A Study to Learn About the Blood Levels of Aflibercept When High-dose Aflibercept is Injected in Both Eyes of Participants With Diabetic Macular Edema or Neovascular Age-related Macular Degeneration

Inclusion Criteria: * Men or women ≥18 years of age (or country's legal age of adulthood if the legal age is \>18 years). * Participants (treatment naïve or previously treated) requiring intravitreal anti-vascular endothelial growth factor (VEGF) treatment in both eyes in the opinion of the investigator. * Participants with type 1 or type 2 diabetes mellitus and DME in both eyes with active central involvement (CI-DME) in at least one eye with central retinal thickness (CRT) ≥300 µm (or ≥320 µm on Spectralis) as determined by the investigator at the screening visit, OR diagnosis of nAMD in both eyes with active subfoveal choroidal neovascularization (CNV) in at least one eye with intraretinal fluid (IRF) and/or subretinal fluid (SRF) on OCT as determined by the investigator at the screening visit. * Best corrected visual acuity (BCVA) Early Treatment Diabetic Retinopathy Study (ETDRS) letter score of 78 to 24 (approximate Snellen equivalent of 20/32 to 20/320) in eyes with active disease and decreased vision determined to be primarily the result of DME or nAMD. * A female participant is eligible to participate if she is not pregnant or breastfeeding. Women of childbearing potential (WOCBP) or men who are sexually active with partners of childbearing potential must agree to use highly effective contraception prior to the initial dose/start of the first treatment, during the study, and for at least 4 months after the last administration of study intervention. Exclusion Criteria: * Evidence of macular edema due to any cause other than diabetes mellitus in patients with DME or neovascular age-related macular degeneration in patients with nAMD in either eye. * Active proliferative diabetic retinopathy (DR) in either eye. * Panretinal laser photocoagulation (PRP) or macular laser photocoagulation in either eye with CI-DME or active nAMD within 12 weeks (84 days) of the screening visit. * Prior treatment with intravitreal (IVT) 2 mg aflibercept (EYLEA) in either eye within 12 weeks (84 days) of the screening visit or with IVT 8 mg or HD aflibercept in either eye within 24 weeks (168 days) of the screening visit. * Prior treatment with any other approved IVT agent with anti-VEGF effect (e.g. ranibizumab, bevacizumab, brolucizumab, faricimab, pegaptanib sodium or biosimilars) in either eye within 4 weeks (28 days) of the screening visit. * Prior treatment with any ocular gene or cell therapy treatment in either eye. * Previous use of intraocular or periocular corticosteroids in either eye within 16 weeks (112 days) of the screening visit, or OZURDEX® implant within 180 days of the screening visit or ILUVIEN® or RETISERT® implant at any time