opht-20190331.xsd#opht_SustainedDeliveryApplicationsMember" xlink:label="loc_opht_SustainedDeliveryApplicationsMember_64A1C2FA3CDB1590F64D6ECC618551F0" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_opht_MilestoneEventsDomain_9B251873CCC26F9863096ECC61858571" xlink:to="loc_opht_SustainedDeliveryApplicationsMember_64A1C2FA3CDB1590F64D6ECC618551F0" xlink:type="arc" />
    <link:loc xlink:href="opht-20190331.xsd#opht_AchievementOfSpecifiedCommercialMilestonesMember" xlink:label="loc_opht_AchievementOfSpecifiedCommercialMilestonesMember_EDE9B7CEDD8E9CD042AF6ECC6186E272" xlink:type="locator" />
    <link:definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_opht_MilestoneEventsDomain_9B251873CCC26F9863096ECC61858571" xlink:to="loc_opht_AchievementOfSpecifiedCommercialMilestonesMember_EDE9B7CEDD8E9CD042AF6ECC6186E272" xlink:type="arc" />
    <link:loc xlink:href="opht-20190331.xsd#opht_SpecifiedClinicalMarketingApprovalandReimbursementApprovalMilestonesRelatedtoaLicensedProductMember" xlink:label="loc_opht_SpecifiedClinicalMarketingApprovalandReimbursementApprovalMilestonesRelatedtoaLicensedProductMember_791DA9A7157ED44F6CA96ECC6186C6C2" xlink:type="locator" />
    <link:definitionArc order="6" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_opht_MilestoneEventsDomain_9B251873CCC26F9863096ECC61858571" xlink:to="loc_opht_SpecifiedClinicalMarketingApprovalandReimbursementApprovalMilestonesRelatedtoaLicensedProductMember_791DA9A7157ED44F6CA96ECC6186C6C2" xlink:type="arc" />
    <link:loc xlink:href="opht-20190331.xsd#opht_SpecifiedCommercialSalesMilestonesRelatedtoaLicensedProductMember" xlink:label="loc_opht_SpecifiedCommercialSalesMilestonesRelatedtoaLicensedProductMember_F8916F3D5EB85ADE192C6ECC6186EB16" xlink:type="locator" />
    <link:definitionArc order="7" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_opht_MilestoneEventsDomain_9B251873CCC26F9863096ECC61858571" xlink:to="loc_opht_SpecifiedCommercialSalesMilestonesRelatedtoaLicensedProductMember_F8916F3D5EB85ADE192C6ECC6186EB16" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2018/elts/srt-2018-01-31.xsd#srt_RangeAxis" xlink:label="loc_srt_RangeAxis_4365F2B3D834DF36AF276ECC61869C52" xlink:type="locator" />
    <link:definitionArc order="7" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_opht_ScheduleOfCommitmentsAndContingenciesTable_A6E8A9FE38A2CB688D356ECC617BDC94" xlink:to="loc_srt_RangeAxis_4365F2B3D834DF36AF276ECC61869C52" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2018/elts/srt-2018-01-31.xsd#srt_RangeMember" xlink:label="loc_srt_RangeMember_94A4465B2FE7952CD4246ECC618668F1_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_RangeAxis_4365F2B3D834DF36AF276ECC61869C52" xlink:to="loc_srt_RangeMember_94A4465B2FE7952CD4246ECC618668F1_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2018/elts/srt-2018-01-31.xsd#srt_RangeMember" xlink:label="loc_srt_RangeMember_94A4465B2FE7952CD4246ECC618668F1" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_RangeAxis_4365F2B3D834DF36AF276ECC61869C52" xlink:to="loc_srt_RangeMember_94A4465B2FE7952CD4246ECC618668F1" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2018/elts/srt-2018-01-31.xsd#srt_MaximumMember" xlink:label="loc_srt_MaximumMember_E926DB1F87611B4112FF6ECC618741A4" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_94A4465B2FE7952CD4246ECC618668F1" xlink:to="loc_srt_MaximumMember_E926DB1F87611B4112FF6ECC618741A4" xlink:type="arc" />
    <link:loc xlink:href="opht-20190331.xsd#opht_AmountToBePaidOnAchievementOfMilestone" xlink:label="loc_opht_AmountToBePaidOnAchievementOfMilestone_CAF5AE161B72BA7FD5526ECC6187EAD8" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_opht_CommitmentsAndContingenciesLineItems_419C0080E3E88DBAA0806ECC6187BBCB" xlink:to="loc_opht_AmountToBePaidOnAchievementOfMilestone_CAF5AE161B72BA7FD5526ECC6187EAD8" xlink:type="arc" />
    <link:loc xlink:href="opht-20190331.xsd#opht_AssetAcquisitionContingentConsiderationArrangementsRangeOfOutcomesValueHigh" xlink:label="loc_opht_AssetAcquisitionContingentConsiderationArrangementsRangeOfOutcomesValueHigh_ACF15F9F7B3DE7ECB4F96ECC6187B0D1" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_opht_CommitmentsAndContingenciesLineItems_419C0080E3E88DBAA0806ECC6187BBCB" xlink:to="loc_opht_AssetAcquisitionContingentConsiderationArrangementsRangeOfOutcomesValueHigh_ACF15F9F7B3DE7ECB4F96ECC6187B0D1" xlink:type="arc" />
    <link:loc xlink:href="opht-20190331.xsd#opht_AssetAcquisitionClinicalAndMarketingApprovalMilestones" xlink:label="loc_opht_AssetAcquisitionClinicalAndMarketingApprovalMilestones_C5DC4B84BA76ADC233D06ECC61872772" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_opht_CommitmentsAndContingenciesLineItems_419C0080E3E88DBAA0806ECC6187BBCB" xlink:to="loc_opht_AssetAcquisitionClinicalAndMarketingApprovalMilestones_C5DC4B84BA76ADC233D06ECC61872772" xlink:type="arc" />
    <link:loc xlink:href="opht-20190331.xsd#opht_AssetAcquisitionContingentConsiderationArrangementsRangeOfOutcomesSharesIssuableHigh" xlink:label="loc_opht_AssetAcquisitionContingentConsiderationArrangementsRangeOfOutcomesSharesIssuableHigh_3BBB3FB721149C3EC80B6ECC61889575" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_opht_CommitmentsAndContingenciesLineItems_419C0080E3E88DBAA0806ECC6187BBCB" xlink:to="loc_opht_AssetAcquisitionContingentConsiderationArrangementsRangeOfOutcomesSharesIssuableHigh_3BBB3FB721149C3EC80B6ECC61889575" xlink:type="arc" />
    <link:loc xlink:href="opht-20190331.xsd#opht_AssetAcquisitionContingentConsiderationArrangementsContingentlyIssuableSharesAsAPercentageOfSharesOutstanding" xlink:label="loc_opht_AssetAcquisitionContingentConsiderationArrangementsContingentlyIssuableSharesAsAPercentageOfSharesOutstanding_A1FC06319B4F658BC0A46ECC6188C2C6" xlink:type="locator" />
    <link:definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_opht_CommitmentsAndContingenciesLineItems_419C0080E3E88DBAA0806ECC6187BBCB" xlink:to="loc_opht_AssetAcquisitionContingentConsiderationArrangementsContingentlyIssuableSharesAsAPercentageOfSharesOutstanding_A1FC06319B4F658BC0A46ECC6188C2C6" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_LitigationSettlementAmountAwardedToOtherParty" xlink:label="loc_us-gaap_LitigationSettlementAmountAwardedToOtherParty_34091BC59EDFB8A626C06ECC6188E181" xlink:type="locator" />
    <link:definitionArc order="6" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_opht_CommitmentsAndContingenciesLineItems_419C0080E3E88DBAA0806ECC6187BBCB" xlink:to="loc_us-gaap_LitigationSettlementAmountAwardedToOtherParty_34091BC59EDFB8A626C06ECC6188E181" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://www.ophthotech.com/role/DocumentAndEntityInformation" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.ophthotech.com/role/FairValueMeasurements" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.ophthotech.com/role/FairValueMeasurementsAssetsAndLiabilitiesMeasuredAtFairValueOnRecurringBasisDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems" xlink:label="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_8B878B595F9D3B3701A49832F90B584E" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable" xlink:label="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_B9FFBACFB0A7FE23A7099832F90814C8" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_8B878B595F9D3B3701A49832F90B584E" xlink:to="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_B9FFBACFB0A7FE23A7099832F90814C8" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FairValueByMeasurementFrequencyAxis" xlink:label="loc_us-gaap_FairValueByMeasurementFrequencyAxis_08699DEBFBA579CAF4169832F908DB0C" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_B9FFBACFB0A7FE23A7099832F90814C8" xlink:to="loc_us-gaap_FairValueByMeasurementFrequencyAxis_08699DEBFBA579CAF4169832F908DB0C" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FairValueMeasurementFrequencyDomain" xlink:label="loc_us-gaap_FairValueMeasurementFrequencyDomain_124B3D5B9E206DDB84A29832F90880C9_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByMeasurementFrequencyAxis_08699DEBFBA579CAF4169832F908DB0C" xlink:to="loc_us-gaap_FairValueMeasurementFrequencyDomain_124B3D5B9E206DDB84A29832F90880C9_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FairValueMeasurementFrequencyDomain" xlink:label="loc_us-gaap_FairValueMeasurementFrequencyDomain_124B3D5B9E206DDB84A29832F90880C9" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByMeasurementFrequencyAxis_08699DEBFBA579CAF4169832F908DB0C" xlink:to="loc_us-gaap_FairValueMeasurementFrequencyDomain_124B3D5B9E206DDB84A29832F90880C9" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FairValueMeasurementsRecurringMember" xlink:label="loc_us-gaap_FairValueMeasurementsRecurringMember_3DF91E5F945B940D058C9832F909D094" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementFrequencyDomain_124B3D5B9E206DDB84A29832F90880C9" xlink:to="loc_us-gaap_FairValueMeasurementsRecurringMember_3DF91E5F945B940D058C9832F909D094" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FairValueByFairValueHierarchyLevelAxis" xlink:label="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_5571819F22A8E748A3549832F909D5FA" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_B9FFBACFB0A7FE23A7099832F90814C8" xlink:to="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_5571819F22A8E748A3549832F909D5FA" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_89EBDE906AEC07993F939832F9096F47_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_5571819F22A8E748A3549832F909D5FA" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_89EBDE906AEC07993F939832F9096F47_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_89EBDE906AEC07993F939832F9096F47" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_5571819F22A8E748A3549832F909D5FA" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_89EBDE906AEC07993F939832F9096F47" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FairValueInputsLevel1Member