Visual Stress & Colour Overlays
Irlen Syndrome — What It Is and How Colour Overlays Help
Irlen Syndrome — also called Meares-Irlen Syndrome or visual stress — is a perceptual processing difficulty that makes reading from screens and printed pages genuinely painful for millions of people. Unlike dyslexia, it is not primarily a language processing issue. The problem is visual: the brain struggles to process certain wavelengths of light, causing text to appear to move, blur, or shimmer.
The most effective intervention for Irlen Syndrome is surprisingly simple: a coloured overlay. By tinting the page, you reduce the high contrast between dark text and bright white backgrounds — the specific combination that triggers perceptual disturbances in most sufferers. The right colour varies from person to person, which is why self-testing matters more than following a prescribed tint.
Symptoms of Irlen Syndrome
Irlen Syndrome presents differently in different people. Common symptoms include:
- •Words appearing to move, shake, blur, or merge while reading
- •Headaches or eye strain during or after reading
- •Difficulty reading for sustained periods
- •Losing your place on a line or skipping lines
- •Sensitivity to bright lights, glare, or fluorescent lighting
- •Letters or words appearing to swap, reverse, or jump
- •Fatigue that seems out of proportion to the reading workload
Many people with Irlen Syndrome were previously told they had poor concentration, were not trying hard enough at school, or had weak eyesight — despite passing standard eye tests. The condition is not detected by routine vision screening because the eyes themselves function normally.
Which Colour Overlay Works Best?
There is no universal answer — the right colour is highly individual. The overlays below are the most commonly reported as helpful, but the only way to know what works for you is to try them. Dyslexly lets you switch instantly between colours on any website.
Yellow
Most commonly reported as helpful. Reduces blue light contrast and softens bright white backgrounds.
Blue
Preferred by some for reducing the glare of high-contrast text on white.
Green
Works well for readers who experience words appearing to ripple or move.
Pink / Rose
Often effective for readers with strong light sensitivity and photophobia.
Lavender
A gentler alternative to blue — useful for evening reading.
Custom
Dyslexly lets you set any colour and opacity — because the right tint is personal.
Using Colour Overlays on Websites
Physical coloured overlays — plastic sheets placed over printed pages — have been used in classrooms for decades. But most reading now happens on screens, and the web has no built-in support for colour overlays.
Dyslexly solves this with a full-page colour overlay that works on any website in Chrome. You choose the colour and opacity, and the overlay applies immediately — to Google, Wikipedia, news sites, email, educational platforms, or anywhere else you read online.
Unlike physical overlays, it is adjustable in real time, saves your preference, and costs nothing. You do not need a formal Irlen assessment or a prescription tint to use it.
Try Dyslexly Free
Colour overlays, OpenDyslexic font, line focus, and word-by-word read-aloud — on every website you visit. Free to install, no account needed.
Frequently Asked Questions
What is Irlen Syndrome?⌄
Irlen Syndrome (also called Meares-Irlen Syndrome or visual stress) is a perceptual processing disorder that makes reading difficult. Sufferers often experience words appearing to move, blur or shimmer on the page, headaches when reading, and light sensitivity. It is not a problem with eyesight — the eyes themselves work normally — but with how the brain processes visual information.
Do colour overlays actually help Irlen Syndrome?⌄
For many people, yes. Coloured overlays reduce the visual contrast that triggers perceptual disturbances. The specific colour that helps varies by individual — yellow, blue, green and pink are common, but the right tint is personal. Dyslexly lets you try any colour in real time on websites so you can find what works for you.
Is Irlen Syndrome the same as dyslexia?⌄
No — they are different conditions that often co-occur. Dyslexia is primarily a language processing difficulty affecting reading and writing. Irlen Syndrome is a visual processing difficulty. Someone can have one, both or neither. The reading tools that help each condition overlap significantly, which is why Dyslexly addresses both.
Can I use a colour overlay on any website?⌄
Yes — that is exactly what Dyslexly does. It applies a colour overlay to the entire browser tab, regardless of what site you are on. You can set a default colour that applies everywhere, or change it per site. It works on Google, Wikipedia, news sites, email clients, educational platforms and anywhere else you read online.
How is this different from physical Irlen overlays?⌄
Physical overlays are plastic sheets you place over a printed page. Dyslexly is the digital equivalent — it tints your entire browser window. It works for any online reading, is free, adjustable in real time, and does not require a formal Irlen assessment to use. Many people use both: physical overlays for printed material and Dyslexly for screens.