The Association Between Amblyopia and Anisometropia in Intermittent Exotropia

ABSTRACT

PURPOSE: To determine the frequency of amblyopia and anisometropia in intermittent exotropia and to evaluate the relationship between anisometropia and amblyopia. METHODS: The medical records of 471 intermittent extotropia patients, who were followed up over a period of 6 months and ranged from 3 to 15 years of age had been retrospectively reviewed. Anisometropia patients, who had either spherical or cylindrical anisometropia of more than 1.00D, were divided into 4 groups spherical hyperopic anisometropia (SHA), spherical myopic anisometropia (SMA), cylindrical hyperopic anisometropia (CHA), and cylindrical myopic aniometropia (CMA). RESULTS: The frequency of amblyopia in the intermittent exotropia group was 41/471 (8.7%). Amblyopia results in a significant increase in the incidence of anisometropia and a decrease in binocular function when compared with non-amblyopic patients. In the amblyopia group, 14 patients had anisometropia (34.1%) consisting of 2 patients with spherical myopic anisometropia (SMA), 2 patients with spherical hyperopic anisometropia (SHA), 2 patients with cylindrical myopic anisometropia (CMA) and 8 patients with cylindrical hyperopic anisometropia (CHA). In the anisometropia group (n=56) 14 patients (25.0%) had amblyopia and in the non-anisometropia group (n=415) 27 patients (6.5%) had amblyopia. CONCLUSIONS: Intermittent exotropia is susceptible to amblyopia, especially when combined with anisometropia. Among the 4 types of anisometropia, cylindrical hyperopic anisometropia has a higher risk for developing amblyopia.