Visual Stress & Colour Overlays
Visual Stress and Colour Overlays — What the Evidence Says
Some people report visual discomfort while reading: glare, headaches, blurred or moving-looking text, or difficulty keeping their place. “Visual stress” is often used as a broad description. “Irlen Syndrome” is a more specific proposed explanation, but its definition, assessment and treatment evidence remain disputed.
A coloured overlay may make a page feel more comfortable for some readers, while making no difference for others. Research does not support presenting overlays as a treatment for dyslexia, and the evidence for visual-stress benefits is limited and inconsistent. A free, reversible screen tint is best treated as a personal display preference.
Persistent blur, headaches, eye strain or light sensitivity deserve a sight test or clinical advice, because an overlay cannot identify the cause.
Symptoms People Describe as Visual Stress
People use the term visual stress for experiences such as:
- •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
These symptoms are not specific to Irlen Syndrome and do not diagnose dyslexia. Start with a routine sight test, particularly when symptoms are new, persistent or painful.
Which Colour Overlay Works Best?
There is no clinically proven best colour. If you want to test a tint, compare the same passage with and without it while keeping the font, size and spacing unchanged. Use a pale colour that preserves strong contrast, and stop if it makes reading less comfortable.
Yellow
A pale warm tint to compare with the original white page.
Blue
A pale cool tint. Keep opacity low enough to preserve text contrast.
Green
Another light option to test without changing the font or spacing.
Pink / Rose
A soft warm option for readers who prefer it to yellow.
Lavender
A muted cool option that can be compared with blue.
Custom
Dyslexly lets you set any colour and opacity — because the right tint is personal.
Using Colour Overlays on Websites
Physical coloured overlays are tinted sheets placed over print. Some operating systems and reading apps offer background colours, but many ordinary web pages do not expose that setting.
Dyslexly adds an adjustable tint to most compatible websites in Chrome. You choose the colour and opacity, compare it with the original page, and can remove it immediately.
The overlay control is free and saves your preference. It is not equivalent to a clinical assessment or prescribed lens, and it does not diagnose or treat dyslexia.
For more detail, read our evidence-led background colour guide, the College of Optometrists guidance, and the NHS evidence review.
Try Dyslexly Free
Colour overlays, four font choices, line focus and read-aloud on most compatible websites. Free to install, with no account needed for the reading tools.
Frequently Asked Questions
What is Irlen Syndrome?⌄
Irlen Syndrome is one name used for a proposed explanation of visual discomfort or distortion while reading. The terms, diagnostic criteria and evidence remain debated. Symptoms such as glare, headaches, blur or losing your place can have other causes, so persistent symptoms should be discussed with an eye-care professional.
Do colour overlays actually help Irlen Syndrome?⌄
Evidence is limited and inconsistent. Some people report that a particular tint makes a page more comfortable, but overlays have not been shown to treat dyslexia and they do not help everyone. Dyslexly provides a free preference setting so you can compare tinted and untinted pages without buying lenses.
Is Irlen Syndrome the same as dyslexia?⌄
No. Dyslexia primarily affects accurate and fluent word reading and spelling; it is not caused or treated by changing colour. A person with or without dyslexia may also experience visual discomfort. An overlay can be tried as a comfort preference, not as a dyslexia assessment or treatment.
Can I use a colour overlay on any website?⌄
Dyslexly can tint most ordinary web pages in Chrome and other Chromium browsers. Browser settings pages, the Chrome Web Store, some protected frames and scanned documents are restricted. You can change the colour and opacity or turn the overlay off at any time.
How is this different from physical Irlen overlays?⌄
A physical overlay is a tinted sheet placed over print. Dyslexly adds a visual tint to compatible web pages and lets you adjust or remove it instantly. It is a free display preference, not a prescribed filter, diagnosis or medical treatment.