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Julie-Anne Little, Pamela Anketell, Lesley Doyle, Kathryn J Saunders; Exploring Accommodative accuracy in Autism Spectrum Disorder. Invest. Ophthalmol. Vis. Sci. 2014;55(13):3769.
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Atypical visual processing has been reported in autism spectrum disorder (ASD) (see Dakin and Frith 2005 for review), however no data exist exploring accommodative function in this patient group.
Accommodation and vergence were assessed using an infrared photorefraction system (PowerRefractor III) in a sub-group of children with ASD who had participated in a clinical study of vision (Anketell et al. 2013). The 29 participants (13.2+/-3 years) had good visual acuity (mean -0.16logMAR) and were highly compliant with previous testing. Participants viewed a naturalistic movie target at 5 dioptric demands under four viewing conditions: (i) full binocular, (ii) monocular, (iii) blurred binocular and (iv) blurred monocular. Blur was achieved with a Difference-of-Gaussian target. Individual lens and prism calibration protocols were conducted (Bharadwaj et al. 2013) and calibration applied to the data. The mean of two seconds of stable accommodative and vergence data for each target distance was captured and accommodative and vergence gain slopes and AC/A and CA/C ratios were calculated. Age-matched control children (12.3+/-3.3 years) underwent the same testing procedure. Following full optometric workup all wore appropriate refractive correction.
Accommodative gain slopes for the ASD group were significantly lower than those of controls for full binocular viewing (condition i) (ASD: 0.74+/-0.18; controls 0.87+/-0.22; one way ANOVA F(1,66)=6.78 p=0.01). There was no significant difference in accommodative gain between ASD and control data under the other conditions, however the loss of a disparity cue (condition ii) tended to affect accommodative accuracy more than the loss of a blur cue (condition iii). While seven ASD children (24%) had high AC/A or CA/C ratios outside the 95th centile derived from control data, overall there was no significant difference between CA/C and AC/A ratios found between groups. In both participant groups, those with lower accommodative gains had high AC/A ratios relative to their CA/C ratios (p<0.03).
In general, despite good visual function in the ASD group, accommodative responses were reduced, and there was evidence of anomalous coupling of accommodation and convergence.
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