Abstract
Purpose: :
To determine the prevalence of anisometropia and the relation between anisometropia and amblyopia in children who are members of a Native American Tribe with a high prevalence of astigmatism.
Methods: :
: Subjects were 1,016 children 4–13 years of age who attended elementary schools on the Tohono O’Odham Reservation and who did not have strabismus or ocular abnormalities other than refractive error, based on a comprehensive eye examination. Anisometropia was defined, based on cycloplegic autorefraction confirmed by retinoscopy, as interocular difference (IOD) ≥ 1.00 diopter (D) in spherical equivalent (SE) or IOD ≥ 1.50 D cylinder (cyl), as in studies from the Pediatric Eye Disease Investigator Group. Amblyopia was defined as an interocular difference in best–corrected acuity ≥ 2 logMAR lines, measured with ETDRS charts at 4 m.
Results: :
Among the 1,016 children, 117 (11.5%) had anisometropia. Of these, 84 (71.7%) were wearing glasses or, by parental report, had worn glasses in the past. There was no correlation between prevalence of anisometropia and age. SE–only anisometropia was present in 37 children (3.6%), cyl–only anisometropia in 51 (5.0%), and SE and cyl anisometropia in 29 (2.9%). There was no significant difference in the proportion with SE anisometropia (with or without cyl anisometropia) (6.5%) vs the proportion with cyl anisometropia (with or without SE anisometropia) (7.9%). Among the 970 children with best–corrected acuity results for both eyes, 83 (8.6%) had amblyopia. The proportion of subjects with amblyopia was greater among anisometropes (33/111, 29.7%) than among non–anisometropes (50/859, 5.8%) (X2 = 68.8, p<0.001). Although the prevalence of amblyopia was greater among SE–only anisometropes (13/37, 35.1%) than among cyl–only anisometropes (11/46, 23.9%), this difference was not statistically significant.
Conclusions: :
The prevalence of anisometropia remains relatively constant (∼11.5%) across age in this population. Prevalence of amblyopia was relatively low (29.7%) among anisometropes, perhaps because 71.7% had been treated previously with spectacles.
Keywords: amblyopia • astigmatism • clinical (human) or epidemiologic studies: prevalence/incidence