Colour Blindness

What is colour blindness?

Colour blindness, or colour vision deficiency, means you see colours differently and may struggle to tell certain shades apart. It doesn’t mean seeing in black and white. Red‑green colour blindness is most common, affecting around 1 in 12 men and 1 in 200 women.

What are the symptoms of colour blindness?

The main symptom of colour blindness is difficulty distinguishing between colours or making mistakes when identifying colours. You might not be aware you have it until it's pointed out or you undergo a colour eye test. Symptoms can range from mild to severe. Common signs include:

Difficulty telling reds and greens apart: This is the most common issue, especially in red‑green colour blindness. Traffic lights can be a challenge, though they are designed with this in mind (red is always at the top).
Confusing colours: You might mistake blue for purple, or orange for red. For example, you might have trouble telling if a banana is ripe.
Colours appearing dull or washed out: Colours may seem less vibrant than they do to people with normal vision.
Trouble with colour‑coded information: Difficulty reading colour‑coded charts, graphs, or maps. This can have occupational considerations, for example, for electricians working with coloured wires.
Sensitivity to light: In some rare and severe forms of colour blindness, like monochromacy, individuals may experience increased light sensitivity.

What causes colour blindness?

So, what causes colour blindness? In the vast majority of cases, it's a matter of genetics.

Inherited condition

Most people with colour blindness are born with it. It's a common inherited condition passed down from parents to their children on the X chromosome. This is why red‑green colour blindness is much more common in men.

This is why red‑green colour blindness is much more common in men. A man only needs to inherit the gene from his mother to be colour blind, whereas a woman needs to inherit it from both her father and mother.

Acquired colour blindness

You can develop colour blindness later in life, often due to an underlying health condition like glaucoma, diabetic retinopathy, or multiple sclerosis. It can also be caused by certain medications, ageing, or an injury to the eye.

If you’ve noticed any changes in how you see colours, it’s a good idea to book an eye test. Your optometrist can check for any signs of underlying problems and help you understand what’s going on.

How is colour blindness treated?

There’s currently no cure for inherited colour blindness, but there are ways to manage it and adapt day to day. If colour blindness develops later in life, treating the underlying cause, like an eye condition or medication side effect, may help restore some colour vision.

Some people find colour blind glasses helpful, especially for red‑green colour blindness. These special lenses filter certain wavelengths of light to make colours appear more distinct, though they don’t work for everyone. There are also apps and accessibility tools that can help identify colours, along with simple things like learning the order of traffic lights or relying on labels, to make everyday tasks easier.

Book an eye test