" xlink:label="loc_us-gaap_FairValueInputsLevel1Member_1C8B0875EE6CD0312E2B9832F9091CB9" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_89EBDE906AEC07993F939832F9096F47" xlink:to="loc_us-gaap_FairValueInputsLevel1Member_1C8B0875EE6CD0312E2B9832F9091CB9" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FairValueInputsLevel2Member" xlink:label="loc_us-gaap_FairValueInputsLevel2Member_BB5752A780DA760D5A3C9832F90AE18D" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_89EBDE906AEC07993F939832F9096F47" xlink:to="loc_us-gaap_FairValueInputsLevel2Member_BB5752A780DA760D5A3C9832F90AE18D" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FairValueInputsLevel3Member" xlink:label="loc_us-gaap_FairValueInputsLevel3Member_F208AD7C6C8E6A22CEA49832F90A226E" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_89EBDE906AEC07993F939832F9096F47" xlink:to="loc_us-gaap_FairValueInputsLevel3Member_F208AD7C6C8E6A22CEA49832F90A226E" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FairValueByAssetClassAxis" xlink:label="loc_us-gaap_FairValueByAssetClassAxis_007C3737820070B482E29832F90AB972" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_B9FFBACFB0A7FE23A7099832F90814C8" xlink:to="loc_us-gaap_FairValueByAssetClassAxis_007C3737820070B482E29832F90AB972" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationByAssetClassDomain" xlink:label="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationByAssetClassDomain_8E95C9C2325F293961869832F90AA0C2_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByAssetClassAxis_007C3737820070B482E29832F90AB972" xlink:to="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationByAssetClassDomain_8E95C9C2325F293961869832F90AA0C2_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationByAssetClassDomain" xlink:label="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationByAssetClassDomain_8E95C9C2325F293961869832F90AA0C2" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByAssetClassAxis_007C3737820070B482E29832F90AB972" xlink:to="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationByAssetClassDomain_8E95C9C2325F293961869832F90AA0C2" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_MoneyMarketFundsMember" xlink:label="loc_us-gaap_MoneyMarketFundsMember_8F67E735A0C3B3B9B0639832F90B3DD2" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationByAssetClassDomain_8E95C9C2325F293961869832F90AA0C2" xlink:to="loc_us-gaap_MoneyMarketFundsMember_8F67E735A0C3B3B9B0639832F90B3DD2" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_CorporateDebtSecuritiesMember" xlink:label="loc_us-gaap_CorporateDebtSecuritiesMember_A98BD03F8BE660EA23769832F90B0D73" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationByAssetClassDomain_8E95C9C2325F293961869832F90AA0C2" xlink:to="loc_us-gaap_CorporateDebtSecuritiesMember_A98BD03F8BE660EA23769832F90B0D73" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_CashAndCashEquivalentsFairValueDisclosure" xlink:label="loc_us-gaap_CashAndCashEquivalentsFairValueDisclosure_2A80729237CF629D07FA9832F90BB117" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_8B878B595F9D3B3701A49832F90B584E" xlink:to="loc_us-gaap_CashAndCashEquivalentsFairValueDisclosure_2A80729237CF629D07FA9832F90BB117" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_AvailableForSaleSecuritiesDebtSecurities" xlink:label="loc_us-gaap_AvailableForSaleSecuritiesDebtSecurities_C8BA2310D8996C6D1AC49832F90BE1B6" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_8B878B595F9D3B3701A49832F90B584E" xlink:to="loc_us-gaap_AvailableForSaleSecuritiesDebtSecurities_C8BA2310D8996C6D1AC49832F90BE1B6" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FairValueAssetsLevel1ToLevel2TransfersAmount" xlink:label="loc_us-gaap_FairValueAssetsLevel1ToLevel2TransfersAmount_67C264AB1360D2F663239832F90C57E7" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_8B878B595F9D3B3701A49832F90B584E" xlink:to="loc_us-gaap_FairValueAssetsLevel1ToLevel2TransfersAmount_67C264AB1360D2F663239832F90C57E7" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://www.ophthotech.com/role/FairValueMeasurementsTables" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.ophthotech.com/role/IncomeTaxes" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.ophthotech.com/role/IncomeTaxesDetails" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.ophthotech.com/role/NetLossPerCommonShare" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.ophthotech.com/role/NetLossPerCommonShareDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareLineItems" xlink:label="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareLineItems_C9D4B483B6BF273FF46A8FF8AA1D0963" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ScheduleOfAntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareTable" xlink:label="loc_us-gaap_ScheduleOfAntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareTable_F4B498A19185B4EFC4E48FF8AA1CB7BA" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareLineItems_C9D4B483B6BF273FF46A8FF8AA1D0963" xlink:to="loc_us-gaap_ScheduleOfAntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareTable_F4B498A19185B4EFC4E48FF8AA1CB7BA" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis" xlink:label="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis_F069F71B2CD675C8C2D58FF8AA1CC892" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfAntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareTable_F4B498A19185B4EFC4E48FF8AA1CB7BA" xlink:to="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis_F069F71B2CD675C8C2D58FF8AA1CC892" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_AntidilutiveSecuritiesNameDomain" xlink:label="loc_us-gaap_AntidilutiveSecuritiesNameDomain_F16C409BD2DD15A2BF888FF8AA1CAA51_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis_F069F71B2CD675C8C2D58FF8AA1CC892" xlink:to="loc_us-gaap_AntidilutiveSecuritiesNameDomain_F16C409BD2DD15A2BF888FF8AA1CAA51_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_AntidilutiveSecuritiesNameDomain" xlink:label="loc_us-gaap_AntidilutiveSecuritiesNameDomain_F16C409BD2DD15A2BF888FF8AA1CAA51" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis_F069F71B2CD675C8C2D58FF8AA1CC892" xlink:to="loc_us-gaap_AntidilutiveSecuritiesNameDomain_F16C409BD2DD15A2BF888FF8AA1CAA51" xlink:type="arc" />
    <link:loc xlink:href="opht-20190331.xsd#opht_EmployeeAndNonemployeeStockOptionMember" xlink:label="loc_opht_EmployeeAndNonemployeeStockOptionMember_7C837D7059050F2EF9618FF8AA1D3EE9" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AntidilutiveSecuritiesNameDomain_F16C409BD2DD15A2BF888FF8AA1CAA51" xlink:to="loc_opht_EmployeeAndNonemployeeStockOptionMember_7C837D7059050F2EF9618FF8AA1D3EE9" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_RestrictedStockMember" xlink:label="loc_us-gaap_RestrictedStockMember_ED376448D6095E34DC378FF8AA1D8DCC" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AntidilutiveSecuritiesNameDomain_F16C409BD2DD15A2BF888FF8AA1CAA51" xlink:to="loc_us-gaap_RestrictedStockMember_ED376448D6095E34DC378FF8AA1D8DCC" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount" xlink:label="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount_A440C5198D70AF33AF058FF8AA1DAC56" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareLineItems_C9D4B483B6BF273FF46A8FF8AA1D0963" xlink:to="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount_A440C5198D70AF33AF058FF8AA1DAC56" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://www.ophthotech.com/role/NetLossPerCommonShareTables" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.ophthotech.com/role/OperatingLeases" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.ophthotech.com/role/OperatingLeasesNarrativeDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_NewAccountingPronouncementsOrChangeInAccountingPrincipleLineItems" xlink:label="loc_us-gaap_NewAccountingPronouncementsOrChangeInAccountingPrincipleLineItems_64D2CF1FB1FEB910FF549027EAE91B74" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_NewAccountingPronouncementsOrChangeInAccountingPrincipleTable" xlink:label="loc_us-gaap_NewAccountingPronouncementsOrChangeInAccountingPrincipleTable_1AD0F6C708A4516FD8489027EAE8174E" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_NewAccountingPronouncementsOrChangeInAccountingPrincipleLineItems_64D2CF1FB1FEB910FF549027EAE91B74" xlink:to="loc_us-gaap_NewAccountingPronouncementsOrChangeInAccountingPrincipleTable_1AD0F6C708A4516FD8489027EAE8174E" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_AdjustmentsForNewAccountingPronouncementsAxis" xlink:label="loc_us-gaap_AdjustmentsForNewAccountingPronouncementsAxis_32B63E5710E87E9A91CF9027EAE8092D" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_NewAccountingPronouncementsOrChangeInAccountingPrincipleTable_1AD0F6C708A4516FD8489027EAE8174E" xlink:to="loc_us-gaap_AdjustmentsForNewAccountingPronouncementsAxis_32B63E5710E87E9A91CF9027EAE8092D" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_TypeOfAdoptionMember" xlink:label="loc_us-gaap_TypeOfAdoptionMember_9B4E5A7333A2B155E7BD9027EAE8E998_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AdjustmentsForNewAccountingPronouncementsAxis_32B63E5710E87E9A91CF9027EAE8092D" xlink:to="loc_us-gaap_TypeOfAdoptionMember_9B4E5A7333A2B155E7BD9027EAE8E998_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_TypeOfAdoptionMember" xlink:label="loc_us-gaap_TypeOfAdoptionMember_9B4E5A7333A2B155E7BD9027EAE8E998" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AdjustmentsForNewAccountingPronouncementsAxis_32B63E5710E87E9A91CF9027EAE8092D" xlink:to="loc_us-gaap_TypeOfAdoptionMember_9B4E5A7333A2B155E7BD9027EAE8E998" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_AccountingStandardsUpdate201602Member" xlink:label="loc_us-gaap_AccountingStandardsUpdate201602Member_39008D17A149971236B99027EAE9A68E" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TypeOfAdoptionMember_9B4E5A7333A2B155E7BD9027EAE8E998" xlink:to="loc_us-gaap_AccountingStandardsUpdate201602Member_39008D17A149971236B99027EAE9A68E" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_OperatingLeaseLiability" xlink:label="loc_us-gaap_OperatingLeaseLiability_7D5DD70961E55D88979E9027EAE98C93" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NewAccountingPronouncementsOrChangeInAccountingPrincipleLineItems_64D2CF1FB1FEB910FF549027EAE91B74" xlink:to="loc_us-gaap_OperatingLeaseLiability_7D5DD70961E55D88979E9027EAE98C93" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_OperatingLeaseRightOfUseAsset" xlink:label="loc_us-gaap_OperatingLeaseRightOfUseAsset_DDF4607FC10BE1DB81E69027EAEA0004" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NewAccountingPronouncementsOrChangeInAccountingPrincipleLineItems_64D2CF1FB1FEB910FF549027EAE91B74" xlink:to="loc_us-gaap_OperatingLeaseRightOfUseAsset_DDF4607FC10BE1DB81E69027EAEA0004" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_OperatingLeaseWeightedAverageDiscountRatePercent" xlink:label="loc_us-gaap_OperatingLeaseWeightedAverageDiscountRatePercent_D4225561651CBE16B6179027EAEAF724" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NewAccountingPronouncementsOrChangeInAccountingPrincipleLineItems_64D2CF1FB1FEB910FF549027EAE91B74" xlink:to="loc_us-gaap_OperatingLeaseWeightedAverageDiscountRatePercent_D4225561651CBE16B6179027EAEAF724" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_OperatingLeaseExpense" xlink:label="loc_us-gaap_OperatingLeaseExpense_DFD0D6AFFB4F2AC2EC189027EAEF1166" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NewAccountingPronouncementsOrChangeInAccountingPrincipleLineItems_64D2CF1FB1FEB910FF549027EAE91B74" xlink:to="loc_us-gaap_OperatingLeaseExpense_DFD0D6AFFB4F2AC2EC189027EAEF1166" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_OperatingLeasePayments" xlink:label="loc_us-gaap_OperatingLeasePayments_8E134A29533034214C4490287DDBC68E" xlink:type="locator" />
    <link:definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NewAccountingPronouncementsOrChangeInAccountingPrincipleLineItems_64D2CF1FB1FEB910FF549027EAE91B74" xlink:to="loc_us-gaap_OperatingLeasePayments_8E134A29533034214C4490287DDBC68E" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_OperatingLeaseWeightedAverageRemainingLeaseTerm1" xlink:label="loc_us-gaap_OperatingLeaseWeightedAverageRemainingLeaseTerm1_CE287F8E558F5B936DEC9027EAEFC5E8" xlink:type="locator" />
    <link:definitionArc order="6" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NewAccountingPronouncementsOrChangeInAccountingPrincipleLineItems_64D2CF1FB1FEB910FF549027EAE91B74" xlink:to="loc_us-gaap_OperatingLeaseWeightedAverageRemainingLeaseTerm1_CE287F8E558F5B936DEC9027EAEFC5E8" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://www.ophthotech.com/role/OperatingLeasesScheduleOfOperatingLeaseLiabilityMaturityDetails" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.ophthotech.com/role/OperatingLeasesTables" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.ophthotech.com/role/ShareBasedCompensation" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.ophthotech.com/role/ShareBasedCompensationNarrativeDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_4D892AC67E7F68EDDA986ECC620EF236" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable" xlink:label="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_AE19F6A345A65E3255EB6ECC620B6AF0" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_4D892AC67E7F68EDDA986ECC620EF236" xlink:to="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_AE19F6A345A65E3255EB6ECC620B6AF0" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_PlanNameAxis" xlink:label="loc_us-gaap_PlanNameAxis_662643A2064488C089BD6ECC620BF55B" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_AE19F6A345A65E3255EB6ECC620B6AF0" xlink:to="loc_us-gaap_PlanNameAxis_662643A2064488C089BD6ECC620BF55B" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_PlanNameDomain" xlink:label="loc_us-gaap_PlanNameDomain_33BBFB97F6F324FFABB36ECC620B2828_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_PlanNameAxis_662643A2064488C089BD6ECC620BF55B" xlink:to="loc_us-gaap_PlanNameDomain_33BBFB97F6F324FFABB36ECC620B2828_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_PlanNameDomain" xlink:label="loc_us-gaap_PlanNameDomain_33BBFB97F6F324FFABB36ECC620B2828" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_PlanNameAxis_662643A2064488C089BD6ECC620BF55B" xlink:to="loc_us-gaap_PlanNameDomain_33BBFB97F6F324FFABB36ECC620B2828" xlink:type="arc" />
    <link:loc xlink:href="opht-20190331.xsd#opht_StockIncentive2013PlanMember" xlink:label="loc_opht_StockIncentive2013PlanMember_49ED34F5806BB8136CB76ECC620C67AE" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PlanNameDomain_33BBFB97F6F324FFABB36ECC620B2828" xlink:to="loc_opht_StockIncentive2013PlanMember_49ED34F5806BB8136CB76ECC620C67AE" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_AwardTypeAxis" xlink:label="loc_us-gaap_AwardTypeAxis_650D73DCE649A25C3D4B6ECC620DF513" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_AE19F6A345A65E3255EB6ECC620B6AF0" xlink:to="loc_us-gaap_AwardTypeAxis_650D73DCE649A25C3D4B6ECC620DF513" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_3B91ACC1C2E8BC564FF86ECC620D3C0F_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AwardTypeAxis_650D73DCE649A25C3D4B6ECC620DF513" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_3B91ACC1C2E8BC564FF86ECC620D3C0F_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_3B91ACC1C2E8BC564FF86ECC620D3C0F" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AwardTypeAxis_650D73DCE649A25C3D4B6ECC620DF513" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_3B91ACC1C2E8BC564FF86ECC620D3C0F" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_EmployeeStockMember" xlink:label="loc_us-gaap_EmployeeStockMember_1B317D2A9AF40CE9C6E66ECC620D6C1C" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_3B91ACC1C2E8BC564FF86ECC620D3C0F" xlink:to="loc_us-gaap_EmployeeStockMember_1B317D2A9AF40CE9C6E66ECC620D6C1C" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_EmployeeStockOptionMember" xlink:label="loc_us-gaap_EmployeeStockOptionMember_AB49F14B3F41E52F99946ECC620E6DA9" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_3B91ACC1C2E8BC564FF86ECC620D3C0F" xlink:to="loc_us-gaap_EmployeeStockOptionMember_AB49F14B3F41E52F99946ECC620E6DA9" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_RestrictedStockMember" xlink:label="loc_us-gaap_RestrictedStockMember_A9D1810640C201251B656ECC620E1321" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_3B91ACC1C2E8BC564FF86ECC620D3C0F" xlink:to="loc_us-gaap_RestrictedStockMember_A9D1810640C201251B656ECC620E1321" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfAdditionalSharesAuthorized" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfAdditionalSharesAuthorized_F144AE85119B7C301E646ECC620E1CB7" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_4D892AC67E7F68EDDA986ECC620EF236" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfAdditionalSharesAuthorized_F144AE85119B7C301E646ECC620E1CB7" xlink:type="arc" />
    <link:loc xlink:href="opht-20190331.xsd#opht_ShareBasedCompensationArrangementByShareBasedPaymentAwardPercentageOfAnnualIncreaseInSharesReservedForIssuance" xlink:label="loc_opht_ShareBasedCompensationArrangementByShareBasedPaymentAwardPercentageOfAnnualIncreaseInSharesReservedForIssuance_EF60136C16A94C91C8EB6ECC620E50A6" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_4D892AC67E7F68EDDA986ECC620EF236" xlink:to="loc_opht_ShareBasedCompensationArrangementByShareBasedPaymentAwardPercentageOfAnnualIncreaseInSharesReservedForIssuance_EF60136C16A94C91C8EB6ECC620E50A6" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrant" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrant_8DA3BBED7F845412EBF96ECC620E73E6" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_4D892AC67E7F68EDDA986ECC620EF236" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrant_8DA3BBED7F845412EBF96ECC620E73E6" xlink:type="arc" />
    <link:loc xlink:href="opht-20190331.xsd#opht_ShareBasedCompensationArrangementBySharebasedPaymentAwardNumberOfSharesAvailableForFuturePurchase" xlink:label="loc_opht_ShareBasedCompensationArrangementBySharebasedPaymentAwardNumberOfSharesAvailableForFuturePurchase_03546F1695CE978484056ECC620F1D23" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_4D892AC67E7F68EDDA986ECC620EF236" xlink:to="loc_opht_ShareBasedCompensationArrangementBySharebasedPaymentAwardNumberOfSharesAvailableForFuturePurchase_03546F1695CE978484056ECC620F1D23" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedStockOptions" xlink:label="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedStockOptions_27CE666EC886BE50406D6ECC620F7396" xlink:type="locator" />
    <link:definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_4D892AC67E7F68EDDA986ECC620EF236" xlink:to="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedStockOptions_27CE666EC886BE50406D6ECC620F7396" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1" xlink:label="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1_B52597C31FA12C2C24486ECC620F9738" xlink:type="locator" />
    <link:definitionArc order="6" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_4D892AC67E7F68EDDA986ECC620EF236" xlink:to="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1_B52597C31FA12C2C24486ECC620F9738" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedShareBasedAwardsOtherThanOptions" xlink:label="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedShareBasedAwardsOtherThanOptions_813F4C1E5CF7066EE3E56ECC620FF583" xlink:type="locator" />
    <link:definitionArc order="7" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_4D892AC67E7F68EDDA986ECC620EF236" xlink:to="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedShareBasedAwardsOtherThanOptions_813F4C1E5CF7066EE3E56ECC620FF583" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodTotalFairValue" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodTotalFairValue_08D2D71ACB5D97E70E296ECC620FD493" xlink:type="locator" />
