Vision, Visual Processing Issues, and Dyslexia

You may have heard this common refrain before:

"Dyslexia is not a vision disorder"

Well, that depends on who you ask. 

We know from neuroscientist Maryanne Wolf's work that there are children who struggle to read but do NOT have phonological processing deficits (the stereotypical hallmark of what we often think of as “dyslexia”).

Leading language neuroscientist Stanislaus Deheane states there are visual subtypes of dyslexia, while another prominent reading scientist, Mark Seidenberg, has found that struggling readers have significantly higher difficulties with excluding visual distractions than normal readers. This can make passage-reading a major uphill battle. 

It’s a bit of a silly argument, really. 

Of course vision issues impact reading. This is why we buy reading glasses when we get older.  And of course issues with the brain’s visual processing system can impact reading. Reading is, in part, a visual processing act.

Whether or not we want to label reading problems caused by the visual processing system as part of  “dyslexia” is a separate question: one of many questions that challenge the utility of the current “dyslexia” label (see Elliot, 2020, O'Brien, Wolf & Lovett 2012, Mancarella 2025 )

But as parents and educators, we just want to get our kids reading. 

If our kids have a vision or visual processing disorder (also sometimes referred to as a visuo-attentional or visual attention processing deficit) that is impacting their reading, we need to do something about it, dyslexia label or no.

Keep in mind, however, that most struggling readers, even those with a visual processing deficit, will also need structured phonics and fluency interventions too.

Signs of vision issues or visual processing disorders:

• Slow, laborious reading
• Complaints that the words are fuzzy or moving
• Frequent headaches when reading for prolonged periods
• Feeling tired or rubbing eyes when reading for prolonged periods
  
• Turning the head to the side or closing one eye to read
  
• Swapping letters in words
• Skipping words in paragraphs or skipping letters at the beginnings or ends of words
• Inaccurate and/or strained passage-level reading, despite good reading at the word level
  
  
• Persistently low fluency despite solid phonics and phonemic awareness
• A child who is better at spelling than reading

Further Reading:   What is the Role of the Visual System in Reading & Dyslexia - International Dyslexia Association   || Visual Processing Disorders - National Center for Learning Disabilities ||

Vision Issues

If a child has issues with their eyesight, reading is going to remain a struggle. The trouble is, not all vision issues are picked up at an eye exam with a general practitioner.

One particularly common culprit that impacts reading and can occur even if a child has 20/20 vision is Convergence Insufficiency (CI). While there are self-screening tests you can do at home, you will want to contact an optometrist to diagnose (Note: optometrists and opthamologists do not necessarily include this as part of a standard eye exam, so be sure you ask). Convergence Insufficiency is 3x more common in children with ADHD compared to the general population (16% vs 2-3%). Eye exercises via "vision therapy" or prism glasses may be prescribed in order to correct the convergence insufficiency.

Visual Processing Deficits
Some children have issues not with vision per se, but with their brain’s visual or visuo-attentional processing system. In these cases, their brain has trouble processing visual information swiftly, keeping that information in order, and tuning out “noise” (surrounding letters). These issues, sometimes referred to as "tracking errors," often are more noticeable when reading passage-level text, rather than words in isolation. There are many, many different visual processing issues that can occur. Two common ones are letter position issues, and attentional issues, where a child’s brain accidentally swaps letters (see this example). Children with visual or visuo-attentional processing disorders may ... swap letters within words: reading FORM as FROM switch letters between words: reading PIKE BALE as PALE BIKE Some children may even pull letters from words on a different line up into the target word. In a block of text, letters from the next word, or from the line below might inadvertently be tacked onto or dropped into the target word. For example, in the following phrase, the two <s> might migrate so that the brain interprets:  “AS HE SAID”  as being:   “A SHE'S AID” If you notice your child making these sorts of errors when reading, they may have a visual processing deficit. A developmental optometrist should be able to diagnose this conclusively. Neuroscientist Stanislas Dehaene discusses some of these visual processing errors in this video at the 40 minute mark. Note: b / d confusion and reversing letters and words is not necessarily a sign of dyslexia or a visual processing disorder. The human brain is naturally designed to mentally rotate all visual objects as if they were 3D objects (watch this video from the 44 minute mark). A chair is a chair is a chair no matter which way you look at it. This is a natural brain process called mirror invariance and is something we ALL must train our brains to selectively turn off for letters, numbers, and words. Some of us are better at turning this off than others. An arrow or dot in the upper left of a page indicating where to start writing, as well as handwriting instruction should remediate these errors in time.

