Visual Acuity in Retinal Vein Occlusion, Diabetic, and Uveitic Macular Edema: Central Subfield Thickness and Ellipsoid Zone Analysis

Abstract

Purpose: This study assessed relationships between best-corrected visual acuity (BCVA), central subfield thickness (CST), and ellipsoid zone (EZ) integrity in macular edema (ME) patients.

Design: Post hoc analysis of 6 clinical trials, which included verified diagnoses, protocol refractions, and reading center assessment of OCT images.

Participants: Participants (n = 1063) were diagnosed with ME from retinal vein occlusion (RVO), diabetic retinopathy (DR; diabetic macular edema, DME), or noninfectious uveitis (NIU).

Methods: For CST, 2 clinical trials for each disorder were analyzed. For EZ, 3 studies across 2 disorders were analyzed.

Main outcome measures: Primary outcomes were correlations between BCVA and CST, and between BCVA and 4 central subfield EZ grades.

Results: For baseline BCVA and CST, Pearson correlation coefficients were: ME from RVO, -0.56 (774 eyes; 95% confidence interval [CI], -0.61 to -0.51; P < 0.001); DME, -0.50 (91 eyes; 95% CI, -0.64 to -0.33; P < 0.001); and ME from NIU, -0.38 (198 eyes; 95% CI, -0.49 to -0.26; P < 0.001). Regarding change from baseline to 24 weeks for both BCVA and CST, Pearson correlation coefficients were: ME from RVO, -0.35 (95% CI, -0.43 to -0.27; P < 0.001); DME, -0.30 (95% CI, -0.48 to -0.09; P = 0.006); and ME from NIU, -0.42 (95% CI, -0.53 to -0.29; P < 0.001). Acute and chronic ME showed similar baseline and 24-week change linear correlations. With lower baseline CST, a trend of decreased baseline and 24-week change correlations was found. For central subfield EZ at baseline, mean BCVA progressively worsened with each of 4 EZ grades in 185 eyes with gradable EZ (DME, 41 eyes; NIU, 144 eyes; P ≤ 0.050 for all pairwise comparisons except between normal and questionably abnormal EZ grades). Eyes with normal baseline central subfield EZ showed greater 24-week change in BCVA than those with abnormal baseline EZ (15.00 letters vs. 8.16 letters; P = 0.0005, with baseline BCVA, CST, and age as covariates).

Conclusions: Despite these correlations, CST and EZ integrity, as graded herein, account for the minority of BCVA variation in patients with ME resulting from RVO, DR, and NIU.

Keywords: Central subfield thickness; Ellipsoid zone; Macular edema; Photoreceptor inner segment–outer segment junction; Visual acuity.