Rate and associations of inner retinal thinning in eyes with retinal vein occlusion and regressed macular oedema

Purpose: To investigate the associations between visual acuity (VA) and structural optical coherence tomography (OCT) features in retinal vein occlusion (RVO) eyes after cystoid macular oedema (CMO) regression and to assess whether inner retinal thinning is progressive. Methods: Retrospective observational study of RVO eyes with regressed CMO for at least 6 months. OCT scans at CMO regression were analysed, and features were correlated with VA at that visit. The inner retinal thickness was longitudinally compared between RVO and unaffected fellow eyes (controls) with linear mixed models. The rate of inner retinal thinning was obtained as the interaction term between disease status and time. Associations between inner retinal thinning and clinical characteristics were explored. Results: Thirty-six RVO eyes were followed for 34.2 ± 21.1 months after CMO regression. The presence of ellipsoid zone disruption (regression estimate[standard error(SE)] = 0.16[0.04] LogMAR vs. intact, p < 0.001) and lower inner retinal thickness (regression estimate[SE] = −0.25[0.12] LogMAR for 100-μm increase, p = 0.01) were associated with worse VA. The inner retinal thickness decreased faster in RVO than controls (rate of retinal thinning −0.27 ± 0.09 μm/month vs. −0.08 ± 0.11 μm/month, p = 0.01). Macular ischaemia was associated with a faster rate of retinal thinning (interaction term macular ischaemia*follow-up time, p = 0.04). Conclusion: Inner retinal and photoreceptors’ layers integrity are associated with better visual acuity once CMO resolves. RVO eyes undergo progressive inner retinal thinning after CMO regression, faster in eyes with macular ischaemia.