Retinal Nerve Fiber Layer Imaging with Spectral-Domain Optical Coherence Tomography: Interpreting the RNFL Maps in Healthy Myopic Eyes

Abstract

PURPOSE: To investigate the association between the distribution profile of the retinal nerve fiber layer (RNFL) bundles and myopia and its impact on interpretation of the RNFL map imaged by a spectral-domain optical coherence tomography (SD-OCT). METHODS: the RNFL of 189 myopic eyes from 103 normal healthy myopic participants was imaged by an SD-OCT. The angle between the long axes of the superotemporal and inferotemporal RNFL bundles determined in the RNFL thickness map (the RNFL distribution angle) and the abnormal area in the RNFL thickness deviation map were measured. The associations between the RNFL distribution angle and the axial length/spherical error, and between the area of abnormal RNFL measurement and each of the following: axial length, spherical error, RNFL distribution angle, average RNFL thickness, optic disc area, and signal strength were analyzed with linear mixed models. RESULTS: The RNFL distribution angle decreased with the axial length (P < 0.011). In the univariate analysis, the area of abnormal RNFL measurement was positively associated with the axial length (P = 0.001); and negatively associated with the RNFL distribution angle (P < 0.001), average RNFL thickness (P < 0.001), optic disc area (P ≤ 0.001), and signal strength (P = 0.026). In the multivariate analysis, the area of abnormal RNFL measurement was negatively associated with the RNFL distribution angle independent of other covariates. CONCLUSIONS: The superotemporal and inferotemporal RNFL bundles converged temporally with increasing myopia, which was associated with an increase in area of abnormal RNFL measurement. The interpretation of the RNFL thickness map in myopic eyes requires careful consideration of the distribution pattern of the RNFL bundles.