Evaluation of Peripapillary Retinal Nerve Fiber Layer Thickness in Myopic Eyes by Spectral-domain Optical Coherence Tomography

Abstract

To investigate the influence of myopia on peripapillary retinal nerve fiber layer (RNFL) thickness using Cirrus optical coherence tomography (OCT) in normal eyes. Ninety-eight eyes of normal participants with various degrees of myopia were recruited in this study. The RNFL thickness was measured with high-definition (HD), spectral-domain Cirrus OCT (Cirrus HD-OCT; Carl Zeiss, Dublin, CA). The association between RNFL thickness and its spherical equivalent was evaluated with linear regression analysis. The RNFL thickness was 119.2±16.8 μm, 117.1±16.8 μm, 75.9±16.1 μm, and 64.9±9.8 μm in the superior, inferior, temporal, and nasal quadrants, respectively, with an average thickness of 94.3±8.6 μm. The mean RNFL thickness was thinner in highly and moderately myopic eyes (93±7.9 μm and 92.6±7.7 μm, respectively, P=0.0001) compared with low myopic eyes (102.2±9 μm). A significant linear correlation was found between the spherical equivalent and the RNFL thickness in the superior (r=0.386, P=0.0001) and inferior quadrants (r=0.448, P=0.0001), and the average RNFL thickness (r=0.373, P=0.0001). Myopia can be a confounding factor in the assessment of RNFL thickness attributed to its influence on the RNFL thickness. Therefore, we recommend a careful interpretation of RNFL data, especially those obtained from eyes with moderate-to-high myopia.