"All children with reading difficulties should be tested for convergence."
Other symptoms include getting sore eyes when reading, words moving or being blurry or appearing double. Or starting off reading OK, but then after a short while their reading gets worse. Convergence problems can exist with or without dyslexia, but all children with reading difficulties should be tested for it. Convergence is something that is easy to correct, and makes a massive difference to reading ability.
Learning to walk and talk are natural developmental milestones which don’t usually need to be taught. Pretty much all children develop these skills by themselves at the appropriate time. Learning to read is very different. It isn’t a natural developmental milestone, as our brains haven’t evolved to pick up reading. In fact, the part of the brain that fluent readers use to recognise words is actually the part of the brain designed to recognise faces!
Reading requires very good control of your eye muscles, which only develops as a result of learning to read. For example, a child who can only read English will be able to track left to right better than they can track right to left, whereas for a child who can only read Arabic the opposite will be true.
There are three main vision movements you make when reading: Saccades, Fixations and Convergence.
Saccades and Fixations are used for tracking your eyes across the page. Convergence is the ability focus both eyes on the same point or letter. When you read your eyes don’t flow smoothly across the page. They move in little jumps, called saccades. The points the jumps end on are called fixations. So we actually look at one letter then jump to another letter and read that. While focussing on one letter we can see four to eight letters either side of it.
Fluent readers jump every eight to 16 letters while reading. They normally jump from the middle of one word to the middle of the next. But if the word is long or hard or unexpected they may then jump backwards to an earlier point in the word and have another look at it.
Beginner and non-fluent readers make much smaller jumps, and more often jump backwards to have another look. But for children with dyslexia this is amplified hugely. A fluent child might focus on 150 points in a minute, with 50 of them being backwards jumps. But a typical dyslexic reader might focus on 1,000 points in a minute, with 500 of them being backwards – in fact some of the points won’t even be on the correct line!
Typically dyslexic children can’t control their eye muscles precisely enough to scan across the page correctly. This is one of the reasons they find it hard to understand what they’ve read. All of their brain processing power is spent processing the 1,000 points they’re looking at, and filtering out most of the 500 points they shouldn’t be looking at. This is also why they confuse ‘b’ and ‘d’. As their eyes are moving left to right as often as they’re moving right to left, the two letters look the same.
The other vision skill needed to read is the ability to converge (focus) both eyes on the same letter. If you can’t do this your brain will be receiving two different images. For example, when trying to read the word “brain”, one eye will be focussing on the ‘r’ and the other eye will be focussing on the ‘i’, which is very confusing.
"Dyslexic children can’t control their eye muscles precisely enough to scan across the page correctly."
This causes many typical dyslexic symptoms: words may appear to move, because the brain processes the r, then the i, without the eyes moving. If the words don’t appear to move, it’ll still make reading very tiring and slow, as the brain has to ignore all the images from one eye.
Specialised eye tests on 3 year olds, before they’ve even started school, can pick up with which children have eye tracking and convergence problems. Researchers (Levinson, 1994) have found a 95% correlation between children with eye tracking problems at three, and children who later have reading problems or dyslexia.
If children, particularly those with dyslexia, don’t develop good convergence and eye tracking skills naturally then it is something that should be practised at school via an intervention. Otherwise, they are likely to always struggle with reading, with spelling, and with copying off the board. Reading will forever be harder for them then it should be. A chore, not something they can enjoy.
Spelling requires even better vision skills than reading, as in order to for a word to be spelled correctly you have to get every letter in the right order, whereas for reading you can often look at the first few letters and guess without having to look at every single letter in the word.
If pupils aren’t able to focus on the letters in a word when they read, their spelling is likely to always be a bit hit and miss. And the often prescribed advice for poor spellers to ‘read more’ won’t help.
For further reading, I’d recommend Eye Movements in Dyslexia: Their Diagnostic Significance by George Th. Pavlidis.
Have you had experience teaching such readers? Share your tips below.