However, if these issues persistantly impact reading, even after handwriting intervention, you may want to consider a visual processing deficit. Vision and visuo-attentional processing issues don't necessarily impact kids’ ability to learn phonics, or to decode words in isolation. However, when they attempt to take those skills to the passage level, this is where the “visual noise” of the other surrounding letters will start to hurt their reading ability, and where their reading stamina and reading fluency can really drop off.

Visual Processing and Reading: The Chicken or the Egg?

Some get hung up on the question of whether or not visual processing issues are a cause of reading issues, or an effect of reading issues. This is really a moot argument because these two things are not mutually exclusive. A child can have visual processing issues that make it difficult to read, and reading can (and does!) improve the visual processing system. Reading, however, is not the only way to improve the visual processing system.

One of the ways that the visual processing system is trained IS via reading. When reading is remediated, the brain's visual processing system improves. For many students, you might consider a higher dose of the tried-and-true intervention for fluency issues: Repeated Reading.

In one study of a phonemic awareness and phonics intervention, researchers theorized that deficits in the visual processing system "may simply be the effect of less reading experience" (Olulade, 2013, Huettig 2020).

However, there are a few problems with this theory. First of all, there is a growing body of evidence that improving the visual processing system through non-reading-based intervention leads to improvements in reading (see, for example Pasqualotto et al 2025 | Valdois et al 2024 | Murray et al 2023 | Peters et al 2021 | Franseschini et al 2017 | Franseschini et al 2013 and the many articles linked at the end of this page). 

Second, visual processing difficulties can be BOTH a cause of reading struggles AND an effect of not having enough reading practice. These things are not mutually exclusive. 

The final problem is much more practical. While getting more reading practice certainly improves a child's visual processing system, and therefore improves their ability to read (the Matthew Effect), when reading is a gargantuan struggle, how do you get that child to read MORE? 

The debate on the specific causes-and-effects of various forms of dyslexia are likely to continue for some time. What we do know is that for many children, it is not purely a phonological deficit (see, for example O'Brien, Wolf & Lovett 2012). And in the meantime, we need practical advice. 

How do we help improve our kids' visual processing systems? 

And can we do this in ways other than reading intervention?

To answer these questions, we'll turn away from theory into the practical: visual processing intervention studies. 

Read More: Developmental Dyslexia Subtypes - O'Brien, Wolf, and Lovett 2012 ||

Visual Processing Diagnosis & Intervention

If you suspect that your child has a vision or visual processing disorder, you have a few options. For vision issues such as Convergence Insufficiency (CI), there are a few screening tests you can do at home. However, you’ll want to go to an optometrist or ophthalmologist to have it diagnosed definitively. Note that these types of vision issues are NOT part of a standard eye exam, and can occur in people who have 20/20 vision. You will need to specifically ask your eye doctor for these types of tests. Eye exercises or prism glasses may be prescribed in order to correct the convergence insufficiency. To diagnose visuo-attentional processing issues, you may need to see a developmental optometrist to definitively diagnose your child’s specific issue. As diagnosis and vision therapy can be pricey, you may opt to go with more affordable evidence-based interventions, as described later on in this post.

The typical prescription for children with visual processing or visuo-attentional issues is

"vision therapy"... which is a short way of saying paper or computer-based visual discrimination tasks or games. A WARNING ABOUT VISION THERAPY INTERVENTION:

Be careful whom you choose to diagnose your child.

The most often prescribed treatment for convergence insufficiency and visual processing disorder is “Vision Therapy.” Vision Therapy can be very costly, and your insurance may or may not cover it.

Many of those who offer diagnoses are ALSO vision therapists. There are many many tales of unscrupulous (or uninformed) providers who diagnose and prescribe vision therapy for patients who subesquently may or may not see reading benefits from it, costing parents thousands of dollars, with no tangible transfer to reading improvement.

Do your research. Join Facebook Groups such as Vision Therapy Parents Unite.

Find someone that you feel confident you can trust.

Or consider evidence-based affordable alternatives.

Affordable Alternatives to Vision Therapy Read the research on affordable alternatives to vision therapy.

You may find that you feel these are worth a try for your child.

Many modern vision therapy sessions are simply video games that are developed to stimulate and build the brain's visual processing system. There is a growing body of research that there are a number of affordable alternatives which can help with visual processing issues and reading fluency.