    <link:definitionArc order="8" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_4D892AC67E7F68EDDA986ECC620EF236" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodTotalFairValue_08D2D71ACB5D97E70E296ECC620FD493" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardSharesIssuedInPeriod" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardSharesIssuedInPeriod_EF189E2B34D04017DD666ECC620F54F9" xlink:type="locator" />
    <link:definitionArc order="9" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_4D892AC67E7F68EDDA986ECC620EF236" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardSharesIssuedInPeriod_EF189E2B34D04017DD666ECC620F54F9" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ProceedsFromStockPlans" xlink:label="loc_us-gaap_ProceedsFromStockPlans_9B6C1D3078F1F821C9B36ECC62106F78" xlink:type="locator" />
    <link:definitionArc order="10" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_4D892AC67E7F68EDDA986ECC620EF236" xlink:to="loc_us-gaap_ProceedsFromStockPlans_9B6C1D3078F1F821C9B36ECC62106F78" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://www.ophthotech.com/role/ShareBasedCompensationSummaryOfOutstandingRsuAwardsGrantedDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_071E1C45C79FDDB01E3B8FF8A9C06074" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable" xlink:label="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_5B2B9A253B9596C0A8128FF8A9BFF9BB" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_071E1C45C79FDDB01E3B8FF8A9C06074" xlink:to="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_5B2B9A253B9596C0A8128FF8A9BFF9BB" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_AwardTypeAxis" xlink:label="loc_us-gaap_AwardTypeAxis_11511EB45EEDC75E6CDE8FF8A9C04C45" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_5B2B9A253B9596C0A8128FF8A9BFF9BB" xlink:to="loc_us-gaap_AwardTypeAxis_11511EB45EEDC75E6CDE8FF8A9C04C45" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_25EC055126EADC53750A8FF8A9C0147A_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AwardTypeAxis_11511EB45EEDC75E6CDE8FF8A9C04C45" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_25EC055126EADC53750A8FF8A9C0147A_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_25EC055126EADC53750A8FF8A9C0147A" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AwardTypeAxis_11511EB45EEDC75E6CDE8FF8A9C04C45" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_25EC055126EADC53750A8FF8A9C0147A" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_RestrictedStockMember" xlink:label="loc_us-gaap_RestrictedStockMember_0096A2F25B604E5BEE178FF8A9C0F00B" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_25EC055126EADC53750A8FF8A9C0147A" xlink:to="loc_us-gaap_RestrictedStockMember_0096A2F25B604E5BEE178FF8A9C0F00B" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_82AAE501D479B9F988CB8FF8A9C00F43" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_071E1C45C79FDDB01E3B8FF8A9C06074" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_82AAE501D479B9F988CB8FF8A9C00F43" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber_67433DDA74FF906449D68FF8A9C12413" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_82AAE501D479B9F988CB8FF8A9C00F43" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber_67433DDA74FF906449D68FF8A9C12413" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod_A1C91808CBD465BC5FB59019AECE535C" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_82AAE501D479B9F988CB8FF8A9C00F43" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod_A1C91808CBD465BC5FB59019AECE535C" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod_7173F1B5DE2A9710A9CF8FF8A9C1594B" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_82AAE501D479B9F988CB8FF8A9C00F43" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod_7173F1B5DE2A9710A9CF8FF8A9C1594B" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod_34EE328A70E1215DB7D98FF8A9C1A767" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_82AAE501D479B9F988CB8FF8A9C00F43" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod_34EE328A70E1215DB7D98FF8A9C1A767" xlink:type="arc" />
    <link:loc xlink:href="opht-20190331.xsd#opht_ShareBasedCompensationArrangementBySharebasedPaymentAwardEquityInstrumentsOtherThanOptionsExpectedToVestNumber" xlink:label="loc_opht_ShareBasedCompensationArrangementBySharebasedPaymentAwardEquityInstrumentsOtherThanOptionsExpectedToVestNumber_FD844FEC437A0840662D8FF8A9C1F10E" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_071E1C45C79FDDB01E3B8FF8A9C06074" xlink:to="loc_opht_ShareBasedCompensationArrangementBySharebasedPaymentAwardEquityInstrumentsOtherThanOptionsExpectedToVestNumber_FD844FEC437A0840662D8FF8A9C1F10E" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_1864C2EE15166323AE4F8FF8A9C25377" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_071E1C45C79FDDB01E3B8FF8A9C06074" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_1864C2EE15166323AE4F8FF8A9C25377" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue_1CEA1882B48334E45FE68FF8A9C271FC" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_1864C2EE15166323AE4F8FF8A9C25377" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue_1CEA1882B48334E45FE68FF8A9C271FC" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue_E3FD95C4A8365CA8BBDD9015CBCEACD1" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_1864C2EE15166323AE4F8FF8A9C25377" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue_E3FD95C4A8365CA8BBDD9015CBCEACD1" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue_A70A0E6635E4E3C0234C8FF8A9C28B3A" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_1864C2EE15166323AE4F8FF8A9C25377" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue_A70A0E6635E4E3C0234C8FF8A9C28B3A" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeituresWeightedAverageGrantDateFairValue" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeituresWeightedAverageGrantDateFairValue_C1F486E10A811F0A8CFD8FF8A9C24E7F" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_1864C2EE15166323AE4F8FF8A9C25377" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeituresWeightedAverageGrantDateFairValue_C1F486E10A811F0A8CFD8FF8A9C24E7F" xlink:type="arc" />
    <link:loc xlink:href="opht-20190331.xsd#opht_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsExpectedToVestWeightedAverageGrantDateFairValue" xlink:label="loc_opht_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsExpectedToVestWeightedAverageGrantDateFairValue_38DF6F4D4FA7085CD2648FF8A9C30734" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_071E1C45C79FDDB01E3B8FF8A9C06074" xlink:to="loc_opht_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsExpectedToVestWeightedAverageGrantDateFairValue_38DF6F4D4FA7085CD2648FF8A9C30734" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://www.ophthotech.com/role/ShareBasedCompensationSummaryOfShareBasedCompensationExpenseByAwardTypeDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_E5F617CE8AE933B8308D4FC2FEA0BA61" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable" xlink:label="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_6C209F34B7AED8B5C6804FC2FE9CB03D" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_E5F617CE8AE933B8308D4FC2FEA0BA61" xlink:to="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_6C209F34B7AED8B5C6804FC2FE9CB03D" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_AwardTypeAxis" xlink:label="loc_us-gaap_AwardTypeAxis_1D5F735D914E6AD7F26A4FC2FE9DE6A3" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_6C209F34B7AED8B5C6804FC2FE9CB03D" xlink:to="loc_us-gaap_AwardTypeAxis_1D5F735D914E6AD7F26A4FC2FE9DE6A3" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_000B83011CAE840A6E8A4FC2FE9DAAE5_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AwardTypeAxis_1D5F735D914E6AD7F26A4FC2FE9DE6A3" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_000B83011CAE840A6E8A4FC2FE9DAAE5_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_000B83011CAE840A6E8A4FC2FE9DAAE5" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AwardTypeAxis_1D5F735D914E6AD7F26A4FC2FE9DE6A3" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_000B83011CAE840A6E8A4FC2FE9DAAE5" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_EmployeeStockOptionMember" xlink:label="loc_us-gaap_EmployeeStockOptionMember_B9AD096200A33A03FFAC4FC2FE9D8AFB" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_000B83011CAE840A6E8A4FC2FE9DAAE5" xlink:to="loc_us-gaap_EmployeeStockOptionMember_B9AD096200A33A03FFAC4FC2FE9D8AFB" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_RestrictedStockUnitsRSUMember" xlink:label="loc_us-gaap_RestrictedStockUnitsRSUMember_B06EFE8D571CB46EEA3B4FC2FE9E247D" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_000B83011CAE840A6E8A4FC2FE9DAAE5" xlink:to="loc_us-gaap_RestrictedStockUnitsRSUMember_B06EFE8D571CB46EEA3B4FC2FE9E247D" xlink:type="arc" />
