(Part 2 of 3 in a blog series about vision and reading)
In the previous post, we talked about children who manage to read for about five minutes – and then lose focus. This is easily interpreted as a lack of concentration, immaturity, or disinterest in reading. But research shows that the explanation is often different, and it concerns something we rarely think about: vision.
Reading is fundamentally a visual process
We are used to thinking of reading as something phonetic and linguistic – decoding sounds and understanding words. But before the brain can take over and process the linguistic content, a complex visual process must function. All reading is based on visual impressions from the printed material, and if these impressions are unclear, unstable, or incorrectly coordinated, our entire reading ability is affected.
During reading, the eyes perform constant and precise muscular work. Six muscles in each eye collaborate to move the gaze in fast, accurate jumps along the line – so-called saccades. At the same time, the lens in the eye must adjust (accommodate) to see the text sharply at close range, and both eyes must actively turn inward and point at exactly the same spot (converge). If any of this fails, the text looks blurry, seems to jump around, or appears as a double image.
Research shows that as many as 20–40 percent of all students in school have difficulties with accommodation, convergence, or other binocular functions (Borsting et al., 2003; Heim, 2004; Wilhelmsen, 2012). Most of these students are not even aware of it – they have never experienced anything else and have nothing to compare it with.
Near vision is not the same as distance vision
There is an important point that is often overlooked: a child can have acceptable vision in the eye test conducted by the school nurse – and still have great difficulty seeing clearly at reading distance. This is because standard eye tests measure visual acuity at a distance (3–6 meters), while reading requires a completely different visual capacity at 40 cm.
In a study of newly enrolled six-year-olds, researcher Gunvor B. Wilhelmsen (2016) found that the children's near visual acuity was, on average, 20 percent lower than their distance visual acuity.
None of the children were aware that they saw worse at close range, and standard screening had not identified the problem. Furthermore, girls' near vision was significantly better than boys', a gender difference that may help explain why boys more often experience difficulties in the early years of literacy acquisition.
What happens in the classroom when visual functions are not adequate?
Imagine a student who, with every new sentence, has to struggle to keep the text sharp and stable. Their eye muscles tire. The letters start to move, jump, or blur. The student can persist – perhaps for five minutes – but then their energy runs out. The book is put aside, their gaze wanders, conversation with a neighbor begins. It looks like disinterest or a lack of focus, but the cause is visual fatigue.
Anna (fictitious name) was eleven years old and in 6th grade when she underwent a structured vision intervention led by a vision teacher. Her near visual acuity was borderline for visual impairment according to WHO's definition, she had weak convergence, and her eyes ached. Neither she, her parents, nor her teachers had connected these problems with her reading difficulties – they had no reason to suspect a connection.
After eleven weeks of targeted eye muscle exercises – without specifically training reading – Anna's reading speed increased from 119 to 170 words per minute, an improvement of 43 percent. Her near visual acuity dramatically improved, and she reported that the letters had stopped jumping around. "Now I can even see clearly from the back of the classroom. Before, I was always so tired and my eyes were lazy and sore," she said after the intervention.
What can you, as a teacher, look for?
Vision-related reading problems are rarely obvious. There are no visible signs like glasses or a crooked gaze – and the student doesn't know that their vision differs from others'. But there are signals to watch out for.
You might observe that the student:
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Sits very close to the screen or book
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Holds their head at an unusual angle – often bent down with gaze directed upwards
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Rubs their eyes or blinks a lot
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Reads slowly without a clear cognitive explanation
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Loses their place in the text and needs to follow along with their finger
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Avoids tasks that require near vision or gives up unusually quickly
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Copies from a neighbor rather than from the board
The student might complain of:
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Eye pain, especially when reading
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Blurry or double text – "the letters are dancing"
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Headache or neck pain after reading
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Finding reading boring (which can be a strategy to avoid effort)
These signals don't always point to vision problems, but they always warrant considering whether to train one's vision with the help of, for example, Imvi.
What you can read in the next part...
We now know that reading begins as a visual process and that many students struggle with precisely the visual functions that are crucial for reading to work. But what can schools actually do with that knowledge?
In the third and final post in this series, we look at how visual pedagogy works in practice, which interventions are effective – and what this means for how we think about reading development and reading difficulties in schools.
