Accommodation in astigmatic eyes.

PURPOSE: To investigate the effect of target chart contours and the severity of astigmatism on accommodation in astigmatic eyes. METHODS: The accommodative responses of 30 subjects were measured with an automated refractometer (Canon RK-1) using star pattern and bar pattern targets. RESULTS: The mean accommodative response was greatest when the bar pattern was parallel to the stronger principal meridian of the eye, followed by the star pattern and the bar pattern parallel to the weaker meridian on both meridians. Similar results were obtained in subjects with astigmatism greater or less than 1.25 D. The mean slopes of AR/AS plots decreased in the same order as the accommodative response and the change was significant in subjects with astigmatism exceeding 1.25 D. In addition, about one-third of the subjects showed a consistent decrease in astigmatism with accommodation. CONCLUSIONS: These results indicate that the type of target chart and the severity of astigmatism influence the accommodative response.

[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.