Purpose: Many children with unilateral amblyopia do not achieve full recovery of vision with conventional amblyopia treatment strategies, such as patching therapy. A defocussed retinal image caused by poor accommodation may limit treatment success. The primary aim of this study was to evaluate accommodative performance of the amblyopic eye in monocular and binocular viewing conditions and to compare it with the dominant eye and the eyes of control subjects.;Methods: Accommodative performance of 38 children with unilateral amblyopia and 25 visually-normal children from 3 to 13 years of age was assessed using a modified version of Nott dynamic retinoscopy, while the subjects viewed an animated movie presented on an LCD screen at target vergences of 2D, 3D, and 4D. All study procedures were performed while the subjects were in their habitual viewing state, with or without spectacle correction. Accommodative response and accommodative demand were adjusted to account for uncorrected refractive errors. Accommodative lag was calculated by taking the difference between total accommodative response and total accommodative demand.;Results: Mean inter-ocular difference in accommodative lag between amblyopic and dominant eyes in monocular viewing was .49±0.57D in the 180° meridian and 0.54±0.64D in the 90° meridian, and this difference increased significantly with increasing total accommodative demand. 5%, 47%, and 58% of amblyopic subjects had monocular accommodative lags in the amblyopic eye falling outside the upper 95% confidence limit of monocular accommodative lag in either meridian in the better eye of control subjects (1.31D, 1.76D, and 2.29D) at target vergences of 2D, 3D, and 4D, respectively. The accommodative stimulus-response function of the dominant eye of amblyopic subjects was also found to be significantly different from the better eye of control subjects.;Conclusions: Young children with unilateral amblyopia have higher monocular accommodative lags in the amblyopic eye than the dominant eye and the eyes of control subjects. This error increases with higher accommodative demands. These results imply that retinal image defocus in the amblyopic eye increases during patching therapy in some individuals, which may limit treatment success. Therefore, accommodative performance should be considered in the clinical management of children with unilateral amblyopia.
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