Risk Factors for Amblyopia in the Vision in Preschoolers (VIP) Study

Abstract

 

Purpose

 

To evaluate risk factors for unilateral and bilateral amblyopia in the Vision in Preschoolers (VIP) Study.

 

Methods

 

3- to 5-year Head Start preschoolers, over-representing children with vision problems, were enrolled in the cross-sectional VIP Study from 5 clinical centers (Berkeley, Boston, Columbus, Philadelphia, Tahlequah). All children had full eye exams done by VIP-certified pediatric optometrists and ophthalmologists. Visual acuity (VA) was tested without correction and retested with full cycloplegic correction when retest criteria were met. Unilateral amblyopia was defined as an inter-ocular difference in best-corrected VA≥2 lines. Bilateral amblyopia was defined as best-corrected VA in each eye <20/50 for 3-year-olds and <20/40 for 4- to 5-year-olds. The odds ratios (ORs) and their 95% confidence intervals (95% CIs) associated with demographic and ocular risk factors were estimated using logistic regression models.

 

Results

 

Among 3869 children, 257(6.6%) had unilateral amblyopia and 225(5.8%) had bilateral amblyopia. Hispanic ethnicity and the presence of strabismus were independently associated with increased risk of unilateral amblyopia. Presence and greater magnitude of significant refractive errors (myopia, hyperopia, astigmatism, and anisometropia) were independently associated with increased risk of unilateral amblyopia (Table 1). Using myopia ≥0.5D, hyperopia ≥2.0D, astigmatism ≥1.0D, anisometropia ≥0.5D, or presence of strabismus, almost all (92%) unilateral amblyopia cases were found. Presence and greater magnitude of both astigmatism and bilateral hyperopia were independently associated with increased risk of bilateral amblyopia (Table 2). Age was independently associated, but gender and ethnicity were not associated with bilateral amblyopia. Using bilateral hyperopia ≥2.0D, or astigmatism ≥1.0D, 82% of bilateral amblyopia cases were found.

 

Conclusions

 

Significant refractive error and strabismus were associated with unilateral amblyopia. Astigmatism and bilateral hyperopia were associated with bilateral amblyopia. These results are consistent with findings from the population-based Multi-ethnic Pediatric Eye Disease and Baltimore Pediatric Eye Disease studies. Screening for refractive error can identify the majority of children at high risk of amblyopia.

 

 

Table 1 Multivariate analysis for risk factors of unilateral amblyopia

 

 

Table 2 Multivariate analysis for risk factors of bilateral amblyopia (N=3869)

 

Keywords: 417 amblyopia • 464 clinical (human) or epidemiologic studies: risk factor assessment