Purpose: To investigate the influence of eye dominancy on vertical strabismus by measuring cyclotorsion angles in cases of age-related small angle vertical strabismus.
Subjects and methods: Subjects comprised 35 vertical strabismus patients with strabismus of ≤ 12 prism who developed strabismus after the age of 50 years (age: 72.5±8.7 years) and from whom fundus photographs were obtained. Strabismus angle was measured using an alternate prism cover test, and subjective cyclotorsion angles were measured using a major amblyoscope. Objective cyclotorsion angles were investigated using disc-fovea angle (DFA; angle created by horizontal lines joining the fovea and central optic disc) on fundus photographs. The dominant eye was determined using the hole-in-the-card method.
Results: Subjective cyclotorsion angle was 7.3±3.9° (n=35), and 23 of these cases were ≥ 6°. DFA was 11.8±4.5° for the right eye and 12.8±4.2° for the left eye (n=35 each). For both eyes, these values were significantly larger than those previously reported for normal elderly groups (p<0.01). FA values were significantly larger for the hypotropia eyes than for the hypertropia eyes (13.3±4.3° and 11.3±4.3°, respectively; p=0.03). There were 21 cases of hypotropia in the left eye and 14 of hypotropia in the right eye. There were 21 left non-dominant eyes and 8 right non-dominant eyes. The remaining 2 cases had bilateral eye dominance. Eye dominancy testing was not conducted on 4 cases. Of the hypotropia eyes, there were approximately twice as many non-dominant eyes as dominant eyes. The side of hypotropia eye, either left or right, was related to whether that eye was the dominant or the non-dominant eye (Fisher's exact test; p<0.05).
Conclusions: In age-related vertical strabismus, DFA was larger than in normal elderly individuals for both eyes and the DFA of hypotropia eyes was larger than that of hypertropia eyes. Hypotropic eye laterality was related to dominant eye laterality.
Nippon Ganka Gakkai Zasshi (J Jpn Ophthalmol Soc) 123: 161-166, 2019.