Color Blindness

Colour blindness is a usually-inherited difficulty in distinguishing certain colours, most commonly red from green. It affects about 1 in 12 men and 1 in 200 women. It is not a disease — it's a variation in how the eye's colour-sensing cones work, and people with it see and function fine in daily life.

Types

• Red-green — most common, X-linked, so mostly affects boys. Inherited from the mother.
• Blue-yellow — rarer.
• Complete colour blindness — very rare.
• Acquired colour vision changes from diabetes, glaucoma, optic nerve disease, medications (some antibiotics, antimalarials, anti-TB drugs including ethambutol) — worth investigating if new.

Practical implications in India

• Certain careers with official colour-vision requirements — armed forces, civil aviation, railways, some merchant navy posts, fire service. Check eligibility early; tell your child's school if they're considering these.
• Driving is generally fine — most people recognise traffic lights by position, not only colour.
• Electrical wiring, map reading, sports (red ball on green field), and some lab/medical work may need help from a colour-seeing colleague.
• Apps and filters can name colours on demand; colour-correcting glasses help some people (but don't work for everyone — try before you buy).

Testing

• Screening with Ishihara plates at an eye clinic — quick, painless, often done at a preschool or school check.
• A new finding of colour-vision loss in an adult should be investigated — it can indicate optic nerve or retinal disease.