Colour vision deficiency, also known as colour blindness, is a condition that alters the way in which the eye perceives colour; but what does this actually mean?
The eye sees difference between colours thanks to the light that comes in. The cones, which are light-sensitive cells of the retina, control colour vision; and there are several types of pigments in the three types of cone cells that are responsible for the way our eyes see light.
What happens in the eyes of people with colour blindness is that the cones do not respond to the wavelengths variations of light that normally allows us to see different colours.
It affects approximately 4,5% of the population in Britain and around 300 million people worldwide. However, there are lot of people who never realise they have some kind of a colour deficiency as they do see colours, just not the same as other people.
Types of colour blindness:
People with colour blindness perceive light slightly out of alignment depending on which of their eye cone is affected. There are three main types of colour blindness:
- Reduced sensitivity to red light. The red cone photopigment is damaged and doesn’t work correctly, which leads to seeing red more like green, brown or yellow.
- Reduced sensitivity to green light. This makes people see redder, and it is the most common type of colour blindness.
- Reduced sensitivity to blue light, which is extremely rare. People with this kind of colour blindness have problems seeing blue and yellow colours. It is usually acquired due to an eye condition.
Finally, we can also speak of total colour blindess or achromatopsia. It happens when the majority or all of the cone cells in the retina are missing or not working properly. People with achromatopsia might see in monochrome (greys, blacks and whites) and have reduced visual acuity.
What causes it?
The condition is most commonly passed through genetics. Many people can be just carriers without even realising as it can be a recessive gene. Sometimes it can develop with age.
Colour blindness can also be caused by other conditions; such as diabetic retinopathy, glaucoma, macular degeneration, Alzheimer or multiple sclerosis. Any damage to the eyes or our optic nerve, be it due to trauma or by other conditions, can also cause colour blindness.
In some cases, it can also occur as a side effect of certain medicines.
How to treat it?
Although there is currently no treatment for colour blindness, there are special lenses and glasses that can help enhancing colour perception. An optician will be able to recommend a suitable pair.
In the case of severe colour blindness, such as achromatopsia, visual aids, like magnifiers, can help with the loss of visual acuity, while specialised filter sunglasses can minimise the impact of the increased sensitivity to light that accompanies this condition. A low vision specialist will be able to assist with other symptoms.
Luckily, most people with colour blindness don't experience any vision loss. However, it's always important to see your doctor or ophthalmologist if you notice any changes in your vision, be it difficulty to distinguish colours or others, so you can identify any sight problems early on an receive proper treatment if needed.