ASSOCIATIONS BETWEEN CHOROIDAL ALTERATIONS AND EARLY NEURODEGENERATION IN DIABETES WITHOUT DIABETIC RETINOPATHY: INSIGHTS FROM ULTRA-WIDEFIELD OCTA IMAGING

Abstract

Purpose: To identify associations between choroidal alterations and the reduction of peripapillary retinal nerve fiber layer (pRNFL) thickness in diabetes without diabetic retinopathy (non-diabetic retinopathy, NDR). Methods: This retrospective cross-sectional study included 143 eyes from 83 NDR patients 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 t-tests, generalized estimating equations and generalized linear mixed models. Results: NDR patients exhibited significant reductions in perifoveal ChT (e.g., perifoveal inferior region: 253.42 ± 86.59μm vs. 281.01 ± 80.25μm, P = 0.026 in GEE-test) compared to the controls. The NDR group showed significant decrease in the choroidal vascular index (P = 0.012 in GEE-test), and increase in the choroidal stromal index (P = 0.012 in GEE-test). The average pRNFL thickness significantly decreased in NDR patients (114.58 ± 11.88μm vs. 120.25 ± 16.36μm, P = 0.005 in GEE-test). The thickness of outer nuclear layer (ONL) and total retina significantly decreased in NDR patients (P < 0.05). In multivariate models, ChT was sigficantly 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 ONL 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.