The prevalence of specific reading disability in an amblyopic population. A preliminary report.

Purpose: To investigate the prevalence of specific reading disability in children with functional amblyopia and to explore the relationship between the two.

Methods: In this prospective study, 20 consecutive children, aged 6 to 15 years (mean 8 +/-1.99 years), and diagnosed with amblyopia underwent a vision and reading assessment. The orthoptic examination included the assessment of participants' visual acuity, ocular motility and binocular functions. Specific reading disability was diagnosed using the Wide Range Achievement Test (WRAT III Reading Subtest). Intelligence, phonological awareness, rapid automatized naming (RAN), and the ability to read pseudo or nonsense words was also assessed using various psycho-linguistic reading tests.

Results: The prevalence of specific reading disability in this small series of amblyopic children was found to be 5% (n=1/20). This was even less than that reported in the local Victoria general population (16%). The type of amblyopia appeared related to phonological awareness (p=0.018) and decoding words (p=0.024), those with anisometropic amblyopia performing significantly better on these tasks than the strabismic amblyopes. The presence of binocular vision functions was also related to decoding words; those with binocular single vision performed better than those with suppression and lacking single binocular vision (p=0.007). Generally, amblyopic children also showed a lower RAN score when compared to phonological awareness score. There was no statistically significant difference for the severity of amblyopia (p=>0.05).

Conclusions: In this very small pilot series, reading disorders were relatively rare in children with amblyopia. However, strabismic amblyopia and presence of suppression may have an adverse effect on phonological skills. In addition, amblyopia may be associated with a deficit in RAN. Further research is needed and planned to gain a better understanding about the relationship between amblyopia and reading ability.