Investigation of the change in accommodative response after successful orthoptic therapy in amblyopes

Abstract

Objective To investigate the recovery of accommodative function in former amblyopes with monocular hyperopic anisometropia who had undergone successful orthoptic therapy.Methods In this cross-sectional study, 55 children with monocular hyperopic anisometropia who were former amblyopes and 50 emmetropes were investigated. A SRW-5500 autorefractor was used to measure accommodative response while the children viewed an E target placed at 50, 33 and 20 cm.Accommodative lags were calculated with formula accommodative demand minus accommodative refraction. Data were analyzed with an independent samples t test, a paired t test and a linear correlation analysis. Results At the 20, 33, 50 cm distance, the accommodative lags of the dominant eyes of the normal group were (0.26±0.31), (0.12±0.02) and (0.10±0.01)D, respectively, while the accommodative lags of the non-dominant eyes were (0.27±0.30), (0.17±0.14), and (0.12±0.01)D, respectively. The accommodative lags of the dominant eyes of the monocular former amblyopes at the 3 distances were (0.40±0.14), (0.29±0.09) and (0.17±0.06)D, respectively, and the accommodative lags of the non-dominant eyes were (1.66±0.47), (1.38±0.34) and (1.16±0.34)D, respectively. There was no significant difference in the accommodative lags of the dominant eyes between the former amblyopic and emmetropic groups at all reading distances. The accommodative lags of the non-dominant eyes in the former amblyopes were greater than those of the fellow eyes at the 3 distances. These overall differences were significant in the amblyopic subjects (t=18.731, 22.764, 21.020, P＜0.01). The standard deviations of accommodative responses for the former amblyopes with monocular hyperopic anisometropia were (0.09±0.04), (0.09±0.02), (0.09±0.02)D, respectively at the 3 distances, while those for the dominant eyes of the former amblyopes were (0.04±0.01), (0.04±0.03), (0.04±0.00)D,respectively. The standard deviations of the former amblyopic eyes were greater than those of the fellow eyes at the corresponding reading distance. These differences were significant (t=10.072,10.216, 22.342, P＜0.01). Conclusion The accommodative lags and variability of accommodative responses increase in former amblyopic eyes compare to the dominant fellow eyes and normal eyes in anisometropic subjects. This demonstrates that the recovery of accommodative function in hyperopic anisometropic amblyopes lags behind the improvement of visual acuity. Key words: Accommodation,ocular; Amblyopia; Anisometropia; Hyperopia; Child