Men have a much higher risk than women for colour vision deficiency. Red-green colour blindness is by far the most common type – it is found in approximately 8% of males and around 0.4% of females. This bias is because the genes that lead to red-green CVD are on the X chromosome, with males having just one X chromosome, whilst females have two.
For example, the son of a mother carrying the gene has a 50% chance of being CVD. Equally, a daughter to the same mother is not likely to be CDV unless she inherits two defective X chromosomes, which could occur if the father happens to be colour blind. In this case, the daughter still has only a 50% chance of being colour defective.
Blue colour blindness is far less common, being present in just 5% of all colour blindness sufferers. The genes affected are equal in both sexes.
You’re also more likely to have colour blindness if you:
- Have certain eye diseases, like glaucoma, age-related macular degeneration (AMD) or cataracts (cloudy areas in the lens of the eye)
- Colour blindness can also happen because of damage to your eye or your brain.
- Have specific health problems, like diabetes, Alzheimer’s disease, certain inherited retinal diseases or multiple sclerosis (MS)
- Take certain medicines
- Other much less common causes include shaken baby syndrome, accidents and other trauma, which may cause swelling of the brain in the occipital lobe
- a deficiency of vitamin A
We are often asked if eye colour has something to do with colour perception. Lighter coloured eyes are more prone to macular degeneration because they are more sensitive to light, so they may be affected in later years with a decline with a colour vision problem.
Everyone sees colour a little differently — even people who aren’t officially diagnosed as colour vision deficient as colour comes down to learned perception. Sometimes it can be caused by a change in chromosomes during development rather than being inherited.
If you think you may have CVD, talk with one of our qualified Optometrists for a test or try our colour vision testing kits.