[Analyze of the accommodative response in myopia anisometropes]

This study is designed to analyze the accommodative hysteresis, accommodative responses between two eyes of anisometropes. The difference of the shape and slope of the accommodative response curves under closed-loop state is evaluated. A comparison study between emmetropes and anisometropes was assessed as well.

It was a case-control study. Forty volunteers, (age from 20 to 31 years) participated in the research. 20 subjects had emmetropia (spherical equivalent +0.37D to -0.25D in both eyes), 20 subjects had anisometropia with spherical power difference ranging from 2.50D to 7.00D between their two eyes. Accommodation taken by objective methods: RE and accommodative response (AR) to 1.00D, 2.00D, 3.00D, 4.00D stimulus were measured objectively by WV-500 binocular infrared optometer (Grand Seiko Co. Japan). The slope of the AR/AS was calculated and compared between different groups.

Under closed-loop state, the higher refractive error eye of anisometropia had most accommodation lag followed by lower eye and emmetropic eye. In stimulus of 3.00D and 4.00D, the differences between higher eye and emmetropic eye were significant (t = 2.055, 2.410; P < 0.05). The differences of the slopes between two eyes of ainisometropes under all conditions were without significant difference (P > 0.05). But the slopes of higher refractive error were lower than that of emmetropoes (t = 2.550, P < 0.05).

The accommodative responses of two eyes of anisometropia are different, the higher eye of anisometropia shows higher accommodation lag. Every non accommodation balance phenomenon showed by anisometropia may be associated either with different accommodation controller gain, or with higher threshold of "ciliary-lens" system or both. It is needed further study to clarify.