AC/A Ratio Measured by Modified Gradient Method.

Lee, Jong Bok; Bum, Sang Gyun

Original Article

Journal of the Korean Ophthalmological Society 1987;28(4):799-804.
Published online April 1, 1987.

AC/A Ratio Measured by Modified Gradient Method.

Jong Bok Lee, Sang Gyun Bum

Department of Ophthalmology, Yonsei University, College of Medicine, Seoul, Korea.

Modified Gradient Method 로 측정한 AC / A Ratio

이종복(Jong Bok Lee),범상균(Sang Gyun Bum)

Abstract

A clinical study on the AC/A ratio with 125 normal persons was performed by modified gradient method. AC/A ratio is a convergence response of an individual to a unit stimulus of accommodation. Through many studies on the AC/A ratio, the normal range of the AC/A ratio was 3 delta/D ~ 5 delta/D. The AC/A ratio can be changed by some drugs. The AC/A ratio is high in divergence excessive exotropia, pseudodivergence exotropia and non-refractive accommodative esotropia; on the other hand, the AC/A ratio is low in convergence insufficiency exotropia. Methods for the determination of the AC/A ratio are heterophoria method, gradient method, fixation disparity method. This study was performed by modified gradient method due to easy application. The mean of the AC/A ratios in this study was 4.55 delta/D, and the AC/A ratios ranged from 0.5 delta/D to 9.6 delta/D. 95 percentile ranged from 3.01 delta/D to 6.09 delta/D. The AC/A ratio in this study seems not to be correlated with age, sex and interpupillary distance.