    <link:loc xlink:href="opht-20190331.xsd#opht_StockIncentive2013PlanMember" xlink:label="loc_opht_StockIncentive2013PlanMember_47491350C975159EF67B4FC2FEA0511C" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_000B83011CAE840A6E8A4FC2FE9DAAE5" xlink:to="loc_opht_StockIncentive2013PlanMember_47491350C975159EF67B4FC2FEA0511C" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_AllocatedShareBasedCompensationExpense" xlink:label="loc_us-gaap_AllocatedShareBasedCompensationExpense_759E14B40F5479AA4EC74FC2FEA0EAD1" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_E5F617CE8AE933B8308D4FC2FEA0BA61" xlink:to="loc_us-gaap_AllocatedShareBasedCompensationExpense_759E14B40F5479AA4EC74FC2FEA0EAD1" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://www.ophthotech.com/role/ShareBasedCompensationSummaryOfShareBasedCompensationExpenseByFinancialStatementLineDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_EDD15B4114CC4252960A502E2F1FE943" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable" xlink:label="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_DC9D2669DB8CB9C2FAE2502E2F1D435E" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_EDD15B4114CC4252960A502E2F1FE943" xlink:to="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_DC9D2669DB8CB9C2FAE2502E2F1D435E" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_IncomeStatementLocationAxis" xlink:label="loc_us-gaap_IncomeStatementLocationAxis_100BF24E29FAC342EC66502E2F1E9135" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_DC9D2669DB8CB9C2FAE2502E2F1D435E" xlink:to="loc_us-gaap_IncomeStatementLocationAxis_100BF24E29FAC342EC66502E2F1E9135" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_IncomeStatementLocationDomain" xlink:label="loc_us-gaap_IncomeStatementLocationDomain_FDD047039CC6C24C3EA0502E2F1E00F4_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_IncomeStatementLocationAxis_100BF24E29FAC342EC66502E2F1E9135" xlink:to="loc_us-gaap_IncomeStatementLocationDomain_FDD047039CC6C24C3EA0502E2F1E00F4_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_IncomeStatementLocationDomain" xlink:label="loc_us-gaap_IncomeStatementLocationDomain_FDD047039CC6C24C3EA0502E2F1E00F4" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_IncomeStatementLocationAxis_100BF24E29FAC342EC66502E2F1E9135" xlink:to="loc_us-gaap_IncomeStatementLocationDomain_FDD047039CC6C24C3EA0502E2F1E00F4" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ResearchAndDevelopmentExpenseMember" xlink:label="loc_us-gaap_ResearchAndDevelopmentExpenseMember_9333B101A1D8678553FE502E2F1E0CD4" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementLocationDomain_FDD047039CC6C24C3EA0502E2F1E00F4" xlink:to="loc_us-gaap_ResearchAndDevelopmentExpenseMember_9333B101A1D8678553FE502E2F1E0CD4" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_GeneralAndAdministrativeExpenseMember" xlink:label="loc_us-gaap_GeneralAndAdministrativeExpenseMember_56BF01AAECC38EC700DB502E2F1F92C5" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementLocationDomain_FDD047039CC6C24C3EA0502E2F1E00F4" xlink:to="loc_us-gaap_GeneralAndAdministrativeExpenseMember_56BF01AAECC38EC700DB502E2F1F92C5" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_AllocatedShareBasedCompensationExpense" xlink:label="loc_us-gaap_AllocatedShareBasedCompensationExpense_7523FF457AE433A74C25502E2F2097FB" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_EDD15B4114CC4252960A502E2F1FE943" xlink:to="loc_us-gaap_AllocatedShareBasedCompensationExpense_7523FF457AE433A74C25502E2F2097FB" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://www.ophthotech.com/role/ShareBasedCompensationSummaryOfStockOptionActivityDetails" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.ophthotech.com/role/ShareBasedCompensationTables" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.ophthotech.com/role/SubsequentEvent" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.ophthotech.com/role/SubsequentEventDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_SubsequentEventLineItems" xlink:label="loc_us-gaap_SubsequentEventLineItems_F7C60F2F4AF2AC106C154F97B80F0143" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_SubsequentEventTable" xlink:label="loc_us-gaap_SubsequentEventTable_A71085BF68C8BE91512E4F97B80C54A4" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_SubsequentEventLineItems_F7C60F2F4AF2AC106C154F97B80F0143" xlink:to="loc_us-gaap_SubsequentEventTable_A71085BF68C8BE91512E4F97B80C54A4" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2018/elts/srt-2018-01-31.xsd#srt_ProductOrServiceAxis" xlink:label="loc_srt_ProductOrServiceAxis_3890D9870500656BC170500861DACB8F" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_SubsequentEventTable_A71085BF68C8BE91512E4F97B80C54A4" xlink:to="loc_srt_ProductOrServiceAxis_3890D9870500656BC170500861DACB8F" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2018/elts/srt-2018-01-31.xsd#srt_ProductsAndServicesDomain" xlink:label="loc_srt_ProductsAndServicesDomain_84E81989EA57D32C1E8A500861DBBA3D_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ProductOrServiceAxis_3890D9870500656BC170500861DACB8F" xlink:to="loc_srt_ProductsAndServicesDomain_84E81989EA57D32C1E8A500861DBBA3D_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2018/elts/srt-2018-01-31.xsd#srt_ProductsAndServicesDomain" xlink:label="loc_srt_ProductsAndServicesDomain_84E81989EA57D32C1E8A500861DBBA3D" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ProductOrServiceAxis_3890D9870500656BC170500861DACB8F" xlink:to="loc_srt_ProductsAndServicesDomain_84E81989EA57D32C1E8A500861DBBA3D" xlink:type="arc" />
    <link:loc xlink:href="opht-20190331.xsd#opht_PrimaryLicensedProductMember" xlink:label="loc_opht_PrimaryLicensedProductMember_1695997D16DBD193AAFB500998612315" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_84E81989EA57D32C1E8A500861DBBA3D" xlink:to="loc_opht_PrimaryLicensedProductMember_1695997D16DBD193AAFB500998612315" xlink:type="arc" />
    <link:loc xlink:href="opht-20190331.xsd#opht_OtherLicensedProductMember" xlink:label="loc_opht_OtherLicensedProductMember_D7763E044B8E81401620500A6D24A454" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_84E81989EA57D32C1E8A500861DBBA3D" xlink:to="loc_opht_OtherLicensedProductMember_D7763E044B8E81401620500A6D24A454" xlink:type="arc" />
    <link:loc xlink:href="opht-20190331.xsd#opht_MilestoneEventsAxis" xlink:label="loc_opht_MilestoneEventsAxis_9EA73C694021578CB6F44FDC0C2BDC68" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_SubsequentEventTable_A71085BF68C8BE91512E4F97B80C54A4" xlink:to="loc_opht_MilestoneEventsAxis_9EA73C694021578CB6F44FDC0C2BDC68" xlink:type="arc" />
    <link:loc xlink:href="opht-20190331.xsd#opht_MilestoneEventsDomain" xlink:label="loc_opht_MilestoneEventsDomain_2737C59B64B8C1EDF3024FDC0C2D487E_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_opht_MilestoneEventsAxis_9EA73C694021578CB6F44FDC0C2BDC68" xlink:to="loc_opht_MilestoneEventsDomain_2737C59B64B8C1EDF3024FDC0C2D487E_default" xlink:type="arc" />
    <link:loc xlink:href="opht-20190331.xsd#opht_MilestoneEventsDomain" xlink:label="loc_opht_MilestoneEventsDomain_2737C59B64B8C1EDF3024FDC0C2D487E" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_opht_MilestoneEventsAxis_9EA73C694021578CB6F44FDC0C2BDC68" xlink:to="loc_opht_MilestoneEventsDomain_2737C59B64B8C1EDF3024FDC0C2D487E" xlink:type="arc" />
    <link:loc xlink:href="opht-20190331.xsd#opht_SpecifiedClinicalMarketingApprovalandReimbursementApprovalMilestonesRelatedtoaLicensedProductMember" xlink:label="loc_opht_SpecifiedClinicalMarketingApprovalandReimbursementApprovalMilestonesRelatedtoaLicensedProductMember_AD129C21C9E30042043A50075E5883C5" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_opht_MilestoneEventsDomain_2737C59B64B8C1EDF3024FDC0C2D487E" xlink:to="loc_opht_SpecifiedClinicalMarketingApprovalandReimbursementApprovalMilestonesRelatedtoaLicensedProductMember_AD129C21C9E30042043A50075E5883C5" xlink:type="arc" />
    <link:loc xlink:href="opht-20190331.xsd#opht_SpecifiedCommercialSalesMilestonesRelatedtoaLicensedProductMember" xlink:label="loc_opht_SpecifiedCommercialSalesMilestonesRelatedtoaLicensedProductMember_3A5C52D768958844ECD6500BD38716C7" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_opht_MilestoneEventsDomain_2737C59B64B8C1EDF3024FDC0C2D487E" xlink:to="loc_opht_SpecifiedCommercialSalesMilestonesRelatedtoaLicensedProductMember_3A5C52D768958844ECD6500BD38716C7" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ResearchAndDevelopmentArrangementContractToPerformForOthersByTypeAxis" xlink:label="loc_us-gaap_ResearchAndDevelopmentArrangementContractToPerformForOthersByTypeAxis_1DB9BE72F879006332B44FCDA09A59AD" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_SubsequentEventTable_A71085BF68C8BE91512E4F97B80C54A4" xlink:to="loc_us-gaap_ResearchAndDevelopmentArrangementContractToPerformForOthersByTypeAxis_1DB9BE72F879006332B44FCDA09A59AD" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ResearchAndDevelopmentArrangementContractToPerformForOthersTypeDomain" xlink:label="loc_us-gaap_ResearchAndDevelopmentArrangementContractToPerformForOthersTypeDomain_699C71D935475036B32D4FCDA09B6D7B_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_ResearchAndDevelopmentArrangementContractToPerformForOthersByTypeAxis_1DB9BE72F879006332B44FCDA09A59AD" xlink:to="loc_us-gaap_ResearchAndDevelopmentArrangementContractToPerformForOthersTypeDomain_699C71D935475036B32D4FCDA09B6D7B_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ResearchAndDevelopmentArrangementContractToPerformForOthersTypeDomain" xlink:label="loc_us-gaap_ResearchAndDevelopmentArrangementContractToPerformForOthersTypeDomain_699C71D935475036B32D4FCDA09B6D7B" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_ResearchAndDevelopmentArrangementContractToPerformForOthersByTypeAxis_1DB9BE72F879006332B44FCDA09A59AD" xlink:to="loc_us-gaap_ResearchAndDevelopmentArrangementContractToPerformForOthersTypeDomain_699C71D935475036B32D4FCDA09B6D7B" xlink:type="arc" />
    <link:loc xlink:href="opht-20190331.xsd#opht_BEST1LicenseAgreementMember" xlink:label="loc_opht_BEST1LicenseAgreementMember_07EEC5EB16353D4709A54FD26F3BA46A" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ResearchAndDevelopmentArrangementContractToPerformForOthersTypeDomain_699C71D935475036B32D4FCDA09B6D7B" xlink:to="loc_opht_BEST1LicenseAgreementMember_07EEC5EB16353D4709A54FD26F3BA46A" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2018/elts/srt-2018-01-31.xsd#srt_CounterpartyNameAxis" xlink:label="loc_srt_CounterpartyNameAxis_D718722292F6CA028E494FCD460F4461" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_SubsequentEventTable_A71085BF68C8BE91512E4F97B80C54A4" xlink:to="loc_srt_CounterpartyNameAxis_D718722292F6CA028E494FCD460F4461" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2018/elts/srt-2018-01-31.xsd#srt_RepurchaseAgreementCounterpartyNameDomain" xlink:label="loc_srt_RepurchaseAgreementCounterpartyNameDomain_F6D8F297873123CF4B954FCD46105A58_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_CounterpartyNameAxis_D718722292F6CA028E494FCD460F4461" xlink:to="loc_srt_RepurchaseAgreementCounterpartyNameDomain_F6D8F297873123CF4B954FCD46105A58_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2018/elts/srt-2018-01-31.xsd#srt_RepurchaseAgreementCounterpartyNameDomain" xlink:label="loc_srt_RepurchaseAgreementCounterpartyNameDomain_F6D8F297873123CF4B954FCD46105A58" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_CounterpartyNameAxis_D718722292F6CA028E494FCD460F4461" xlink:to="loc_srt_RepurchaseAgreementCounterpartyNameDomain_F6D8F297873123CF4B954FCD46105A58" xlink:type="arc" />
