Purpose
An increased prevalence of refractive error and increased astigmatism has been reported in Autistic Spectrum Disorder (ASD) (Haider et al. 2012). The present study investigated refractive error and corneal keratometry in children with ASD.
Methods
89 ASD participants (73 males) aged between 5-16 years, (mean age 10.7+/-3.2 years) were recruited through a population-based register and special educational schools. Age-matched controls were recruited from mainstream schools (n=204). Refractive error and corneal keratometry were measured using the Shin Nippon NVision-K 5001 auto-refractor 30 minutes after instillation of cyclopentolate HCl 1%. Where participants were not able to cooperate for auto-refraction (AR), retinoscopy was performed. Refractive errors and corneal powers were transformed into their M, J0 and J45 vector components for analysis (Thibos et al. 1997).
Results
ASD Success rates: Cycloplegic AR was measured in n=74 children (83%), n=9 non-cycloplegic AR (10%) and n=5 cycloplegic retinoscopy (6%). One participant did not cooperate for refractive error measurement. Corneal keratometry was successful for n=63 (71%). Control success rates: Cycloplegic AR n=203 (99.5%). Corneal keratometry was successful on 186 controls (92%). Table 1 includes summary statistics of the ASD and control data. No significant difference in J0 data was found for right and left eyes, so right eye data is presented. Mean refractive and corneal astigmatism was significantly higher in the ASD group than controls (one-way ANOVAs F(1,288)=22.6 and 24.1, p<0.00001). Refractive J0 indicated that 54% of the ASD group had with-the-rule astigmatism (44% controls), 29% against-the-rule (34% controls) and 18% no astigmatism (22% controls). In ASD, of those with refractive astigmatism >/=1.50D (n=9), 44% did not wear glasses. Refractive J0 was significantly greater in ASD than controls (one way ANOVA F(1,288)=3.99, p<0.05). No significant difference between ASD and controls was found for corneal J0 (one way ANOVA F(1,288)=0.55, p=0.46). The J45 component was small for both groups and no significant difference was found between ASD and controls.
Conclusions
This study confirms that refractive astigmatism is greater in ASD, and tends to be along the primary meridians; however this is not fully accounted for by the profile of corneal astigmatism.
Keywords: 676 refraction •
428 astigmatism •
479 cornea: clinical science