Fixation preference and visual acuity testing in a population-based cohort of preschool children with amblyopia risk factors

Abstract

Purpose: To compare the clinical assessment of fixation preference (FP) to visual acuity (VA) in a population-based sample of preschool children with amblyopia risk factors.

Design: Evaluation of diagnostic test in a population-based study.

Participants: 243 children with anisometropia and/or strabismus, aged 30 to 72 months, living in Los Angeles County, CA [corrected]

Methods: Before measuring VA, FP testing was performed at near and usually without correction, using the binocular fixation pattern in children with strabismus >10 prism diopters (Delta), or the induced tropia test for children with strabismus <or=10Delta or without strabismus. We determined the sensitivity and specificity of FP testing for predicting unilateral amblyopia, defined by optotype VA, among children with amblyopia risk factors.

Main outcome measure: Grade of FP.

Results: Sensitivity of FP testing for amblyopia among children with anisometropia was 20% (9/44) and specificity was 94% (102/109). Among strabismic children, sensitivity was 69% (9/13; worse in children 30-47 than 48-72 months old) and specificity was 79% (70/89), with similar findings for esotropia and exotropia.

Conclusion: The ability of FP testing to correctly identify amblyopia in preschool children with amblyopia risk factors is poor. Clinicians should be wary of using FP as a surrogate measure of interocular difference in VA in young children.

Financial disclosure(s): The authors have no proprietary or commercial interest in any materials discussed in this article.

Figure 1

Fixation preference testing protocol for the Multi-Ethnic Pediatric Eye Disease Study. BFP = binocular fixation pattern; ITT = induced tropia test; OD = right eye; OS = left eye