Kids with vision problems may have increased ADHD risk

Children with vision problems that are not correctable with glasses or contact lenses may be at twice the risk of developing attention deficit/hyperactivity disorder (ADHD), a new study has found.
Researchers from the University of Alabama in the US analysed data on more than 75,000 children (aged 4 to 17) from the 2011-12 National Survey of Children's Health.
Parents were asked whether they had ever been told their child had some type of vision problem that was not correctable with standard glasses or contact lenses.
They were also asked whether their child had any of 13 common chronic conditions of childhood, including ADHD.

Prevalence of ADHD was compared for children with or without vision problems, with adjustment for other factors.
Vision problems not correctable with glasses or contact lenses were reported for about 1.5 per cent of children, researchers said.

Examples of such conditions include disorders of eye alignment or eye movement, such as strabismus or nystagmus.
A current diagnosis of ADHD was reported for 15.6 per cent of children with vision problems, compared to 8.3 per cent of those without vision problems, researchers said.
Children with vision problems not correctable by glasses or contact lenses accounted for an estimated 2.7 per cent of children with current ADHD, they said.

After adjustment for factors known to be associated with ADHD, children with vision problems were 1.8 times more likely to have a current diagnosis of ADHD, researchers said.
For children with moderate vision problems, the odds were even greater - 2.6 times higher than in children without vision problems, they said.
There was no significant increase in ADHD for children with severe vision problems - likely reflecting the small numbers in this group, researchers said.
ADHD is a common neurodevelopmental disorder. Previous studies have raised concerns about ADHD in children with vision impairment.
The new findings add evidence that children with vision problems not correctable by glasses or contact lenses have a higher prevalence of ADHD, researchers said.

The association is independent of differences in patient and family characteristics, they said.
"It is likely that some children with vision problems are incorrectly identified as having ADHD," said Dawn K DeCarlo from University of Alabama.
Difficulty seeing may make it difficult for children to pay attention or to finish schoolwork in a timely manner.
Researchers also suggest that vision problems may take up more of children's "executive function" - higher-order cognitive processes used to plan, organise, pay attention, and manage time and space.
The findings will be published in the journal Optometry and Vision Science.