Colour blindness testing assesses a person’s ability to distinguish colours and identifies congenital or acquired colour vision deficiencies. It is used in clinical evaluation and for occupational screening.
Test Types
Common methods include pseudoisochromatic plate tests, which present numbers or patterns hidden within coloured dots, and arrangement tests, where coloured caps must be placed in order. More advanced systems use computerised matching tasks or anomaloscopes.
- Plate tests are quick and suitable for initial screening
- Arrangement tests help classify type and severity of deficiency
- Anomaloscopes provide precise quantification but are less widely available
- Testing conditions require standardised lighting and viewing distance
Clinical and Occupational Use
Results distinguish between congenital red-green deficiencies, rarer blue-yellow defects, and acquired colour losses due to eye or neurological disease. They inform career guidance and safety assessments in roles where accurate colour discrimination is critical.
- Changes over time may indicate acquired pathology rather than inherited traits
- Documentation helps support reasonable adjustments in education and work
- Interpretation must consider age, literacy, and familiarity with test symbols
- Testing is often repeated if results are borderline or inconsistent
