PREVALENCE OF PALPEBRAL FISSURE ASYMMETRY IN WHITE PERSONS

PURPOSE: Because palpebral fissure asymmetry in horizontal gaze is rep ortedly common in otherwise normal persons, we determined the prevalen ce of physiologic palpebral fissure asymmetry for primary and horizont al gazes. METHODS: We measured the palpebral fissure height of both ey es of 88 healthy white subjects. Measurements were obtained with high- resolution videography, with the eyes in primary position, in 45-degre e right gaze, and in 45-degree left gaze. RESULTS: Of the 88 subjects, 36 (41%) were male and 52 (59%) were female. The ages ranged from 12 to 50 years, with a mean of 32.5 +/- 9.0 years. When a criterion of eq ual to or greater than 1 mm was used, the prevalence of physiologic pa lpebral fissure asymmetry was 5.7% (five of 88) in primary gaze, 18.2% (16 of 88) in right gaze, and 14.8% (13 of 88) in left gaze. The larg est observed palpebral fissure asymmetry was 2.1 mm. After correcting for any existing fissure asymmetry in primary gaze, two tailed trivari ate analysis of variance showed that the fissure of the adducting eye tended to be wider. The mean increase in the palpebral fissure of the adducting eye was 0.12 mm for right gaze (P = .052) and 0.13 mn for le ft gaze (P = .034). Additionally, a chi(2) test indicated that the occ urrence of wider adducting eye in both right and left gazes was highly significant (P = .0023). CONCLUSIONS: In this sample of white subject s, palpebral fissure height asymmetry increased in horizontal gaze to the right anal to the left, which is in part because of a tendency of the adducting eye to widen slightly. In contrast to previous reports, the prevalence of palpebral fissure asymmetry was low, and the abducti ng eye did not widen significantly.