Distribution of axial combinations in astigmatism patients.

A total of 527 astigmatic patients were examined for their axial distribution. The values taken for all eyes together confirmed the preponderance of "+" cylinder at an axis of 90 degrees. However, only a small percentage of patients demonstrated a 90 degree axis for each eye separately. Mirroring and parallel axes were more common and an asymmetric axial distribution was found most frequently. The influence of lid pressure on the development of astigmatism thus seems, according to our findings, unlikely. Genetic factors are more probable.