What is a colour vision test?
A colour vision test identifies whether you have any difficulty distinguishing between certain colours — commonly known as colour blindness, although total colour blindness is extremely rare. The most common form is red-green colour vision deficiency, which affects approximately 1 in 12 men and 1 in 200 women in the UK. Many people live with colour vision deficiency without realising it, particularly if they have had it from birth.
The most widely used screening tool is the Ishihara test, which consists of a series of plates covered in coloured dots with numbers or patterns hidden within them. People with normal colour vision will see the numbers clearly, while those with a colour vision deficiency may see different numbers or none at all. For more detailed assessment, tests such as the Farnsworth D-15, the City University Test, or the anomaloscope can determine the exact type and severity of the deficiency.
Knowing your colour vision status is important for certain careers. Roles in the armed forces, police, fire service, aviation, maritime, electrical engineering, and some healthcare positions require specific colour vision standards. A colour vision test is also routinely part of children's eye examinations, as early detection allows teachers and parents to make appropriate adjustments to support the child's learning. While there is currently no cure for inherited colour vision deficiency, awareness of the condition and practical strategies can make a significant difference.
Who needs a colour vision test?
- Children having their first eye test — early detection helps with learning support
- Anyone applying for a career that requires specific colour vision standards (e.g. armed forces, police, fire service, aviation, electrical work)
- Adults who suspect they may have difficulty distinguishing certain colours
- People with a family history of colour vision deficiency
- Workers in industries where accurate colour recognition is safety-critical
What to expect during a colour vision test
- 1You are shown a series of Ishihara plates — circular patterns of coloured dots with numbers embedded in them
- 2You are asked to identify the numbers or trace a path through each plate
- 3The test is performed in good lighting conditions
- 4If a deficiency is suspected, further tests may be used to determine the type and severity
- 5Your optometrist will explain the results and any practical implications
- 6A certificate or report can be provided for employers if required
How much does it cost?
Usually included as part of a standard eye test at no extra cost. If a standalone assessment is needed, expect to pay £15–£30
How often should you have this test?
Once is usually sufficient if results are normal; re-testing only if there is a clinical reason (e.g. acquired colour vision changes from medication or disease)