Specialty Vision · Vision Simulator
Colour vision
Colour vision deficiency ('colour blindness') rarely means seeing in black and white — it means certain colours, most often reds and greens, look alike and are easily confused. It is usually inherited and lifelong.
How colour-vision deficiency looks
“Colour blindness” rarely means seeing no colour at all — usually certain colours become hard to tell apart. The most common types make reds and greens easy to confuse. Pick a type to see the difference on the colour chart.
Overview
Colour vision comes from three types of cone cells in the retina, tuned to red, green and blue light. In colour vision deficiency one cone type is missing or works differently, so the brain can't tell certain colours apart. The most common form is red-green deficiency; blue-yellow deficiency is rarer; and total colour blindness (achromatopsia) is very rare. Most people with red-green deficiency see a full, bright world — they simply confuse particular shades.
Symptoms
- Confusing reds, greens, oranges and browns with one another
- Trouble telling traffic lights, ripe fruit, or coloured charts and maps apart
- Difficulty with colour-coded information — status lights, graphs, wiring
- Often not realising colours are being confused; many people only find out on a test
Causes
- Usually inherited — a change on the X chromosome, which is why red-green deficiency is far more common in men
- Less often acquired later from eye disease (macular or optic-nerve disease), some medications, or ageing
- Total colour blindness (achromatopsia) is rare and caused by absent or non-working cones
Treatment
Inherited colour vision deficiency can't be cured, but it rarely needs medical treatment. Special tinted glasses or contact lenses help some people tell confusable colours apart — they don't restore normal colour vision. Simple strategies (labelling, using brightness and position rather than colour alone, and device accessibility settings) make daily life easier. If colour vision changes suddenly or in one eye, that suggests an acquired cause worth checking.
When to see an eye doctor
Inherited colour blindness is stable and not dangerous, so it usually only needs a one-time diagnosis — useful for school, certain careers, and understanding your vision. See an eye doctor promptly, though, if your colour perception changes suddenly, worsens, or differs between your two eyes, because a new colour-vision change can be an early sign of macular or optic-nerve disease.
Seek urgent care for:
- A sudden change in how you see colour
- Colour vision that is noticeably worse in one eye than the other
- Colour change together with vision loss, eye pain or other new symptoms
Frequently asked questions
Do colour-blind people see in black and white?
Almost never. Total colour blindness (seeing only shades of grey) is very rare. The vast majority of people with 'colour blindness' have red-green deficiency: they see a full, colourful world but confuse certain shades of red, green, orange and brown.
Is colour blindness more common in men?
Yes. The common red-green types are carried on the X chromosome, so they affect roughly 1 in 12 men but only about 1 in 200 women.
Can colour blindness be cured?
Inherited colour blindness can't be cured. Tinted 'colour-correcting' glasses help some people distinguish confusable colours, but they don't create normal colour vision. Most people adapt well using brightness, position and labels.
Can colour blindness appear later in life?
Inherited colour deficiency is present from birth. But a new or one-sided change in colour vision later in life can signal eye disease — such as macular or optic-nerve problems — and should be checked by an eye doctor.
Sources
- What Is Color Blindness? — American Academy of Ophthalmology
- Color Blindness — National Eye Institute