Normative Percentiles and Age-Related Change Points for RNFL and GCIPL Thickness in Healthy Korean Adults Based on Cirrus HD‑OCT

Purpose To generate decade-specific normative percentiles for Korean adults and identify age-related change points in retinal nerve fiber layer (RNFL) and ganglion cell-inner plexiform layer (GCIPL) thickness using Cirrus HD optical coherence tomography (OCT).Methods Cross-sectional, population-based study of 8,558 healthy Korean adults from the Korea National Health and Nutrition Examination Survey (KNHANES) 2017–2021. Cirrus HD-OCT imaging used Optic Disc Cube 200 × 200 protocol for RNFL and Macular Cube 512 × 128 protocol for GCIPL measurements. Simple linear regression change-point (SLRCP) analysis identified age-related change points. Decade-specific percentiles (5th, 25th, 50th, 75th, 95th) were calculated.Results Cohort included 4,654 women (54.4%) and 3,904 men (45.6%) aged 47.4 ± 13.5 years. Mean RNFL thickness was 95.7 ± 9.1 μm, and GCIPL thickness was 82.7 ± 5.8 μm. Linear regression showed significant age-related decline: RNFL at −0.116 μm/year (95% CI, −0.133 to −0.100; p < .001) and GCIPL at −0.044 μm/year (95% CI, −0.055 to −0.034; p < .001). Women showed thicker RNFL (96.6 vs. 94.9 μm; p < .001), while men had thicker GCIPL (83.0 vs. 82.4 μm; p < .001). SLRCP analysis identified change points with accelerated thinning: GCIPL 51 years (slopes: +0.056 to −0.248 μm/year) and RNFL at 52 years (slopes: −0.079 to −0.240 μm/year). Median RNFL declined from 97 μm (20–29 years) to 87 μm (80–89 years) and GCIPL from 82 μm to 76 μm.Conclusion RNFL and GCIPL demonstrate nonlinear age-related thinning with accelerated decline beginning in the fifth to sixth decades. These decade-specific normative values and change points provide population- and device-specific references which improve diagnostic accuracy.