Learn About Colour Blindness
Evidence-based guides on colour vision deficiency — for patients, parents, designers, and developers.
Can Colour Vision Change Later in Life?
Why new or worsening colour-vision changes need professional assessment, and what to watch for.
How to Use an Online Colour Vision Test
Prepare for a browser-based screen, understand the limits, and know when to seek formal testing.
Make Charts Accessible for Colour Blindness
A practical checklist for labels, patterns, contrast, tables, and colour-independent data graphics.
What is Colour Blindness?
Causes, symptoms, statistics, and everything you need to know about colour vision deficiency.
Types of Colour Blindness
A complete breakdown of protanopia, deuteranopia, tritanopia, and achromatopsia.
Protanopia Explained
What protanopia is, how it affects vision, how it is inherited, and how it is diagnosed.
Deuteranopia Explained
The most common form of colour blindness — what deuteranopia is and how it differs from protanopia.
Tritanopia Explained
The rare blue-yellow form of colour blindness — causes, symptoms, and diagnosis.
Colour Blindness in Children
How to identify colour blindness in kids, when to test, and how to support a colour-blind child.
Design for Colour Blindness
Practical design tips for creating accessible UI, charts, and graphics for colour-blind users.
Ishihara Test Explained
The history, science, and clinical use of the Ishihara pseudo-isochromatic plate test.
Ready to test your colour vision?
Try a free browser-based colour-vision activity. No account required. Results stay on your device.
What this library covers
A test result on its own is not much use. Knowing that you missed nine plates does not tell you what that means for driving, for a career, for your children, or for whether you should see anyone about it. These articles exist to answer the questions a result produces.
They are grouped around four things people actually arrive wanting to know.
Understanding the condition. What colour blindness is covers the biology — how three cone classes produce colour perception and what changes when one is shifted or missing. Types of colour blindness maps the terminology, which is a genuine obstacle: protan, deutan and tritan describe which cone is involved, while -anopia and -anomaly endings distinguish a missing cone from a shifted one.
Specific diagnoses. Protanopia, deuteranopia and tritanopia each cover one condition in depth: what causes it, which confusions it produces, how common it is, and what it means in practice.
Testing. The Ishihara test explained covers the plate method and why it works. How to use an online colour vision test is the honest account of what a browser-based screen can and cannot establish, and is worth reading before you trust any result — including ours. Can colour vision change later in life? addresses the distinction that matters most clinically: inherited deficiency is stable for life, so a genuine change in adulthood points to something else and should be assessed.
Practical guidance. Colour blindness in children covers early screening and school. Designing for colour blindness and making charts accessible are written for people building interfaces and data graphics.
How these articles are written
Every article is prepared by the ColorVision Editorial Team under our editorial and medical content policy. Factual claims are grounded in primary research, government health information, or established clinical references, and each article links its sources directly so you can check them rather than take our word for it. Each carries a last-updated date, and is revised when material information changes.
These are educational articles. They do not diagnose, and they are not a substitute for an examination. If your colour vision has changed, if one eye differs from the other, or if you have any other visual symptom, see an optometrist or ophthalmologist.
Reading alongside the activities
The articles and the tools are designed to be used together. If you have not been screened, the digit plate screen offers a figure-identification activity, while the 15-cap arrangement offers a shorter hue-order activity. Neither can determine a diagnosis or severity. If you are designing something, the simulator shows which distinctions your palette loses and the contrast checker confirms that what remains is legible.
Got Questions?
Frequently Asked Questions
Everything you need to know about colour blindness tests, how they work, and what to do with your results.
Where should I start if I just took a test?
Start with what colour blindness is for the underlying biology, then read the article covering your specific type — protanopia, deuteranopia or tritanopia — for what it means day to day. If you are unsure what your result indicated, how to use an online colour vision test explains what these screens can and cannot establish.
Is colour blindness a form of blindness?
No, and the name is genuinely misleading. Visual acuity is normal. What differs is discrimination between certain hues, not the ability to see. Very few people see no colour at all — that is achromatopsia, which is rare and usually accompanied by other visual differences. Most people with a deficiency see colour perfectly well; they just separate fewer of them.
Can colour vision be corrected?
Inherited deficiency cannot be corrected. Tinted lenses marketed for colour blindness increase the separation between certain confusable colours, which some people find useful, but they do not restore missing cone function and they can make other distinctions harder. Acquired colour vision loss is different: it may improve if the underlying cause is treated, which is why a change in adulthood should be assessed.
Which articles matter most for designers?
Designing for colour blindness covers palette construction and interface patterns, and making charts accessible works through data visualisation specifically. Both pair well with the simulator and the contrast checker.
How often is this updated?
Articles are reviewed when material information changes, and each carries its own last-updated date. Corrections are made when an error is substantiated — our editorial policy explains the process.
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