    <link:loc xlink:href="opht-20190331.xsd#opht_UniversityOfFloridaResearchFoundationUFRFAndUniversityOfPennsylvaniaPennMember" xlink:label="loc_opht_UniversityOfFloridaResearchFoundationUFRFAndUniversityOfPennsylvaniaPennMember_5AE8CF0678F8431EBB9E4FD05BB61611" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RepurchaseAgreementCounterpartyNameDomain_F6D8F297873123CF4B954FCD46105A58" xlink:to="loc_opht_UniversityOfFloridaResearchFoundationUFRFAndUniversityOfPennsylvaniaPennMember_5AE8CF0678F8431EBB9E4FD05BB61611" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_IncomeStatementLocationAxis" xlink:label="loc_us-gaap_IncomeStatementLocationAxis_DA6B0F34F8D84D9C90BC4FCD0462DA2D" xlink:type="locator" />
    <link:definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_SubsequentEventTable_A71085BF68C8BE91512E4F97B80C54A4" xlink:to="loc_us-gaap_IncomeStatementLocationAxis_DA6B0F34F8D84D9C90BC4FCD0462DA2D" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_IncomeStatementLocationDomain" xlink:label="loc_us-gaap_IncomeStatementLocationDomain_BE7BA3149210705979FE4FCD0466E3BB_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_IncomeStatementLocationAxis_DA6B0F34F8D84D9C90BC4FCD0462DA2D" xlink:to="loc_us-gaap_IncomeStatementLocationDomain_BE7BA3149210705979FE4FCD0466E3BB_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_IncomeStatementLocationDomain" xlink:label="loc_us-gaap_IncomeStatementLocationDomain_BE7BA3149210705979FE4FCD0466E3BB" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_IncomeStatementLocationAxis_DA6B0F34F8D84D9C90BC4FCD0462DA2D" xlink:to="loc_us-gaap_IncomeStatementLocationDomain_BE7BA3149210705979FE4FCD0466E3BB" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ResearchAndDevelopmentExpenseMember" xlink:label="loc_us-gaap_ResearchAndDevelopmentExpenseMember_587F22B723B240F3F92C4FCDDB1347C7" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementLocationDomain_BE7BA3149210705979FE4FCD0466E3BB" xlink:to="loc_us-gaap_ResearchAndDevelopmentExpenseMember_587F22B723B240F3F92C4FCDDB1347C7" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_GeneralAndAdministrativeExpenseMember" xlink:label="loc_us-gaap_GeneralAndAdministrativeExpenseMember_F7F26A5B8737E62FE50C4FD61C418547" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementLocationDomain_BE7BA3149210705979FE4FCD0466E3BB" xlink:to="loc_us-gaap_GeneralAndAdministrativeExpenseMember_F7F26A5B8737E62FE50C4FD61C418547" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_SubsequentEventTypeAxis" xlink:label="loc_us-gaap_SubsequentEventTypeAxis_618A288CC60806C72A674F97B80ED758" xlink:type="locator" />
    <link:definitionArc order="6" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_SubsequentEventTable_A71085BF68C8BE91512E4F97B80C54A4" xlink:to="loc_us-gaap_SubsequentEventTypeAxis_618A288CC60806C72A674F97B80ED758" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_SubsequentEventTypeDomain" xlink:label="loc_us-gaap_SubsequentEventTypeDomain_81D5B3F908E032AC60DD4F97B80E7DFA_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_SubsequentEventTypeAxis_618A288CC60806C72A674F97B80ED758" xlink:to="loc_us-gaap_SubsequentEventTypeDomain_81D5B3F908E032AC60DD4F97B80E7DFA_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_SubsequentEventTypeDomain" xlink:label="loc_us-gaap_SubsequentEventTypeDomain_81D5B3F908E032AC60DD4F97B80E7DFA" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_SubsequentEventTypeAxis_618A288CC60806C72A674F97B80ED758" xlink:to="loc_us-gaap_SubsequentEventTypeDomain_81D5B3F908E032AC60DD4F97B80E7DFA" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_SubsequentEventMember" xlink:label="loc_us-gaap_SubsequentEventMember_BB96BB6F071B9D0AD16B4F97B80FA153" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SubsequentEventTypeDomain_81D5B3F908E032AC60DD4F97B80E7DFA" xlink:to="loc_us-gaap_SubsequentEventMember_BB96BB6F071B9D0AD16B4F97B80FA153" xlink:type="arc" />
    <link:loc xlink:href="opht-20190331.xsd#opht_PaymentsforLicenseFees" xlink:label="loc_opht_PaymentsforLicenseFees_27C8B3EDC1EB863E4A5C4FC2E0977D2D" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SubsequentEventLineItems_F7C60F2F4AF2AC106C154F97B80F0143" xlink:to="loc_opht_PaymentsforLicenseFees_27C8B3EDC1EB863E4A5C4FC2E0977D2D" xlink:type="arc" />
    <link:loc xlink:href="opht-20190331.xsd#opht_NumberofLicensedProducts" xlink:label="loc_opht_NumberofLicensedProducts_75C2C5A3CC3A365B7EB24FBACFBFC78A" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SubsequentEventLineItems_F7C60F2F4AF2AC106C154F97B80F0143" xlink:to="loc_opht_NumberofLicensedProducts_75C2C5A3CC3A365B7EB24FBACFBFC78A" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://www.ophthotech.com/role/SummaryOfSignificantAccountingPolicies" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.ophthotech.com/role/SummaryOfSignificantAccountingPoliciesCashAndCashEquivalentsDetails" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.ophthotech.com/role/SummaryOfSignificantAccountingPoliciesPolicies" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.ophthotech.com/role/SummaryOfSignificantAccountingPoliciesPropertyAndEquipmentDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_PropertyPlantAndEquipmentLineItems" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentLineItems_EC627F96523850E8AEBDC50BE290878C" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ScheduleOfPropertyPlantAndEquipmentTable" xlink:label="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_40E5EE590D73533EAFDAA126AA7300D7" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_EC627F96523850E8AEBDC50BE290878C" xlink:to="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_40E5EE590D73533EAFDAA126AA7300D7" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2018/elts/srt-2018-01-31.xsd#srt_RangeAxis" xlink:label="loc_srt_RangeAxis_DF01DFD16177571DAF1C0CAAFC26C74E" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_40E5EE590D73533EAFDAA126AA7300D7" xlink:to="loc_srt_RangeAxis_DF01DFD16177571DAF1C0CAAFC26C74E" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2018/elts/srt-2018-01-31.xsd#srt_RangeMember" xlink:label="loc_srt_RangeMember_E0F4C98BB31CE6741CE7D8B1E3345C57_1893C69DB7A75D7F96ABC7520819B9EB" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_RangeAxis_DF01DFD16177571DAF1C0CAAFC26C74E" xlink:to="loc_srt_RangeMember_E0F4C98BB31CE6741CE7D8B1E3345C57_1893C69DB7A75D7F96ABC7520819B9EB" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2018/elts/srt-2018-01-31.xsd#srt_RangeMember" xlink:label="loc_srt_RangeMember_F74169AE5BCC5C109EC4D179BA9C996B" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_RangeAxis_DF01DFD16177571DAF1C0CAAFC26C74E" xlink:to="loc_srt_RangeMember_F74169AE5BCC5C109EC4D179BA9C996B" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2018/elts/srt-2018-01-31.xsd#srt_MinimumMember" xlink:label="loc_srt_MinimumMember_5F80B817AA285F489F5C821207231675" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_F74169AE5BCC5C109EC4D179BA9C996B" xlink:to="loc_srt_MinimumMember_5F80B817AA285F489F5C821207231675" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2018/elts/srt-2018-01-31.xsd#srt_MaximumMember" xlink:label="loc_srt_MaximumMember_70B214E00F6D583AA4C4B2D6770F3C7D" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_F74169AE5BCC5C109EC4D179BA9C996B" xlink:to="loc_srt_MaximumMember_70B214E00F6D583AA4C4B2D6770F3C7D" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_PropertyPlantAndEquipmentUsefulLife" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentUsefulLife_3F5D9CCF5CBF5A2C93540F6FEB5C4160" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_EC627F96523850E8AEBDC50BE290878C" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentUsefulLife_3F5D9CCF5CBF5A2C93540F6FEB5C4160" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://www.ophthotech.com/role/SummaryOfSignificantAccountingPoliciesRecentlyAdoptedAccountingPronouncementsDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_NewAccountingPronouncementsOrChangeInAccountingPrincipleLineItems" xlink:label="loc_us-gaap_NewAccountingPronouncementsOrChangeInAccountingPrincipleLineItems_824CC10B171AA007CCF18FF8AA28EBC6" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_NewAccountingPronouncementsOrChangeInAccountingPrincipleTable" xlink:label="loc_us-gaap_NewAccountingPronouncementsOrChangeInAccountingPrincipleTable_45118675B8DB36114D128FF8AA26EB65" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_NewAccountingPronouncementsOrChangeInAccountingPrincipleLineItems_824CC10B171AA007CCF18FF8AA28EBC6" xlink:to="loc_us-gaap_NewAccountingPronouncementsOrChangeInAccountingPrincipleTable_45118675B8DB36114D128FF8AA26EB65" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_AdjustmentsForNewAccountingPronouncementsAxis" xlink:label="loc_us-gaap_AdjustmentsForNewAccountingPronouncementsAxis_2D78A6E6B8B5E7514B3E8FF8AA265385" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_NewAccountingPronouncementsOrChangeInAccountingPrincipleTable_45118675B8DB36114D128FF8AA26EB65" xlink:to="loc_us-gaap_AdjustmentsForNewAccountingPronouncementsAxis_2D78A6E6B8B5E7514B3E8FF8AA265385" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_TypeOfAdoptionMember" xlink:label