Background Diabetic retinopathy (DR) is a leading cause of vision loss globally. Optical coherence tomography (OCT) provides objective biomarkers that reflect both vascular and neurodegenerative changes in DR. Comparing OCT biomarkers between non-proliferative DR (NPDR) and proliferative DR (PDR) may provide insights into disease progression and visual outcomes. Objectives To compare OCT biomarkers between NPDR and PDR patients and to assess their correlation with visual acuity. Methods This cross-sectional observational study was conducted in the Department of Ophthalmology, GMC Palakkad, from November 2024 to April 2025. A total of 150 diabetic patients (300 eyes, 195NPDR, 105 PDR) underwent comprehensive ophthalmic evaluation and spectral-domain OCT imaging. Demographic data, best corrected visual acuity (BCVA), and OCT biomarkers—including central subfield thickness (CST), intraretinal cysts, subretinal fluid (SRF), disorganization of retinal inner layers (DRIL), ellipsoid zone (EZ) disruption, and hyperreflective foci (HRF)-were recorded and analyzed. Results The mean age of participants was 57.8 ± 8.6 years, with a male-to-female ratio of 1.4:1. The mean BCVA was significantly poorer in PDR eyes compared to NPDR (p < 0.05). CST was higher in PDR eyes (322 ± 48µm) compared to NPDR (285 ± 42 µm). DRIL was observed in 55% of PDR versus 53% of NPDR eyes, while EZ disruption was significantly more frequent in PDR (p < 0.05). HRF and intraretinal cysts were more common in PDR, whereas SRF was seen predominantly in advanced cases. A strong correlation was observed between OCT biomarkers (especially DRIL and EZ disruption) and visual acuity.

Diabetic Retinopathy, OCT Biomarkers, DRIL, Ellipsoid Zone Disruption, Hyperreflective Foci, Central Subfield Thickness.