Effect of cyclodeviations on the axis of astigmatism (for patients with superior oblique paresis).

Cyclodeviations may interfere with fusional ability and may also affect the refractive status. If a cyclodeviation is present, the axis of astigmatism determined under monocular viewing conditions will be different from that determined under binocular viewing conditions. The change in the axis should correlate with the amount and direction of the cyclodeviation. We measured the refractive status under monocular and binocular viewing conditions of patients with cyclodeviation of 3 degrees or more and astigmatism of 1.00 D or more. All patients had superior oblique paresis. We then compared the change in the axis of astigmatism to the cyclodeviation measured with the double Maddox rod test. The average change in the axis of astigmatism was 5.0 degrees and the average cyclodeviation was 5.2 degrees. We recommend that all patients with 3 degrees or more of cyclodeviation, 1.00 D or more of astigmatism, and capable of fusion should have their refractive status determined under binocular viewing conditions.