ASSOCIATIONS BETWEEN CHOROIDAL ALTERATIONS AND EARLY NEURODEGENERATION IN DIABETES WITHOUT DIABETIC RETINOPATHY

PURPOSE: To identify associations between choroidal alterations and the reduction of peripapillary retinal nerve fiber layer (pRNFL) thickness in diabetes without diabetic retinopathy (nondiabetic retinopathy, NDR). METHODS: This retrospective cross-sectional study included 143 eyes from 83 patients with NDR and 124 eyes from 82 matched healthy controls. Ultra-widefield swept-source optical coherence tomography angiography was used to automatically measure retinal and choroidal thickness (ChT), retinal vascular density, and choroidal vascular metrics. Data were analyzed using Student's t-tests, generalized estimating equations, and generalized linear mixed models. RESULTS: Patients with NDR exhibited significant reductions in perifoveal ChT (e.g., perifoveal inferior region: 253.42 ± 86.59 µm vs. 281.01 ± 80.25 µm, P = 0.026 in GEE test) compared with the controls. The NDR group showed a significant decrease in the choroidal vascular index (P = 0.012 in GEE test), and an increase in the choroidal stromal index (P = 0.012 in GEE test). The average pRNFL thickness significantly decreased in patients with NDR (114.58 ± 11.88 µm vs. 120.25 ± 16.36 µm, P = 0.005 in GEE test). The thickness of the outer nuclear layer and total retina significantly decreased in patients with NDR (P < 0.05). In multivariate models, ChT was significantly correlated with pRNFL thickness (β = 0.041, P = 0.001), even after adjusting by confounding factors (β = 0.056, P = 0.001). CONCLUSION: In NDR, there were decreases in ChT, choroidal vascular index, pRNFL thickness, and outer nuclear layer thickness. The reduction in ChT was independently associated with the reduction in pRNFL thickness, suggesting that ChT could serve as a predictor of retinal neurodegeneration in NDR.