Purpose:
To determine the utility of anisometropia and stereoacuity (SA) in predicting subtypes of amblyopia in children who are members of a Native American Tribe with a high prevalence of astigmatism.
Methods:
Subjects were 952 children 4-13 years of age who attended school on the Tohono O’odham Reservation and who did not have non-refractive ocular abnormalities, based on an eye examination, with cycloplegic refraction. Monocular best-corrected visual acuity was measured in each eye with ETDRS letter charts at 4 m and best-corrected stereoacuity (SA) was measured with the Randot Preschool Stereoacuity test at 40 cm. Parents reported history of spectacle wear (HxRx). Anisometropia was classed as either being spherical equivalent (SEAniso) or cylindrical (CylAniso) by vector methods.
Results:
Children were classified as Non-Amblyopic (NA), with better seeing eye (BSE) acuity of 20/32 or better, and less than 2 logMAR Line Difference (2LD) between eyes (n=556); Unilateral Amblyopia with BSE 20/32 or better, ≥ 2LD; Symmetric Bilateral Amblyopia with both eyes worse than 20/32 and <2LD; Asymmetric Bilateral Amblyopia with both eyes worse than 20/32 and ≥2LD. Multinomial logistic regression was used to predict subtypes of amblyopia by SA, SEAniso, and CylAniso after adjusting for HxRx and age. Z score probabilities are shown in the Table, with No Amblyopia (n=556) as comparison group:
Conclusions:
For all subtypes of amblyopia, stereoacuity has significant predictive value. However, for amblyopia in which one eye sees at least 20/32, Spherical Equivalent Anisometropia is most predictive, while for cases of bilaterally reduced vision in this population, Cylinder Anisometropia is most predictive of the presence of amblyopia.
Keywords: amblyopia • astigmatism • clinical (human) or epidemiologic studies: risk factor assessment