Reductions in vision correlate with lower literacy scores on standardised tests, a new study showed.
“This study strengthens the argument for a national vision screening programme,” wrote Alison Bruce, Bradford Institute for Health Research in Bradford, United Kingdom, and her colleagues in the British Medical Journal Open
While the U.K. National Screening Committee recommends vision screening at age 4 to 5 years, few studies have examined the correlation of vision levels of children to educational achievement.
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To explore this association, Bruce and her colleagues analysed data from the Born in Bradford birth cohort study, which collected epidemiological data during pregnancy and birth, and literacy measures in a subgroup of the children during their first year in school. In addition, Bradford has a comprehensive vision screening programme.
From 2007 to 2010, researchers recruited 12,453 women who were waiting for a glucose tolerance test routinely offered to all pregnant women registered at the Bradford Royal Infirmary at 26 to 28 weeks gestation.
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Separately, researchers invited all 123 Bradford primary schools to participate in a literacy screening. Of them, 76 agreed, leading to the participation of 2,929 children from 2012 to 2014.
The screening included letter identification on the Woodcock Reading Mastery Tests-Revised subtest, and vocabulary measurement on the British Picture Vocabulary Scale.
The researchers correlated this data with results from a vision screening programme conducted in Bradford schools by orthoptists that reaches 97% of Bradford school children.
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As a result, the researchers were able to cross reference vision and literacy data on 5,836 children.
The researchers calculated the overall mean visual acuity (VA) for all children who received the vision screening was 0.14 logMAR. They found 8.7% had a VA worse than 0.2 logMAR, 4% worse than 0.31 logMAR, and 1.8% worse than 0.4 logMAR.
Poverty, ethnic diversity
Bradford has high levels of poverty and ethnic diversity. About half the births in the city are to women of South Asian origin.
In this study, 5.2% of children identified by the researchers as “Pakistani” had a VA worse than 0.3 logMar compared with 2.7% of children identified as “white British” and 2.8% of children identified as “other ethnicities.” The differences were not statistically significant.
Likewise, there was no statistical difference in literacy between the “white British” and “Pakistani” children.
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These findings showed the Bradford children have a higher prevalence of poor presenting VA than reports of similar cohorts. The researchers estimated 2% of the children in their study could be classified as visually impaired.
Two percent of the children in this study were wearing glasses at vision screening, a rate similar to the one found in a study of children in the United States, but lower than the 6% found in a study in Australia.
“The high levels of deprivation in the city may help explain the higher prevalence level of poor [VA],” the researchers wrote.
The participants’ mean literacy score was 107.07. An unadjusted analysis showed they scored 2.42 points lower in literacy for every 1 line (0.10 logMAR) of reduced VA. The researchers adjusted for vocabulary, demographic factors and socioeconomic factors, and still found that the literacy score was reduced by 1.65 points for every line.
Adjustment for mean spherical equivalent, on the other hand, was not associated with literacy.
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This was the first study to “reliably demonstrate that poor [VA] in young children is associated with reduced early developing literacy,” the researchers wrote.
A few other studies have looked into similar questions, they acknowledge. In the United States, one study found no effect of VA on academic performance, but the key indicator of academic performance was not available for a large proportion of the children, necessitating reliance on a proxy measure, and the study did not control for confounding variables.
Likewise, a retrospective analysis of the 1,958 British birth cohort reporting outcomes at age 11 years found no association between unilateral amblyopia and educational, health or social outcomes. However, the study excluded participants with bilateral vision loss.
National Eye Health Week
National Eye Health Week, an awareness campaign supported by several companies providing optical services, pointed to the study as evidence for the importance of screening.
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“As a child’s eyesight is usually fully developed by the age of eight, regular sight tests, every two years unless advised otherwise by your optometrist, are crucial,” said David Cartwright, chairman, National Eye Health Week, in a prepared statement.
If detected early, amblyopia and squint can often be corrected and other visual problems such as childhood myopia can be managed effectively, yet, 50% of parents with children age eight and under have never taken their child for a sight test, he said.
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Over the past years, levels of myopia have more than doubled in the United Kingdom and now affect about 1 in 5 U.K. teenagers, according to the press release.