Association between non-invasive liver fibrosis indices and neuroretinal thickness from a nationwide cross-sectional study in South Korea

ObjectiveTo evaluate associations of non-invasive liver fibrosis indices with optical coherence tomography (OCT)-derived retinal nerve fiber layer (RNFL) and ganglion cell-inner plexiform layer (GCIPL) thickness in Korean adults.MethodsThis cross-sectional study used Korea National Health and Nutrition Examination Survey data from 2019-2021. The analytic cohort included 5,830 adults contributing 10,814 eyes after excluding chronic liver disease, ocular disease, and missing or invalid laboratory or ocular data. Primary exposures were fibrosis-4 index (FIB-4) and aspartate aminotransferase-to-platelet ratio index (APRI), standardized to z scores. Outcomes were corrected average RNFL thickness and average GCIPL thickness. Generalized estimating equation models accounted for inter-eye correlation and adjusted for demographic, ocular, cardiometabolic, and lifestyle covariates.ResultsCorrected average RNFL and GCIPL thickness decreased across FIB-4 categories. In fully adjusted models, higher FIB-4 was associated with thinner corrected average RNFL thickness (β=-0.438 µm; 95% CI, -0.679 to -0.197; P<0.001), as was higher APRI (β=-0.270 µm; 95% CI, -0.461 to -0.078; P=0.006). GCIPL associations were weaker but nominally significant. After false discovery rate correction, only FIB-4 and APRI remained significantly associated with corrected average RNFL thickness. RNFL associations persisted after non-linear age adjustment and in survey-weighted participant-level analyses.ConclusionsHigher non-invasive liver fibrosis indices were associated with slightly thinner OCT-derived neuroretinal measurements, most robustly corrected average RNFL thickness. The small effect sizes support population-level epidemiologic interpretation rather than individual-level clinical use.