An under-diagnosed eye problem could be the cause of your child's temper tantrums and difficulty concentrating in class, says an Edmonton optometrist.

The problem starts when the eyes aren't working together as a team, says optometrist Jacinta Yeung.

"If the eyes aren't working together, they can be bringing in different pieces of information and then the brain has to sort through two different pieces of information."

Kim Knull, a registered psychologist and mother of a 6-year-old girl with the condition, says her daughter's problem first became evident when she entered Kindergarten.

Kim Knull

Psychologist and mother-of-two, Kim Knull says a vision problem left her normally happy and easy-going daughter exhausted and prone to temper tantrums. (Kim Knull/Facebook)

"She'd come home really tired, even though it was a half a day … then in Grade One, she started to have some problems with her piano lessons — she wasn't keeping up with other kids — and the same with reading. She didn't seem to be progressing as well as the other children."

At first, it looked like a behaviour problem, said Knull, a former teacher.

"But the other thing that we noticed was — especially the first two months of Grade One — she was coming home and having temper tantrums."

For Knull, seeing her usually-happy and compliant daughter exhausted and frustrated was a red flag.

"That was not her style of communicating," said Knull. "She's not a temper tantrum kid."

Around the same time, Knull began to notice her daughter was not able to complete her eye exams at the doctor's office — always failing when it came to the final line. At first, Knull thought it was a matter of learning the letters, but as her daughter moved into Grade Two, she realized that wasn't the case.

"By this year, she's reading, so when she wasn't able to do the line of letters, the optometrist … said 'why don't you get her vision assessed?'"

Knull balked at first, since her daughter had 20/20 vision — but as she later learned, there is a lot more to vision than seeing things clearly.

Eyes working independently lead to confusion

"Being able to see 20/20 is a very important part of vision but that's not the only skill," says Yeung.

"If you think about driving, you have to assess where all the cars are around you, you have to assess the speed you're going, how fast the other cars are going, depth perception — all that stuff is all related."

Most children learn basic vision — which Yeung differentiates from sight — as babies, crawling and reaching for objects.

However, some children have a vision problem that causes a disconnect between what's on the page and how it's interpreted by the brain, she said. As a result, words may appear to double, disappear or dance in front of their eyes.

The brain then ends up spending more time trying to sort out the conflicting data at the expense of comprehending what's actually going on in front of them.

This can be a major problem in the classroom where up to 80 per cent of learning is visual, said Yeung, and lead to eye fatigue which can send a child looking for distraction. As a result, the condition is sometimes mistaken for Attention Deficit Hyperactivity Disorder.

Up to one in four children have a vision problem unrelated to simple sight, she said.

"The biggest thing is that the kids don't know that this isn't a normal way of seeing, because they've only seen this way," Yeung said.

'I couldn't believe the transformation'

To find out how their children see the world, Yeung says parents should ask specific questions: 'Are you seeing double? Are the letters and words moving on the page? Are things blurry around the edges?'

Parents should also be on the lookout for red eyes and frequent headaches, she added. Likewise, be aware of how often your child rubs his or her eyes after looking closely at something, covers an eye, or tilts a page from side to side while reading.

Once diagnosed, the problem can be treated using vision therapy — a weekly activity session designed to teach children how to use their vision more efficiently.

"We work on eye-teaming skills, tracking, even processing and perceptual things, so we play a lot of games and puzzles," she said. Those games can include jumping on a trampoline, throwing balls, tracking moving objects with their eyes.

While anyone can benefit from practising their vision skills, the change can be dramatic among children who previously had problems relaying messages from their eyes to brain.

"Part of my feeling terrible as a parent is that I had no idea how much this was impacting her until it started to get better," said Knull of watching her own daughter's recovery.

"I couldn't believe the transformation."

Since beginning vision training, Knull says her daughter's reading fluency and compliance have both improved, as has her mood.

"If I could have projected five or ten years out, I [used] to see her being one of those children who hated school, who would not want to go on to university because school was just so much work — but now, she's got so much confidence … and she actually feels like she's a smart kid."

The Alberta Association of Optometrists recommends children get an eye exam every year — even if they don't appear to have any vision problems.

Alberta Health covers the cost of annual eye exams for children and teens up to the age of 19.