[Accommodation in ametropia and the effect of targets on astigmatism]

Measurements of accommodative responses in 28 astigmatic eyes (22 patients, 19-32 years of age) were made with an objective Auto Refkeratometer (Canon, RK-1). We constructed an actual target representative instrument with a star burst chart and a fine line chart, and attached this instrument to the Auto Refkeratometer. The fine line chart was turned around the sight line of the eye at a fixed distance. The amount of mean accommodative responses decreased in the following order; the fine line chart parallel to the first principal meridian of subjects, the star burst chart, the fine line chart parallel to the second principal one. This tendency was also shown in cases of subjects with astigmatism less than 1.25 diopters. The slopes of mean accommodative response curves reduced in the similar order as above, significantly in the cases of astigmatism over 1.25 diopters. These results suggest that target charts for accommodation and the degree of astigmatism have influence on the amount of accommodative response and the slope of its curve.