The goal of this clinical trial is to see if treatment with faricimab or biosimilar ranibizumab leads to different early imaging changes in adults with diabetic retinopathy requiring anti-VEGF treatment and to identify OCT and OCTA biomarkers predictive of differential early treatment response between the two therapies. The main questions it aims to answer are:

Which OCT and OCT angiography biomarkers predict early treatment response? How do imaging biomarkers change after three loading doses of treatment? Are imaging biomarkers associated with systemic laboratory parameters? Researchers will compare faricimab to biosimilar ranibizumab to see if there are differences in imaging biomarkers and early treatment response.

Participants will:

• be randomized in a 1:1 ratio using a computer-generated randomization sequence
• undergo comprehensive ophthalmic examinations, including visual acuity and intraocular pressure measurement
• undergo OCT and OCT angiography imaging at each visit
• receive three intravitreal injections during the loading phase
• attend follow-up visits from baseline to 4-5 weeks after the third injection
• provide blood samples for systemic laboratory analysis

Inclusion Criteria:

• Adults aged ≥18 years
• Diabetic retinopathy with or without central macular edema
• Indication for intravitreal anti-VEGF therapy according to current clinical guidelines
• Ability to provide written informed consent

Exclusion Criteria:

• Intravitreal anti-VEGF or corticosteroid treatment in the study eye within 5 months prior to enrollment
• Any intraocular surgery (including cataract surgery) 3 months prior intraocular surgery to enrollment
• Retinal laser photocoagulation in the study eye within 3 months prior to enrollment
• Presence of other ocular, retinal or macular diseases that may affect OCT/OCTA findings or visual acuity (e.g., age-related macular degeneration, retinal vascular occlusions)
• Retinal detachment, preretinal fibrosis, vitreomacular traction
• Significant media opacities (e.g., dense cataract, vitreous hemorrhage) precluding reliable OCT/OCTA imaging
• Uncontrolled glaucoma (intraocular pressure > 30 mmHg in study eye)
• Active ocular inflammation
• Suspected active ocular infection in either eye
• Any febrile illness within 1 week prior to first injection
• History or presence of any clinically significant disease, non-diabetic metabolic disorder, abnormal physical examination finding, or laboratory abnormality that, in the opinion of the investigator, may contraindicate treatment with faricimab or biosimilar ranibizumab, interfere with the interpretation of study results, or place the participant at increased risk of treatment-related complications.
• Women who are pregnant, breastfeeding, or planning pregnancy within the next 100 weeks
• Known hypersensitivity to faricimab or biosimilar ranibizumab or any of its excipients
• Participation in another clinical trial that may affect study outcomes
• Inability to comply with study procedures or follow-up