Quantitative forced cyclorotation testing using a smartphone

Abstract

Purpose: To evaluate the utility of a quantitative forced cyclorotation test using a smartphone in patients with unilateral superior oblique palsy. Methods: Twenty-nine patients who underwent muscle surgery for superior oblique palsy were included. With patients under anesthesia prior to surgery, the 12 and 6 o’clock positions of the limbus were marked, the globe was maximally excyclorotated and incyclorotated, and photographs of the globe were taken in each position. The maximum angle of rotation was read by two masked observers using two different smartphone applications. Maximum excyclorotation and incyclorotation were compared between patients with superior oblique palsy alone and patients with both superior oblique palsy and intermittent exotropia; associations were evaluated regarding age at surgery, angle of hypertropia, and cyclotorsion on fundus photographs. Results: The intraclass correlation coefficient between the two readers was 0.989. The maximum excyclorotation of affected eyes was significantly greater than that of the fellow eyes (46.1 ± 9.9° vs. 41.7 ± 7.6°; p = 0.040). Maximum incyclorotation did not differ between the two eyes. The maximum excyclorotation of affected eyes of 18 patients with unilateral superior oblique palsy alone was significantly greater than that of the fellow eyes (47.0 ± 9.5° vs. 39.4 ± 6.3°; p = 0.010). The maximum excyclorotation of affected eyes of 11 patients with both superior oblique palsy and intermittent exotropia was similar to that of the fellow eyes (44.5 ± 10.9° vs. 45.5 ± 8.3°). Maximum incyclorotation did not differ according to group or eye. Maximum excyclorotation did not differ according to age at surgery, angle of hypertropia, or cyclotorsion on fundus photographs. Conclusions: New forced cyclorotation tests using a smartphone quantitatively assess the passive range of cyclorotation, and detect bilateral differences, particularly in patients with unilateral superior oblique palsy alone. © 2020 Korean Ophthalmological Society (KOS). All rights reserved.