Visual findings in children with Autistic Spectrum Disorder

Abstract

 

Purpose

 

Anomalous visual findings have been described in Autistic Spectrum Disorder (ASD) including both superior and reduced visual acuity (VA) (Ashwin et al. 2009, Milne et al. 2009), an increased prevalence of strabismus (Denis et al. 1997) and reduced near point of convergence (NPC) (Milne et al. 2009). The aim of this study was to investigate visual findings in a large population of children with ASD.

 

Methods

 

Children with ASD (n=88, mean age 10.7 years ±3.1 years, range 5-16 years) were recruited from a regional population-based register (n=67) and special education schools (n=21). ASD diagnosis was available from the register and classified as; Autism (AU) n=50, Asperger’s syndrome (AS) n=33, unspecified n=5. Age-matched controls were recruited from mainstream schools (n=204, mean age 11.5 years ±3.1 years). Monocular recognition crowded VA, presence of strabismus, NPC, fusional reserves (FR) and Frisby stereoacuity scores were assessed.

 

Results

 

Table 1 presents success rates and summary statistics for all data. Controls demonstrated slightly but significantly better VA than the ASD group (Mann Whitney z=-2.49, p<0.05). A statistically significant higher prevalence of strabismus was noted for the ASD group (6.8%) [AU; 4%, AS; 12.1%] compared with the control group (1.4%) (Chi-squared χ²_{(2, 287)}=10.76, p<0.01). NPC was significantly poorer for AU subgroup compared to controls (Mann Whitney z=3.6, p<0.0005). There was no significant difference between ASD and control groups in magnitude of FR (Base out; Kruskal-Wallis=0.02, p=0.99, Base-in; Kruskal-Wallis=1.83, p=0.40). Analyses of stereoacuity scores identified that control and AS subgroups achieved significantly better stereoacuity compared to the AU group (Mann Whitney control; z=2.85 p<0.005, AS; z=3.22 p<0.005).

 

Conclusions

 

Children with ASD in the current study have a different visual profile when compared to controls; including increased prevalence of strabismus and reduced VA, NPC and stereoacuity. Whilst statistically significant, these differences in VA, NPC and stereoacuity may lack clinical relevance. However, clinicians should be aware of the increased prevalence of strabismus in this population.

 

 

Table 1; success rates and summary statistics for all data

 

Keywords: 722 strabismus • 754 visual acuity • 434 binocular vision/stereopsis