Longitudinal Interocular Difference of Refractive Error in Children with Accommodative Esotropia

Abstract

Purpose: : Anisometropia is associated with increased risk for accommodative esotropia (ET) in hyperopic children (Weakley & Birch, 2000). The aim of this study was to evaluate longitudinal changes in anisometropia and its association with visual deficits in children with accommodative ET.

Methods: : Retrospective cohort study of children with accommodative ET. Eligibility criteria included: initial visit after 1 year and before 4 years of age and final visit after 7 years of age; with full cycloplegic refraction correction on first follow-up examination. Cycloplegic refractions culled from medical records were converted into power vector components: M (spherical equivalent), J0 (positive J0 indicates with-the-rule astigmatism) and J45 (oblique astigmatism) in diopters (D). Unilateral amblyopia was defined interocular visual acuity difference ≥0.2 logMAR (2 lines); bilateral amblyopia was defined as visual acuity worse than 0.30 logMAR (20/40) in both eyes.

Results: : The study included 87 patients. Before 7 years of age, mean M did not change significantly, and ranged from 4.5 to 5.7D. At all ages, mean J0 ranged from 0.1 to 0.5D, while mean J45 was within ±0.1D. The prevalence of anisometropia (M≥1D) was 26% at the initial visit and 32% at the final visit; only 60% had no anisometropia at both the initial and last visit. Among the 23 children who had anisometropia on the initial visit, 70% (16/23) had persistent anisometropia ≥1D throughout ≥3 years follow-up; 30% had anisometropia that diminished to <1.00 D by the final visit. In addition, 12 children who did not have anisometropia on the initial visit developed anisometropia during follow up. Interocular difference in M at the final visit was highly correlated with that at the initial visit (r= 0.78, p<0.001); that is, children who had large amounts of anisometropia tended to have persistent anisometropia. At the final visit, 3% (3/87) had bilateral amblyopia, 29% (25/87) had unilateral amblyopia, and 65% (56/87) were non-amblyopic. Risk for amblyopia was associated with anisometropia at the initial visit (OR=3.46; CI₉₅=[1.71,6.99]; p<0.001) and at the final visit (OR=2.56; CI₉₅=[1.42, 4.61]; p=0.002).

Conclusions: : The prevalence of anisometropia among children with accommodative ET was approximately a factor of 10 higher than the prevalence in population-based studies (1.6-4.3%). In children with accommodative ET, anisometropia develops dynamically. Anisometropia at the initial visit is highly associated with later anisometropia and elevated risk for amblyopia.

Keywords: refractive error development • strabismus • esotropia and exotropia