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.