Foveal function in children treated for amblyopia

Abstract

Purpose: This study aimed to evaluate foveal function, using three different methods, in children treated for monocular amblyopia. Methods: A sample of 24 otherwise healthy children with treated amblyopia and an age-matched control group of 25 healthy children were examined for best corrected visual acuity (BCVA) using a standard decimal (KM) chart and the computerized TriVA method at 50% and 10% contrasts. Foveal function was also measured with the rarebit fovea test (RFT), which is included in the rarebit perimetry program package. This test uses very small and bright dots against a dark background. The result is expressed as mean hit rate (MHR). Results: Amblyopic eyes showed significantly lower BCVA when evaluated with the KM chart and with the TriVA test at different contrast levels, compared with both fellow eyes and control eyes. No statistically significant difference between amblyopic and fellow eyes was found when foveal function was evaluated with the RFT (median MHRs 91.5% and 94.5%, respectively), although results for both amblyopic and fellow eyes were statistically lower than those of the control group (median MHR 97%) (p = 0.001 and p = 0.046, respectively). This might indicate that the RFT provides different information about foveal function than conventional VA tests. Conclusions: The findings in the current study accord with those of other studies reporting abnormalities in the fellow eyes of previously treated amblyopic patients. These findings may reflect a general disturbance in the visual system rather than a monocular adaptation to refractive error or ocular motor disturbance. © 2009 Acta Ophthalmol.