Incidence of Amblyopia in Intermittent Exotropia
Kathy Smith, O.C.(C.), COMT, Terry John Kaban, O.C.(C.) and Robert Orton, M.D.
We retrospectively analyzed the visual acuity of 600 patients with primary intermittent exotropia to determine the incidence of amblyopia. From this group 412 (68.7%) patients had equal vision between the two eyes, 111 (18.5%) patients had unequal vision of one line difference between the eyes and 77 (12.8%) patients had functional amblyopia. Reduced vision in the amblyopic group consisted of a median and average acuity of 6/12 and mild amblyopia occurred most frequently present in 56 (72.7%) cases. Significant refractive error in the amblyopic group included 16 cases with anisometropia, four with myopia and five with astigmatism/mixed astigmatism. The prevalence of amblyopia was similar among the different types of intermittent exotropias, however patients with a constant manifest exotropia at distance were more likely to exhibit amblyopia (21%) than those with an intermittent exotropia (9.3%). The frequency of reduced stereoacuity was not significant between the amblyopia group (67%) and non-amblyopic group (60%).
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