Children with vision problems, which are often easy to treat, are being misdiagnosed with ADHD and dyslexia.
Experts claim that, since Scotland's standard eye examination is designed to determine the health of the eye, a range of visual and perceptual problems can go undetected.
These difficulties can make it extremely challenging for children to learn how to read and behavioural problems, born out of frustration, can lead to misdiagnosis.
The Scottish Government is facing demands for a screening test that would focus on reading efficiency and identify problems such as eye movement control and focusing.
Children in Ayrshire struggling with reading already benefit from such a service.
"It is possible to come out of a standard eye test with 20:20 vision and still have difficulties with visual processing," explained Don Mackie of Learning and Teaching Scotland's communities team. "Some eye specialists are complaining because they are seeing kids being medicated for ADHD and discovering the cause of their behavioural problem was an undetected eye condition."
According to Mr Mackie, who was speaking at a national literacy conference in Glasgow last week, the fact that children with reading problems are likely to have difficulties with their vision is well known "in optometry circles", but not in teaching. "The knowledge does not seem to have transferred," he said.
Nadia Northway, an orthoptist and senior lecturer at Glasgow Caledonian University, would like teachers to be trained to identify potential problems and for screening to be available. "Diabetics have their feet screened. Why? Because we know they are more likely to have problems," she said." Similarly, if a child is struggling to read we know they are more likely to have visual problems that might not be detected in a routine eye test."
Recent research carried out by Dr Northway, and soon to be published, found that, of 108 adults with literacy difficulties, 107 required treatment for one or more problems with vision or visual processing.
"These problems can be treated, once detected," Mr Mackie said. "But that's the hard bit. When I work with people with reading difficulties, the first step is to get a proper eye check. It used to be to check for dyslexia, but that can't be cured."
A Scottish Government spokesperson said: "Our document, Health for all Children, recommends that all children should receive orthoptist screening in their pre-school year. NHS boards are in the process of implementing the recommendation."
WHAT TO LOOK FOR
- Does the pupil squint at text or cover one eye when reading?
- Does the learner give up or lose concentration after working for a short period?
- Do learners lose the place or miss words when readingskip lineshave difficulty finding words on the page?
WHAT TO ASK
- How does the writing look on the page?
- How close do you need to have the text when you are reading?
- Is the writing clear? Does it move on the page?
- How do your eyes feel after reading to the end of the page?
Binocular vision anomalies: binocular vision co-ordinates the eyes, resulting in a clear single image and is essential for comfortable reading.
Convergence: to focus on objects closer than 6m, the eyes need to rotate inwards or converge. Normal reading distance is 35cm, so those with convergence insufficiency will tire easily or will be unable to achieve a clear image.
Saccades: in reading, the eyes do not move continuously along a line of text but make short rapid movements (saccades), interspersed with short fixations. If saccades are poorly controlled, then the reader may lose his or her place or miss words out.
Visual sequential memory: the ability to recall accurately sequences of shapes and the order of letters after brief exposure. Difficulties with visual sequential memory will cause spelling and copying difficulties.