Structural and vascular correlates of visual field defects in branch retinal vein occlusion: a multimodal imaging study

BACKGROUND: To evaluate the association between visual field (VF) defects and retinal structural and perfusion biomarkers in eyes with branch retinal vein occlusion (BRVO), using optical coherence tomography (OCT) and OCT angiography (OCTA). METHODS: This retrospective cross-sectional study included 85 patients with unilateral BRVO. The eyes were classified as having either major or macular BRVO. VFs were assessed using the Humphrey 24-2 VF testing. Structural parameters were obtained from spectral-domain OCT for each parafoveal and perifoveal sublayer thickness in the superior and inferior fields. Perfusion parameters from 3×3 mm macular OCTA included vessel density (VD) in the superficial and deep capillary plexuses (DCPs), foveal avascular zone area, central non-perfusion area (NPA) and parafoveal NPA. Eyes were stratified by VF mean deviation (MD): Group 1 (significant VF defect, MD ≤-6 dB) and Group 2 (mild VF defect, MD >-6 dB). Intergroup comparisons, correlations and multivariate regression analyses were performed. RESULTS: Group 1 (n=27) had a significantly higher prevalence of major BRVO (96.3 vs 65.5%) than Group 2 (n=58). Group 1 showed thinner parafoveal ganglion cell-inner plexiform layer (GCIPL) (76.8±14.7 vs. 87.9±11.9 µm; p<0.001) and outer plexiform layer (32.5±6.6 vs. 36.1±5.5 µm; p=0.024). Hemispheric VD in the DCP was lower in Group 1 (28.9±6.2% vs. 32.7±8.1%; p=0.031). In multivariate analysis, BRVO type and parafoveal GCIPL thickness were independent predictors of significant VF loss. CONCLUSIONS: VF impairment in BRVO was strongly associated with inner retinal thinning than with OCTA parameters. VF testing and structural OCT can be complemented by acuity-based assessments of BRVO.