Prevalence of Strabismus in Individuals on the Autism Spectrum: A Meta-analysis

Background and ObjectivesStrabismus, a misalignment of the eyes, is an important risk factor for amblyopia and visual impairment in the pediatric population. Several studies have reported an increased likelihood of strabismus in persons on the autism spectrum, but prevalence estimates in this group vary greatly. MethodsWe searched multiple databases to identify peer-reviewed articles published in English through November 1, 2020 that provided estimates of strabismus prevalence in autistic individuals. Prevalence estimates were synthesized using Bayesian random-effects meta-analysis, and sensitivity analysis was also performed using only the subset of studies that recruited participants from non-ophthalmologic settings and identified strabismus using structured ocular exams. Bayesian meta-regression was used to assess potential moderators of prevalence across studies. ResultsA total of 151 nonduplicate articles were screened, of which 22 were included in the meta-analysis (k=28 samples, nAUT=113,227). The meta-analytic point prevalence of strabismus in autistic individuals was 13.4% (95% CrI [8.3,19.4]), and sensitivity analysis produced a very similar estimate (14.0% [7.0,22.0], nAUT=581). Esotropia was the predominant subtype of strabismus reported, accounting for approximately 55% of cases. Reported prevalence rates were higher in younger samples (BF10=13.43, R2Het =0.273) and samples recruited from optometry/ophthalmology clinics (BF10=11.47, R2Het =0.238). ConclusionThis meta-analysis found a high prevalence of strabismus in autistic individuals, with rates 3-10 times that of the general population. As untreated strabismus is a major risk factor for amblyopia in young children, these findings underscore the importance of timely screening and assessment of ocular problems in persons on the autism spectrum. Whats Known on This SubjectStrabismus has been reported to be more prevalent in individuals on the autism spectrum, but estimates have been very imprecise, ranging from 3-84% across studies. What This Study AddsThis study performs the first quantitative synthesis of strabismus prevalence in over 100,000 autistic individuals, generating more precise estimates of the prevalence of strabismus in the autistic population. Factors contributing to the large differences between studies are also examined using meta-regression.