Myopia Severity, Axial Length, and Asymmetric Peripapillary Retinal Nerve Fiber Layer Topography: A Cross-Sectional Optical Coherence Tomography Study

Abstract

Background: Myopic axial elongation can alter optic disc geometry and peripapillary retinal nerve fiber layer (RNFL) measurements, complicating glaucoma assessment. Objective: To assess the associations of myopia severity and axial length with quadrant-specific peripapillary RNFL thickness. Methods: This cross-sectional study included 55 eyes from 29 adults aged 17–39 years examined in Padang, Indonesia, during June–July 2025. Mild, moderate, and high myopia groups comprised 23, 18, and 14 eyes, respectively. RNFL thickness was measured with Cirrus HD-OCT and axial length with swept-source optical biometry. Results: Average RNFL thickness declined across mild (102.16 ± 13.16 µm), moderate (98.42 ± 10.58 µm), and high myopia (90.83 ± 8.18 µm; p = 0.017). The superior and inferior quadrants were thinner in high myopia, whereas temporal RNFL was thicker (71.88 ± 12.83 µm in mild versus 80.12 ± 11.69 µm in high myopia). Axial length correlated with spherical equivalent (r = −0.661, p < 0.001) and temporal RNFL thickness (r = 0.284, p = 0.036). The ISNT rule was violated in 85.7% of highly myopic eyes. Conclusion: Greater myopia and longer axial length were associated with asymmetric RNFL topography, including vertical thinning and relative temporal thickening. Peripapillary OCT findings in myopic eyes should be interpreted alongside axial length and other clinical evidence.