Are inner nuclear layer ischemic lesions hidden indicators of retinal vein occlusion risk? A case-control study

PURPOSE: To investigate the association between retinal vein occlusion (RVO) and evidence of previous, unnoticed inner nuclear layer (INL) infarction in the fellow eye. METHODS: This prospective case-control study compared the prevalence of INL lesions in the fellow eye of consecutive people with hypertension (PwHTN) with unilateral RVO versus a randomly chosen eye of an age-matched control group of PwHTN without RVO. En face slabs above the outer plexiform layer (OPL) were generated from 6 × 6 fovea-centered optical coherence tomography scans. Cross-sectional scans and en face slabs were surveyed for evidence of active/resolved ischemic INL lesions. RESULTS: 69 PwHTN were included and assigned to two groups, i.e., the RVO group (n = 37; 22 BRVO and 15 CRVO) and the control group (n = 32). There was no inter-group difference regarding age, gender distribution, and background diseases. Resolved INL lesions were more frequent in the RVO group (n = 26) than in the control group (n = 4) (70.3% vs. 12.5%, p < 0.001). BRVO and CRVO cases had similar prevalence of INL lesions in their fellow eyes. Unlike diabetes, ischemic heart disease, and gender, INL lesions were associated with RVO (in the fellow eye) with an odds ratio of 15.7 (95%CI: 4.17–76.73, p < 0.001). CONCLUSION: We identified a substantially higher prevalence of INL lesions in PwHTN with RVO compared to PwHTN without RVO. The atrophic appearance of lesions suggests they may serve as early markers of increased RVO risk in individuals with systemic or cardiovascular predisposing factors.