="loc_us-gaap_TypeOfAdoptionMember_224086645AA75074CA998FF8AA267847_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AdjustmentsForNewAccountingPronouncementsAxis_2D78A6E6B8B5E7514B3E8FF8AA265385" xlink:to="loc_us-gaap_TypeOfAdoptionMember_224086645AA75074CA998FF8AA267847_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_TypeOfAdoptionMember" xlink:label="loc_us-gaap_TypeOfAdoptionMember_224086645AA75074CA998FF8AA267847" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AdjustmentsForNewAccountingPronouncementsAxis_2D78A6E6B8B5E7514B3E8FF8AA265385" xlink:to="loc_us-gaap_TypeOfAdoptionMember_224086645AA75074CA998FF8AA267847" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_AccountingStandardsUpdate201602Member" xlink:label="loc_us-gaap_AccountingStandardsUpdate201602Member_26D400B3DEFD3ADD30498FF8AA26A350" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TypeOfAdoptionMember_224086645AA75074CA998FF8AA267847" xlink:to="loc_us-gaap_AccountingStandardsUpdate201602Member_26D400B3DEFD3ADD30498FF8AA26A350" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_StatementEquityComponentsAxis" xlink:label="loc_us-gaap_StatementEquityComponentsAxis_D0A48C10E0B87393CF1B8FF8AA271189" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_NewAccountingPronouncementsOrChangeInAccountingPrincipleTable_45118675B8DB36114D128FF8AA26EB65" xlink:to="loc_us-gaap_StatementEquityComponentsAxis_D0A48C10E0B87393CF1B8FF8AA271189" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_EquityComponentDomain" xlink:label="loc_us-gaap_EquityComponentDomain_1CD35226D6E4A81FC1758FF8AA27F0F4_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_D0A48C10E0B87393CF1B8FF8AA271189" xlink:to="loc_us-gaap_EquityComponentDomain_1CD35226D6E4A81FC1758FF8AA27F0F4_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_EquityComponentDomain" xlink:label="loc_us-gaap_EquityComponentDomain_1CD35226D6E4A81FC1758FF8AA27F0F4" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_D0A48C10E0B87393CF1B8FF8AA271189" xlink:to="loc_us-gaap_EquityComponentDomain_1CD35226D6E4A81FC1758FF8AA27F0F4" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_AdditionalPaidInCapitalMember" xlink:label="loc_us-gaap_AdditionalPaidInCapitalMember_557651DE9E0F87DA2ECF8FF8AA27CAE0" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_1CD35226D6E4A81FC1758FF8AA27F0F4" xlink:to="loc_us-gaap_AdditionalPaidInCapitalMember_557651DE9E0F87DA2ECF8FF8AA27CAE0" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_OperatingLeaseRightOfUseAsset" xlink:label="loc_us-gaap_OperatingLeaseRightOfUseAsset_BFEEA9168A43AE6704C38FF8AA284963" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NewAccountingPronouncementsOrChangeInAccountingPrincipleLineItems_824CC10B171AA007CCF18FF8AA28EBC6" xlink:to="loc_us-gaap_OperatingLeaseRightOfUseAsset_BFEEA9168A43AE6704C38FF8AA284963" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_OperatingLeaseLiability" xlink:label="loc_us-gaap_OperatingLeaseLiability_399920F093FA39E0CB928FF8AA28F729" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NewAccountingPronouncementsOrChangeInAccountingPrincipleLineItems_824CC10B171AA007CCF18FF8AA28EBC6" xlink:to="loc_us-gaap_OperatingLeaseLiability_399920F093FA39E0CB928FF8AA28F729" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_OperatingLeaseWeightedAverageDiscountRatePercent" xlink:label="loc_us-gaap_OperatingLeaseWeightedAverageDiscountRatePercent_A4C92035202DB2AFD2758FF8AA28DB7E" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NewAccountingPronouncementsOrChangeInAccountingPrincipleLineItems_824CC10B171AA007CCF18FF8AA28EBC6" xlink:to="loc_us-gaap_OperatingLeaseWeightedAverageDiscountRatePercent_A4C92035202DB2AFD2758FF8AA28DB7E" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://www.ophthotech.com/role/SummaryOfSignificantAccountingPoliciesScheduleOfWeightedAverageAssumptionsDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_5285EB4C14055AEE91D6928331F3B0AD" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable" xlink:label="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_0B028D0D69EE5CF68B1D4D94F4D8827D" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_5285EB4C14055AEE91D6928331F3B0AD" xlink:to="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_0B028D0D69EE5CF68B1D4D94F4D8827D" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_AwardTypeAxis" xlink:label="loc_us-gaap_AwardTypeAxis_DC7982C4A72C5AB7955A82226081AFA5" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_0B028D0D69EE5CF68B1D4D94F4D8827D" xlink:to="loc_us-gaap_AwardTypeAxis_DC7982C4A72C5AB7955A82226081AFA5" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_2A9C9C3CE1C76A3413C5F215E050CF56_1893C69DB7A75D7F96ABC7520819B9EB" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AwardTypeAxis_DC7982C4A72C5AB7955A82226081AFA5" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_2A9C9C3CE1C76A3413C5F215E050CF56_1893C69DB7A75D7F96ABC7520819B9EB" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_25950EE0C68F508AB6E7A38D1F0EEA9E" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AwardTypeAxis_DC7982C4A72C5AB7955A82226081AFA5" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_25950EE0C68F508AB6E7A38D1F0EEA9E" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_EmployeeStockOptionMember" xlink:label="loc_us-gaap_EmployeeStockOptionMember_384E33323972567789B3A8ABE5E896B2" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_25950EE0C68F508AB6E7A38D1F0EEA9E" xlink:to="loc_us-gaap_EmployeeStockOptionMember_384E33323972567789B3A8ABE5E896B2" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRate" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRate_0FEC32C5DC2E581DBA82FA5AD3736787" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_5285EB4C14055AEE91D6928331F3B0AD" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRate_0FEC32C5DC2E581DBA82FA5AD3736787" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRateMinimum" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRateMinimum_6AA4169347235E0681A81B9834A9F8BF" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_5285EB4C14055AEE91D6928331F3B0AD" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRateMinimum_6AA4169347235E0681A81B9834A9F8BF" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRateMaximum" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRateMaximum_8BFD267DC1F6589D966ED0D6902561A9" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_5285EB4C14055AEE91D6928331F3B0AD" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRateMaximum_8BFD267DC1F6589D966ED0D6902561A9" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardFairValueAssumptionsExpectedTerm1" xlink:label="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardFairValueAssumptionsExpectedTerm1_7E6BEC34EF1D5574A708069265ED2726" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_5285EB4C14055AEE91D6928331F3B0AD" xlink:to="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardFairValueAssumptionsExpectedTerm1_7E6BEC34EF1D5574A708069265ED2726" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedDividendRate" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedDividendRate_9F08631B1863520885D98BB1A2409636" xlink:type="locator" />
    <link:definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_5285EB4C14055AEE91D6928331F3B0AD" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedDividendRate_9F08631B1863520885D98BB1A2409636" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://www.ophthotech.com/role/SummaryOfSignificantAccountingPoliciesSegmentAndGeographicInformationDetails" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.ophthotech.com/role/SummaryOfSignificantAccountingPoliciesShareBasedCompensationDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_EmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsLineItems" xlink:label="loc_us-gaap_EmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsLineItems_7FE2A42970ABEE9AF6FA4FC2FF1C85CF" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ScheduleOfEmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsTable" xlink:label="loc_us-gaap_ScheduleOfEmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsTable_CDCB8BD89AA4A4CED5084FC2FF1843D3" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_EmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsLineItems_7FE2A42970ABEE9AF6FA4FC2FF1C85CF" xlink:to="loc_us-gaap_ScheduleOfEmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsTable_CDCB8BD89AA4A4CED5084FC2FF1843D3" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_AwardTypeAxis" xlink:label="loc_us-gaap_AwardTypeAxis_8A085EF3FC383C51EA564FC2FF19D910" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfEmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsTable_CDCB8BD89AA4A4CED5084FC2FF1843D3" xlink:to="loc_us-gaap_AwardTypeAxis_8A085EF3FC383C51EA564FC2FF19D910" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_D1E9DC3169F3362C14604FC2FF195F13_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AwardTypeAxis_8A085EF3FC383C51EA564FC2FF19D910" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_D1E9DC3169F3362C14604FC2FF195F13_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_D1E9DC3169F3362C14604FC2FF195F13" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AwardTypeAxis_8A085EF3FC383C51EA564FC2FF19D910" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_D1E9DC3169F3362C14604FC2FF195F13" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_EmployeeStockMember" xlink:label="loc_us-gaap_EmployeeStockMember_2B130EEAFDB51ACF57874FC2FF195CBD" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_D1E9DC3169F3362C14604FC2FF195F13" xlink:to="loc_us-gaap_EmployeeStockMember_2B130EEAFDB51ACF57874FC2FF195CBD" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2018/elts/srt-2018-01-31.xsd#srt_RangeAxis" xlink:label="loc_srt_RangeAxis_5B5E52BA4AD6837253A64FC2FF1A0151" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfEmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsTable_CDCB8BD89AA4A4CED5084FC2FF1843D3" xlink:to="loc_srt_RangeAxis_5B5E52BA4AD6837253A64FC2FF1A0151" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2018/elts/srt-2018-01-31.xsd#srt_RangeMember" xlink:label="loc_srt_RangeMember_A14DF84E2DB01711D8604FC2FF1AB4BF_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_RangeAxis_5B5E52BA4AD6837253A64FC2FF1A0151" xlink:to="loc_srt_RangeMember_A14DF84E2DB01711D8604FC2FF1AB4BF_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2018/elts/srt-2018-01-31.xsd#srt_RangeMember" xlink:label="loc_srt_RangeMember_A14DF84E2DB01711D8604FC2FF1AB4BF" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_RangeAxis_5B5E52BA4AD6837253A64FC2FF1A0151" xlink:to="loc_srt_RangeMember_A14DF84E2DB01711D8604FC2FF1AB4BF" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2018/elts/srt-2018-01-31.xsd#srt_MaximumMember" xlink:label="loc_srt_MaximumMember_1155CB4E86047B7B9CFC4FC2FF1A5FE4" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_A14DF84E2DB01711D8604FC2FF1AB4BF" xlink:to="loc_srt_MaximumMember_1155CB4E86047B7B9CFC4FC2FF1A5FE4" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_IncomeStatementLocationAxis" xlink:label="loc_us-gaap_IncomeStatementLocationAxis_5FA82F0829CA15B2E4524FC2FF1B2178" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfEmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsTable_CDCB8BD89AA4A4CED5084FC2FF1843D3" xlink:to="loc_us-gaap_IncomeStatementLocationAxis_5FA82F0829CA15B2E4524FC2FF1B2178" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_IncomeStatementLocationDomain" xlink:label="loc_us-gaap_IncomeStatementLocationDomain_1B5BF2F1030FC0612CEE4FC2FF1B8849_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_IncomeStatementLocationAxis_5FA82F0829CA15B2E4524FC2FF1B2178" xlink:to="loc_us-gaap_IncomeStatementLocationDomain_1B5BF2F1030FC0612CEE4FC2FF1B8849_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_IncomeStatementLocationDomain" xlink:label="loc_us-gaap_IncomeStatementLocationDomain_1B5BF2F1030FC0612CEE4FC2FF1B8849" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_IncomeStatementLocationAxis_5FA82F0829CA15B2E4524FC2FF1B2178" xlink:to="loc_us-gaap_IncomeStatementLocationDomain_1B5BF2F1030FC0612CEE4FC2FF1B8849" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ResearchAndDevelopmentExpenseMember" xlink:label="loc_us-gaap_ResearchAndDevelopmentExpenseMember_5AD177CB3B6ACC4144204FC2FF1BCD46" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementLocationDomain_1B5BF2F1030FC0612CEE4FC2FF1B8849" xlink:to="loc_us-gaap_ResearchAndDevelopmentExpenseMember_5AD177CB3B6ACC4144204FC2FF1BCD46" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_GeneralAndAdministrativeExpenseMember" xlink:label="loc_us-gaap_GeneralAndAdministrativeExpenseMember_1CCA8A1F9A4EDD750B8D4FC2FF1C2E8C" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementLocationDomain_1B5BF2F1030FC0612CEE4FC2FF1B8849" xlink:to="loc_us-gaap_GeneralAndAdministrativeExpenseMember_1CCA8A1F9A4EDD750B8D4FC2FF1C2E8C" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedDividendRate" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedDividendRate_E2D15EBCF43C8C133F324FC2FF1CB981" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsLineItems_7FE2A42970ABEE9AF6FA4FC2FF1C85CF" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedDividendRate_E2D15EBCF43C8C133F324FC2FF1CB981" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAuthorized" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAuthorized_58479906E814F5AAC2864FC2FF1D5772" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsLineItems_7FE2A42970ABEE9AF6FA4FC2FF1C85CF" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAuthorized_58479906E814F5AAC2864FC2FF1D5772" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://www.ophthotech.com/role/SummaryOfSignificantAccountingPoliciesTables" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.ophthotech.com/role/UnauditedConsolidatedBalanceSheets" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.ophthotech.com/role/UnauditedConsolidatedBalanceSheetsParenthetical" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.ophthotech.com/role/UnauditedConsolidatedStatementsOfCashFlows" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.ophthotech.com/role/UnauditedConsolidatedStatementsOfOperationsAndComprehensiveLoss" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.ophthotech.com/role/UnauditedConsolidatedStatementsOfStockholdersEquity" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_StatementLineItems" xlink:label="loc_us-gaap_StatementLineItems_944DD64852CD140681C4987E6257EF43" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_StatementTable" xlink:label="loc_us-gaap_StatementTable_F66819E4202F85680980987E6252DECC" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_StatementLineItems_944DD64852CD140681C4987E6257EF43" xlink:to="loc_us-gaap_StatementTable_F66819E4202F85680980987E6252DECC" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_StatementEquityComponentsAxis" xlink:label="loc_us-gaap_StatementEquityComponentsAxis_1BFA5DA9116B8ACD2909987E6253EC99" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_StatementTable_F66819E4202F85680980987E6252DECC" xlink:to="loc_us-gaap_StatementEquityComponentsAxis_1BFA5DA9116B8ACD2909987E6253EC99" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_EquityComponentDomain" xlink:label="loc_us-gaap_EquityComponentDomain_F3F5CD2DD3ACB9E73819987E62539EBD_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_1BFA5DA9116B8ACD2909987E6253EC99" xlink:to="loc_us-gaap_EquityComponentDomain_F3F5CD2DD3ACB9E73819987E62539EBD_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_EquityComponentDomain" xlink:label="loc_us-gaap_EquityComponentDomain_F3F5CD2DD3ACB9E73819987E62539EBD" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_1BFA5DA9116B8ACD2909987E6253EC99" xlink:to="loc_us-gaap_EquityComponentDomain_F3F5CD2DD3ACB9E73819987E62539EBD" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_PreferredStockMember" xlink:label="loc_us-gaap_PreferredStockMember_297F50C2FF2D0CF2047D987E62547AAE" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_F3F5CD2DD3ACB9E73819987E62539EBD" xlink:to="loc_us-gaap_PreferredStockMember_297F50C2FF2D0CF2047D987E62547AAE" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_CommonStockMember" xlink:label="loc_us-gaap_CommonStockMember_1EC0EEC176B770572AF9987E6256E673" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_F3F5CD2DD3ACB9E73819987E62539EBD" xlink:to="loc_us-gaap_CommonStockMember_1EC0EEC176B770572AF9987E6256E673" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_AdditionalPaidInCapitalMember" xlink:label="loc_us-gaap_AdditionalPaidInCapitalMember_7625AD0E4BB60BC47B91987E6256A8AB" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_F3F5CD2DD3ACB9E73819987E62539EBD" xlink:to="loc_us-gaap_AdditionalPaidInCapitalMember_7625AD0E4BB60BC47B91987E6256A8AB" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_RetainedEarningsMember" xlink:label="loc_us-gaap_RetainedEarningsMember_168F4DEF0B7B49DF8349987E6257558D" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_F3F5CD2DD3ACB9E73819987E62539EBD" xlink:to="loc_us-gaap_RetainedEarningsMember_168F4DEF0B7B49DF8349987E6257558D" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_IncreaseDecreaseInStockholdersEquityRollForward" xlink:label="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_350B9EA9B1FB0370463D987E6257A7C8" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_944DD64852CD140681C4987E6257EF43" xlink:to="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_350B9EA9B1FB0370463D987E6257A7C8" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_SharesIssued" xlink:label="loc_us-gaap_SharesIssued_404CC998BFFE2D6B52E6987E6257E320" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_350B9EA9B1FB0370463D987E6257A7C8" xlink:to="loc_us-gaap_SharesIssued_404CC998BFFE2D6B52E6987E6257E320" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_StockholdersEquity" xlink:label="loc_us-gaap_StockholdersEquity_B897B89A1087A78699CF987E6258EA27" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_350B9EA9B1FB0370463D987E6257A7C8" xlink:to="loc_us-gaap_StockholdersEquity_B897B89A1087A78699CF987E6258EA27" xlink:type="arc" />
    <link:loc xlink:href="opht-20190331.xsd#opht_StockIssuedDuringPeriodSharesOptionsAndWarrantsExercised" xlink:label="loc_opht_StockIssuedDuringPeriodSharesOptionsAndWarrantsExercised_49B0B1321CE9C8EA8893987E62584C87" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_350B9EA9B1FB0370463D987E6257A7C8" xlink:to="loc_opht_StockIssuedDuringPeriodSharesOptionsAndWarrantsExercised_49B0B1321CE9C8EA8893987E62584C87" xlink:type="arc" />
    <link:loc xlink:href="opht-20190331.xsd#opht_StockIssuedDuringPeriodValueStockOptionsAndWarrantsExercised" xlink:label="loc_opht_StockIssuedDuringPeriodValueStockOptionsAndWarrantsExercised_B256884F89F165F786EA987E6258405E" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_350B9EA9B1FB0370463D987E6257A7C8" xlink:to="loc_opht_StockIssuedDuringPeriodValueStockOptionsAndWarrantsExercised_B256884F89F165F786EA987E6258405E" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue" xlink:label="loc_us-gaap_AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue_C4BA379575E41A1858F8987E62595247" xlink:type="locator" />
    <link:definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_350B9EA9B1FB0370463D987E6257A7C8" xlink:to="loc_us-gaap_AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue_C4BA379575E41A1858F8987E62595247" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_NetIncomeLoss" xlink:label="loc_us-gaap_NetIncomeLoss_9C9F07A911A3ADD2280D987E6259843D" xlink:type="locator" />
    <link:definitionArc order="6" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_350B9EA9B1FB0370463D987E6257A7C8" xlink:to="loc_us-gaap_NetIncomeLoss_9C9F07A911A3ADD2280D987E6259843D" xlink:type="arc" />
  </link:definitionLink>
</link:linkbase>
