Reduced accommodation in children with Autism Spectrum Disorder

Abstract

Purpose: Reduced accommodation has previously been described in children with cerebral palsy (McClelland et al. 2006) and Down syndrome (Woodhouse et al. 1993). However, clinical measures of accommodation have not been reported in children with autism spectrum disorder (ASD), although Milne et al. (2009) describe reduced near point of convergence in this group.

Methods: Accommodation was assessed for 128 children with ASD (Autism=88, Asperger Syndrome=40) (mean age 10.9±3.3years) recruited from a regional population-based register. A control group of 206 typically developing children (mean age 11.5±3.1years) were recruited from mainstream education. Amplitude of accommodation (AoA) was assessed subjectively using the push-up technique. Accommodative response (AR) was assessed objectively using the Modified Nott Dynamic retinoscopy technique for a 4D demand. Near visual acuity (NVA) was assessed using the Massachusetts Near Vision Test and near point of convergence (NPC) with the RAF rule. All participants underwent cycloplegic autorefraction. Children using a medication which may affect accommodation were excluded from analyses.

Results: AoA was recorded binocularly for 73 ASD and 206 control participants. The median binocular AoA was 19.2D (IQR 14-20) and 15.0D (IQR14-20) for the ASD and control groups respectively with no statistically significant difference between groups (z=-1.33 p=0.18). AR was successfully assessed from 124 ASD and 206 control participants. A lag of accommodation >1.08D for a 4D demand is defined as clinically significant (McClelland & Saunders 2004). Based on this classification three times more participants with ASD (15.7%) than controls (5.3%) had a significant lag (Pearson’s chi squared χ²=9.13, p=0.003). NVA for participants with ASD with a lag of accommodation was 0.00logMAR (IQR -0.04 to 0.10) which was significantly reduced compared to those without a lag (NVA= -0.06logMAR IQR -0.12 to 0.00)(z=-2.48 p=0.01). NPC measures were not significantly reduced for participants with ASD with a lag of accommodation (z=-1.15, p=0.25).

Conclusions: This is the first report of reduced accommodation in children with ASD; a deficit is associated with a slight but significant reduction in NVA. Clinicians should include an assessment of AR to ensure identification and appropriate clinical management in this population.

Keywords: 404 accommodation • 434 binocular vision/stereopsis • 756 visual development