Abstract
Purpose: :
To study binocular functions, ratio of sensor and motor eye dominance, and objective accommodation response (OAR) in patients with acquired anisomyopia.
Methods: :
Study included 57 patients with acquired anisomyopia, aged 13-25 years. Sensor dominance was estimated using Worth 4-dot test. Motor dominance was estimated using Howard-Dolman stereoacuity test for the far sight and mirror-test for the near sight.OAR was measured on binocular autorefracto/keratometer WR-5100K (Grand Seiko Co., Ltd., Japan).
Results: :
Mean spherical refraction equivalent (SRE) of the eyes with lower myopia was -2.32D. In the eyes with higher myopia, it was -6.56D. Refraction difference between paired eyes ranged from 1.5D to 5.25D. In 63.6% of all cases, right eye had stronger power of refraction (PR) than left eye. When anisometropic difference was ≤3.0D, incidence of dominance of the eyes with stronger PR versus the eyes with lower PR was similar, 41.9%. Whereas when anisometropic difference was >3.0D, dominance of the eyes with higher myopia was observed 2.4 times more incidentally than of the eyes with lower myopia. Dominance of the right eye was observed in 76% of all cases. In 100% of the cases, motor dominance both for the far sight and for the near sight, was seen in the eyes with lower PR. In patients with isomyopia, monocular response (MR) and binocular response (BR) at 33-cm distance were symmetrical. Myopes also showed decreased OAR, as compared to the calculated norm (1.5D±0.09 D instead of 3.0D). In acquired anisomyopia, BR was significantly lower in the eyes with lower PR than in the isomyopic eyes but with greater PR (-2.14±0.11D, p<0.05). While MR (with occluded fellow eye) was found to be the same, -1.96±0.12D. In terms of the sensor dominance, difference between the eyes appeared even more substantial: BR in the dominant eyes showed -2.18±0.12D, which was significantly greater than in the non-dominant eyes, -1.70±0.13D (p<0.05).
Conclusions: :
In acquired anisomyopia, eyes with higher myopia showed sensor dominance, whereas eyes with lower myopia showed motor dominance. In anisomyopia with binocular fixation, sensor-dominant eyes accommodated more accurately.
Keywords: accommodation • binocular vision/stereopsis • myopia