A colour blind test assesses how well someone can distinguish different colours, usually to detect red-green colour vision deficiencies. Many people are born with mild defects and may not notice problems until tested.
Types of testing
Simple screening can be done quickly in clinic.
- Plate tests present numbers or shapes made of coloured dots
- People with colour deficiency may not see some figures correctly
- More detailed tests can grade the severity and type of defect
- Some occupational assessments use tailored colour vision standards
Practical implications
Most colour vision defects are stable and cannot be cured.
- Important for career guidance in jobs that rely on accurate colour discrimination
- Helps explain difficulties with traffic lights, wiring, or colour‑coded charts
- Children with suspected problems should be tested early
- Changes later in life can signal retinal or optic nerve disease and need specialist review
