Children's reading difficulties linked to vision problems not picked up during traditional tests

Reading challenges may be linked to problems with binocular vision.
Reading challenges may be linked to problems with binocular vision. Photo: Shutterstock

Children with reading difficulties may have problems with their eyesight that are not picked up via traditional tests, according to new research.

The study, published in the Journal of Optometryfound that children experiencing challenges with reading may have lower than expected binocular vision test results.

"A complete binocular vision assessment is not always part of the standard vision test," said lead researcher Dr. Lisa Christian. "However, binocular vision problems could be compounding a child's academic difficulties, and should be investigated." In fact, the authors note, "From an optometrist's perspective, a decrease in reading ability may be associated with poor visual acuity, unstable binocular vision, or ocular disease."

As part of the research, 121 students reading two or more levels below their expected grade, underwent vision and binocular testing. The team found that while over three quarters of the students had good eyesight, when it came to their binocular vision, more than a third of the children scored below what optometrists classify as normal.

But how does this impact their reading?

"Kids can see words on the page, but if (for example) they have difficulty turning their eyes in to read or focusing words on a page, they may experience symptoms of eye strain, double vision or fatigue after five or 10 minutes," Christian says, adding that it's not just about visual acuity but, "how well the eyes work together when performing an activity such as reading."

Binocular vision problems fall under three different categories: accommodation, vergence and oculomotor. Children experiencing accommodative issues may have problems changing focus from one distance to another, or sustaining clear focus of words or numbers up close. Vergence related issues cause problems for children by making it harder to turn their eye in or out. And oculomotor issues make eye-tracking hard for kids, meaning they may lose their place when trying to read.

Additionally, younger children may be unaware of their visual problems or are unable to describe their associated symptoms. "In these cases, observations from parents and teachers such as eye rubbing, close working distance, or avoidance of near work, provide additional information," the authors write.

And their recommendations are clear: "To thoroughly investigate the binocular vision system, we recommend that tests of accommodation, binocular vision, and oculomotor function should be performed on all children, especially those with identified reading problems."


Sophie Koh, optometrist advisor at Optometry Australia agrees. In fact, Optometry Australia recommends that all children should have a comprehensive eye examination before starting school and regularly throughout their school life as kids' eyes change rapidly during this period.

"Binocular vision is routinely tested for kids - and adults - by Australian optometrists during a comprehensive eye examination," Ms Koh says. "It is especially vital during a children's eye examination to check a child's binocular status because, as the research states, there is a relationship between binocular vision function and reading performance."

Ms Koh explains that while children may not present with a refractive error (no myopia, hyperopia or astigmatism), and can see clearly on a vision chart, they may still have a binocular vision issue that needs to be addressed.  "In some cases this may lead to them avoiding reading tasks and falling behind at school," she says. In fact, last year, Australian Research from the Queensland University of Technology highlighted a link between poor scores on NAPLAN tests of literacy and numeracy and poor vision.

According to Ms Koh, Parents should be on the lookout for any of these signs of vision problems:

  • Noticeable tilting or turning of the head when their child is looking at something
  • Frequent blinking or rubbing of the eyes
  • Red or watery eyes
  • Difficulty reading, such as skipping and confusing words, and holding a book very close while reading
  • Complaints of headaches and blurred or double vision
  • Squinting or having difficulty recognising things or people in the distance
  • One eye turning in or out while the other points straight ahead

If you notice any of these symptoms in your child, you should see an optometrist.

"Some patients may need follow-up appointments with their optometrist due to their binocular vision issues," Ms Koh adds, "as some of these 'problems' may be improved with simple exercises." This may involve using lenses, prisms and other equipment or tools at home or in supervised sessions in the optometry practice.

"It's also vital that the child's ocular health be determined (e.g. the optometrist will check the health of the eyes, looking at the eye tissues such as the retina)," says Ms Koh, "to exclude serious pathology issues before commencing binocular vision interventions."  

You can book a comprehensive eye exam with your local optometrist, using Optometry Australia's patient information site