Retinal nerve fiber layer thickness profile in an Iranian adult population

This is the authors' abstract. We don't add key points for this paper.

To determine the distribution of retinal nerve fiber layer thickness (RNFL) and its associated factors in a normal adult population using Spectralis spectral-domain (SD) optical coherence tomography (OCT). This research was conducted utilizing data from the third phase of the Shahroud Eye Cohort Study. Participants were selected from Shahroud City through a multi-stage cluster sampling technique. Uncorrected and best-corrected visual acuity, as well as refraction, were assessed for all participants. Subsequently, each individual underwent slit-lamp examinations conducted by an ophthalmologist. Following pupillary dilation with tropicamide 1% drops, fundoscopic examinations were carried out, and OCT imaging was performed using a Heidelberg Spectralis OCT device. A total of 3,700 eyes from 2,102 participants were included in this report. The average global RNFL thickness recorded in this study was 100.3 ‎µm‎ (95% CI: 99.9-100.7). When analyzed by sex, the average global RNFL thickness was 99.5 ‎ ‎µm‎ (95% CI: 98.9-100.1) for men and 100.9 ‎µm‎ (95% CI: 100.3-101.5) for women. Utilizing a multiple generalized estimating equations (GEE) model, the global RNFL thickness demonstrated a direct association with body mass index (β = 0.11; p = 0.013), corneal radius of curvature (β = 5.27; p < 0.001), and macular volume (β = 7.64; p < 0.001) while showing an inverse relationship with axial length (β=-2.29; p < 0.001), central macular thickness (β=-21.39; p = 0.002), and the presence of diabetes (β=-1.09; p = 0.009). The RNFL thickness profile within a normative cohort aged 50 to 74 years was demonstrated using Spectralis SD-OCT imaging. Beyond biometric indices, it is crucial to consider certain systemic factors that may influence RNFL thickness.