COMPARISON OF SUBFOVEAL CHOROIDAL THICKNESS IN DIABETICS AND VARIOUS GRADES OF DIABETIC RETINOPATHY

Abstract

Background: Diabetic retinopathy (DR) is a major cause of vision loss in adults and, although traditionally viewed as a retinal microvascular disorder, growing evidence indicates that the choroid also plays an important role in its pathophysiology. Alterations in subfoveal choroidal thickness (SFCT) may reflect early structural changes in diabetic eyes, but previous studies have shown inconsistent results, particularly within the Indian population. Objectives: To evaluate SFCT in diabetic individuals and compare its variation across different grades of DR using enhanced-depth imaging optical coherence tomography (EDI-OCT). Methods: This cross-sectional observational study included 180 eyes of diabetic patients aged ≥18 years at a tertiary care center. Participants were classified into diabetes without DR and diabetes with DR, the latter graded according to ETDRS criteria. All subjects underwent detailed ophthalmic examination and EDI-OCT imaging. SFCT was manually measured at the foveal center by a blinded observer. Statistical analysis included the t-test, Kruskal–Wallis test, and Spearman correlation. Results: The DR group had a significantly longer duration of diabetes compared to those without DR (6.63 ± 5.15 vs. 4.44 ± 3.21 years; p = 0.002). Mean SFCT was significantly higher in diabetics without DR (276.90 ± 31.04 µm) than in those with DR (254.20 ± 70.90 µm; p = 0.002). Among 105 eyes with DR, SFCT progressively decreased with increasing severity (p < 0.001), ranging from 327.56 ± 25.05 µm in mild NPDR to 154.62 ± 16.32 µm in severe NPDR. SFCT showed a significant negative correlation with duration of diabetes (r = –0.344; p < 0.001). Conclusion: SFCT decreases significantly with the presence and progression of DR and correlates negatively with diabetes duration. Choroidal thickness measurement may serve as a useful structural biomarker for assessing DR severity and progression risk.