Abstract
Purpose: :
To evaluate the accuracy of binocular and monocular accommodation in children with unilateral amblyopia compared to a typically-developing age-matched cohort.
Methods: :
Subjects between 3 and 10 years of age with treated or untreated unilateral amblyopia (A) and an age-matched group of typically-developing children (TD) had their accommodation measured in their habitual refractive state using an automated Nott retinoscopy system. They viewed a cartoon presented on an LCD screen at 2, 3, and 4 diopter stimulus positions. Accommodative response functions (ARF) were plotted for each eye under binocular and monocular viewing conditions. The slopes of the ARF and average accommodative lag across the three stimulus positions were derived. The mean between-eye difference in slope and the mean between-eye difference in average lag under binocular viewing conditions were compared with monocular viewing, to control for any effects of uncorrected or partially corrected refractive error. Statistical analyses were adjusted with Bonferroni correction.
Results: :
The mean difference in slope between the eyes was not significantly different across binocular and monocular conditions for either A (p=0.32) or TD subjects (p=1.00). The mean difference in lag between the eyes was significant for A subjects (mean diff. = 0.31 D monoc>binoc; p=0.04), but not for TD subjects (p=0.20).
Conclusions: :
Amblyopic children demonstrated higher relative lags of accommodation in their amblyopic eyes under monocular conditions than binocular conditions, but exhibited equal ARF slope differences. TD subjects demonstrated equal differences in accommodative lags and ARF slopes for the two viewing conditions. Therefore, the potential impact of increased blur due to high monocular lag in the amblyopic eye under monocular viewing conditions should be considered during patching therapy.
Keywords: amblyopia • accommodation • visual development