What is colour vision deficiency?
- Part of the eye
- Colour signals
- Group
- Colour vision
- Vision functions involved
- Colour
- Main source
- NHS
Colour vision deficiency is a group of differences in colour perception. Most cases are inherited. Some develop because of another condition, an injury or medicines. Seeing everything in grey is rare.
Optometrist
An eye-care professional who tests sight, checks eye health and can refer you for specialist care.
How colour vision deficiency can affect day-to-day life
You may recognise some of these situations, or none of them. The point is to find help with the things you want to do.
School worksheets
Colour can carry an answer a child cannot reliably tell apart.
Add written colour names and patterns, and tell the teacher about the diagnosis.
Charts and travel maps
A line may be hard to follow when its colour is the only clue.
Use route names, symbols and direct labels.
Clothes and shopping
Matching shades can take extra checking.
Keep colour names on labels or ask for confirmation when the shade matters.
Changes you may notice
- Difficulty separating shades or following colour-only information.
- In children, unexpected colour choices or difficulty with colour-sorting tasks.
Everyone is different. Symptoms on their own cannot identify a condition.
What to do about a new or sudden changeAssessment and care
Ask an optometrist for a colour-vision assessment. Routine eye tests do not always include one. Online plates cannot replace a professional test. New changes need checking. Do not stop prescribed medicines yourself.
Explore the different types
Red-green and blue-yellow colour vision deficiency have their own guides. Achromatopsia is a separate, rare condition which also affects detail vision and comfort in bright light. A greyscale demonstration does not represent the common colour-vision deficiencies.
How vision is affected
These topics explain the parts of vision involved. They do not predict your sight, diagnose anything or show the condition itself.
Colour
Colour helps you tell things apart. Clear labels and patterns make the same information readable without relying on colour.
Open the colour labRelated guides: Red-green colour vision deficiency, Blue-yellow colour vision deficiency, Achromatopsia
Everyday support
Ask for words, shapes or patterns alongside colour. Explain the particular tasks you find difficult rather than assuming one palette works for everyone.
A question to take to your appointment
Which type do I have, is this longstanding or acquired, and which adjustments would help?Prepare your appointment checklist
Sources and review status
Sources checked 4 October 2026. Educational draft, not yet clinically reviewed. No clinician has endorsed this page. Follow the advice of your own eye-care team.
How this content is prepared