A Clinical Trial of MK-8748 Compared to Aflibercept in Participants With Diabetic Macular Edema (MK-8748-004)

Researchers are looking for new ways to treat diabetic macular edema (DME). In this trial, researchers want to learn if a trial medicine called MK-8748 can treat DME. An available standard (usual) treatment for DME is aflibercept. However, standard treatments such as aflibercept may not work for every person. The main goal of this trial is to learn if MK-8748 works as well as aflibercept to treat DME.

Inclusion Criteria: The main inclusion criteria include but are not limited to the following: * Has Type 1 or Type 2 diabetes mellitus and a hemoglobin A1c (HbA1c) of ≤12% * Has a decrease in vision in the study eye determined by the Investigator to be primarily the result of diabetic macular edema (DME) * For participants who are treatment-naïve for DME, the diagnosis must have been made within 9 months of screening. For all treatment-experienced participants, the first treatment should have been no longer than 3 years prior to the Screening visit Exclusion Criteria: The main exclusion criteria include but are not limited to the following: * Has had renal failure requiring renal transplant, hemodialysis, or peritoneal dialysis or has renal failure anticipated to require hemodialysis or peritoneal dialysis at any time during the study * Has history of stroke (cerebral vascular accident) or myocardial infarction within 180 days to first dose of study intervention * Has newly diagnosed or previously untreated diabetes mellitus and initiated oral or injectable anti-diabetic medication within 3 months to first dose of study intervention * Has history of cataract surgery and/or minimally invasive glaucoma surgery in the study eye within 90 days of screening * Has any treatment for complications of cataract surgery with steroids or yttrium aluminum garnet (YAG) laser capsulotomy in the study eye within 90 days of screening * Has advanced or uncontrolled glaucoma in the study eye * Has any history of retinal detachment or treatment or surgery for retinal detachment in the study eye * Has active retinal disease other than the condition under investigation in the study eye * Has uncontrolled blood pressure at screening