Visual performance fall-off with eccentricity in myopes versus emmetropes

Abstract

PurposeTo compare the central and peripheral visual performance of myopic and emmetropic eyes. MethodsThirty emmetropic (−0.50 to +0.50D) and 60 myopic (−2.00 to −9.62D) subjects were recruited. Resolution acuity was assessed at central and 12 peripheral retinal locations (±10°, ±20°, ±30° along the horizontal meridian, and ±10°, ±20°, ±25° along the vertical meridian) using a modified version of the Contrast Acuity Assessment test at low (δl/l=14%) and high (δl/l=100%) contrast levels. The central and peripheral data were analysed using univariate and repeated-measures analysis of variance respectively. In addition, asymmetries in visual function, along both the horizontal (temporal versus nasal) and vertical (superior versus inferior) meridians, were investigated. ResultsWhen analysed in terms of acuity fall-off with eccentricity, repeated measures ANOVA exhibited a statistically significant difference in peripheral visual performance between refractive groups for high contrast stimuli (p=0.025), with a more rapid fall-off in myopes compared to emmetropes. Nasal and superior retinal regions performed better than temporal (high contrast: p<0.001, low contrast: p<0.001) and inferior (high contrast: p<0.001, low contrast: p=0.003) regions for both refractive groups, consistent with differences between quadrants in neural cell density reported by histological studies. ConclusionThe myopic patients evaluated in this study exhibited reduced peripheral visual performance compared to their emmetropic counterparts when assessed using the Contrast Acuity Assessment test at high contrast level.