ACCOMMODATION IN ASTIGMATIC EYES

Purpose. To investigate the effect of target chart contours and the se verity of astigmatism on accommodation in astigmatic eyes. Methods. Th e accommodative responses of 30 subjects were measured with an automat ed refractometer (Canon RK-1) using star pattern and bar pattern targe ts. Results. The mean accommodative response was greatest when the bar pattern was parallel to the stronger principal meridian of the eye, f ollowed 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/A S 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 d ecrease in astigmatism with accommodation. Conclusions. These results indicate that the type of target chart and the severity of astigmatism influence the accommodative response.