Abstract
Purpose. Autism spectrum disorder (ASD) is an increasingly diagnosed neurodevelopmental disorder, with an incidence in children now greater than 1%. Surprisingly, given the assumption that ASD impacts the processing of visual stimuli, systematic studies of even basic visual functioning have yet to be conducted on this population, and the limited available reports are equivocal. Here we conduct the first comprehensive study of the development of spatial vision and refractive status in this population. Methods. 44 children and young adults (age range: 3-22 years) with a primary diagnosis of ASD were tested with a battery of tests developed for an early childhood eye and vision screening program (Adams et al: VSS 07, 08). These included measures of visual acuity, alignment, stereoacuity, refractive error, contrast sensitivity (CS), and Vernier acuity. Children were tested monocularly and with optical correction if prescribed. Results. Children were very compliant with 95% completing all tests in both eyes. Compared to controls, 3-to- 6 year-olds (n =21) showed moderate deficits in visual acuity (M = 0.38 LogMAR; 20/48), CS (M= 53 CS units), Vernier acuity (M = 0.70 log min), stereoacuity (M = 2.28 log arcsec) and ocular alignment (31% failed). Older 7-22-year-olds (n = 23) performed even more poorly, showing significant deficits in visual acuity (20/94; 0.67 LogMAR), Vernier acuity (0.85 log min), stereoacuity (2.41 log arcsec) and ocular alignment (65% failed), but only a moderate deficit in CS (M = 56 CS units).Conversely, refractive error showed a relatively normal age distribution. Conclusions. Children with ASD are at risk for eye and visual dysfunction. However, given that most of these children had relatively normal levels of refractive error, the basis of their deficits appears to be within the central visual pathways and/or the visual cortex and is perhaps related to the neural origin of the disease.
Natural Sciences And Engineering Research Council of Canada/ Janeway Hospital Research Advisory Foundation.