Reading Scaffolds

Low-cost alternatives include "scaffolds" or adjustments which help a student access passage-level text in a way that is easier for them to read, and therefore helps them get more reading practice (which as we saw above, will help with visual processing and reading fluency). These scaffolds include Finger Tracking; using Cardboard to Block Surrounding Words (in smaller-font situations, use a notched index card); increasing Letter and Word Spacing (see also this), Larger Font Size (there is some indication that this may help non-dyslexic readers too, but mixed results in other studies); and inserting Double Spacing for text reading.

Each of these simple scaffolds will help students who struggle to read letters in left-to-right order, and will also help tune out the "noise" of surrounding letters. As students get better and better at reading, these scaffolds should be gradually reduced until they are no longer needed anymore. As a sidenote, for kids with attentional issues, you may find that when they are tired, these issues will pop up again, and the scaffolds will once again help. These low-cost, easily accessible scaffolds are great for kids to have in their back pocket. Everyone has a finger for finger tracking and a sheet of paper they can notch for blocking off surrounding words. Some students will find that these accomodations or scaffolds are enough to get them the reading practice they need to read fluently. If not, or if progress is slow, they may need actual visual processing intervention.

Affordable Visual Processing Interventions

Paper-Based Visual Processing Interventions Some children may see benefits from using "search-and-find" or "maze" type paper-based visual processing interventions. See, for example: Visual Search Training. You can even grab a Where's Waldo book, and have the child trace their finger across the page in a left-to-right manner, searching for Waldo. Gamify this with a timing element to see how fast they can get through an entire page.

Computer & App-Based Visual Processing Interventions

More well researched are digital & gamified visual processing interventions, many of which can be done with freely available games. See, for example Visual Attention Span training and the use of specific, child friendly Action Video Games (AVGs), such as the free app Fruit Ninja, several Raving Rabbids Minigames, Plants vs Zombies 2, Nanostray 2, and Skies of Manawak. Multiple studies, including randomized controlled trials have supported the efficacy of these Action Video Games at improving reading accuracy and rate in both normal and dyslexic children, with some indication that computer-based interventions have larger effects for struggling readers in complex languages such as English (see Pasqualotto et al 2025). Click the embedded links to read the scientific studies.

Other AVG games have been found to lead to improvements in specific areas related to reading. For example playing 15 hours of Space Invaders Extreme 2 over the course of 1-2 months resulted in better ability to distinguish between words that differed by one phoneme, and the improvements remained at a six-month delayed post-test.

Be aware that children who score higher in the video games may see greater improvements in reading (see Bertoni et al 2021, Franceschini and Bertoni 2019).

I have personally seen incredible transformations in reading fluency after just 8 hours of "intervention" using these games, including Fruit Ninja, Zelda boss-battles, Mario Kart, and "Dash" games. In my experience, the fluency boost gained from these interventions is often enough to get children who have received or are receiving phonics intervention reading fluently enough that they begin to see themselves as readers. They see that they can read chapter books and enjoy them, likely for the first time in their lives. As a result, they read more, and as a result of more reading, they get better and better at reading, and there is a snowball effect.

That said, this is a newly emerging area of research, and it may or may not apply to your child's specific situation. You will need to judge whether you think these are sufficient or appropriate for your child.

And remember:

Remediating Visual Issues is NOT a substitute for Structured Literacy Intervention. Most struggling readers will need additional phonics and fluency interventions too.

Read More: What is the Role of the Visual System in Reading and Dyslexia? - IDA || Watch: Eyes on Reading with Emily Hanford and Stanislas Dehaene (watch from the 40 minute mark) Journal Articles: Characterizing Different Types of Developmental Dyslexias - Dehaene et al. 2023 PDF , PrePrint PDF || Multiple Types of Developmental Dyslexia - Friedmann 2024 || Multi-Factorial Nature of Reading Difficulties - Mancarella et al 2025 || Digital Tools for Reading Success - Meta-Analyses - Pasqualotto et al 2025 || Action Video Games: A Meta Analysis - Puccio et al 2024 || Effectiveness of Visual Attention Span Training - Valdois et al 2024 || Thinking Outside the Phonological Box - Murray & Birch 2023 || Action Video Game Training Improves Text Reading: an RCT - Peters et al 2021 || Action Video Games Improve Reading Abilities - Franceschini et al 2017 || Action Video Games Make Dyslexic Children Read Better - Franceschini et al 2013 ||