A comparison of measures of reading and intelligence as risk factors for the development of myopia in a UK cohort of children.

AIM: Evidence suggests that reading may be an important risk factor for myopia, but recent reports find that performance in non-verbal intelligence tests may be more important or that near-work is not associated with myopia.
METHODS: Non-cycloplegic autorefraction data were available at the ages of 7 and 10 years from a birth cohort study. Children whose right eye spherical equivalent autorefraction was <or=-1.50 D were categorised as "likely to be myopic." The authors tested associations between school-based Standardised Assesment Tests (SATS) for reading and mathematics, maternal report of child liking reading, the Wescher Objective Reading Dimension (WORD) test results, verbal and non-verbal IQ, and the child being in the "likely to be myopic" group.
RESULTS: 6871 children (59.7% of remaining cohort) had refractive and risk factor data at 7, of whom 1.5% were in the "likely to be myopic" group. Predictors (odds ratios, OR: 95% CI) of concurrent (at 7) risk for myopia were good performance in the SATS reading (2.60:1.61, 4.19; p<0.001), SATS maths (1.90: 1.19, 3.05; p = 0.008), the WORD (2.72:1.60, 4.64; p = 0.001) and verbal IQ tests (1.99, 1.13, 3.52; p = 0.055) after adjustment for the number of myopic parents (p = 0.014) and ethnicity (p = 0.129). However, the strongest predictor of incident myopia developing between 7 and 10 years was the parental report of whether the child liked reading: (4.05:1.27, 12.89; p = 0.031), adjusted for parental myopia (p = 0.033) and ethnicity (p = 0.008).
CONCLUSIONS: Factors associated with reading may play a part in myopia development. Further comparisons of different measures of reading-related activity or verbal ability may help clarify which of the related behavioural characteristics are causally related to myopia prevalence.