Regional variations in the relationship between macular thickness measurements and myopia

Abstract

PURPOSE. To investigate the relationship between myopia and macular thickness, as measured by optical coherence tomography. METHODS. A total of 143 normal subjects comprising 80 eyes with high myopia (spherical equivalent [SE] < -6.0 D), 37 eyes with low to moderate myopia (SE between -6.0 and -0.5 D), and 26 nonmyopic eyes (SE > -0.5 D) were analyzed in this cross-sectional study. Total average, foveal, and inner and outer average macular thicknesses measured by the Stratu-sOCT (Carl Zeiss Meditec Inc., Dublin, CA) were compared among the three diagnostic groups. Associations between macular thickness and refractive error/axial length were evaluated by linear regression analysis. RESULTS. The minimum foveal and average foveal (1-mm ring on the OCT retinal thickness map) thicknesses were significantly greater, and the outer ring macular (3-6-mm) thicknesses significantly lower in the high myopic eyes than in the low to moderate myopic and nonmyopic eyes. No significant difference was found in the inner ring (1-3-mm) macular thickness measurements among the groups. There was a positive correlation between the axial length and the average foveal thickness (r = 0.374, P < 0.001). Negative correlations were found between axial length and the average outer ring macular thickness (r = -0.471, P < 0.001) and total average macular thickness (r = -0.311, P < 0.001). CONCLUSIONS. Retinal thickness is related to refractive error/axial length in normal subjects with regional variations in correlation within the 6-mm macular region. Analysis of macular thickness in the evaluation of macular diseases and glaucoma should be interpreted only in the context of refractive errors and the location of measurement. Copyright © Association for Research in Vision and Ophthalmology.