Colour vision deficiency (commonly called colour blindness)
First documented - 1798 (chemist John Dalton)
Colour vision develops- 2 months age
Genetic condition- linked to X chromosome
Hence males are more affected than females (8% vs 0.5% approx)
Caused by - faulty/ missing cone cells in retina which are responsible for normal colour vision
Types :
- Anomaly - abnormal
- Anopia- absence
- Protoanomaly / protoanopia - red cones ffected
- Deuteranomaly/ deuteranopia- green cones affected
- Tritanomaly/ tritanopia- blue cones affected
Tests for diagnosis-Ishihara test- a series of 38 plates to determine any defect
Cure - no medical treatment at present
Managed by- use of filtering glasses
Activities to avoid- driving
Drugs that can cause it- Ethambutol, Hydroxychloroquine, Digoxin, Sildenafil
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MBH/DB