Structural Fingerprints of Chronic Ischemia: Inner Retinal Atrophy Predicts Severe Visual Field Impairment More Strongly Than Current Macular Perfusion in Branch Retinal Vein Occlusion

초록

Purpose : Functional decline from scotomas is common in Branch Retinal Vein Occlusion (BRVO) even with preserved central acuity. We utilized multimodal imaging—OCT for structure and OCT Angiography (OCTA) for perfusion—to identify retinal biomarkers best correlating with the severity of functional impairment (visual field [VF] loss). Methods : This retrospective, cross-sectional analysis included 85 patients with unilateral BRVO. Functional status was quantified using the Humphrey 24-2 protocol (Mean Deviation [MD]). Patients were divided into Group 1 (significant deterioration; MD ≤ −6 dB; n=27) and Group 2 (mild defects; MD > −6 dB; n=58). We measured sublayer thicknesses, specifically parafoveal Ganglion Cell–Inner Plexiform Layer (GCIPL) and Outer Plexiform Layer (OPL), using SD-OCT. Vessel density (VD) in the superficial (SCP) and deep capillary plexuses (DCP) was measured via 3×3 mm OCTA. Multivariate regression identified independent predictors of severe VF loss. Results : Group 1 had a significantly higher proportion of Major BRVO compared to Group 2 (26/1 vs. 38/20; p=0.002). Structural analysis demonstrated that the Group 1 cohort exhibited substantial inner retinal atrophy, specifically reduced parafoveal GCIPL thickness (76.8 14.7 m vs. 87.9 11.9 m in Group 2; p<0.001). Furthermore, parafoveal OPL thickness was significantly thinner in Group 1 (32.5 6.6 m vs. 36.1 5.5 m; p=0.011). In contrast, macular OCTA findings were less discriminating; only hemispheric DCP-VD in the affected region was statistically lower in Group 1 (28.87 6.20% vs. 32.74 8.14%; p=0.031). Multivariate logistic regression analysis identified BRVO type (major), parafoveal GCIPL thickness, and half OPL thickness as independent predictors of significant VF loss. Conclusions : In chronic BRVO, functional status is more robustly associated with structural thinning of the inner retina—indicating accumulated ischemic neurodegeneration—than with current macular capillary perfusion. GCIPL and OPL thicknesses serve as objective, practical surrogates for functional assessment. Integrating BRVO subtype and structural OCT parameters into clinical evaluation is crucial to complement visual acuity and accurately predict functional impairment.