Colour blindness

Also known as colour vision deficiency, colour blindness is when someone has difficulty or cannot distinguish between certain colours, usually with shades of red, green, yellow and more rarely, blue.

Types of colour blindness

This type affects the sensitivity to red light.

This affects the sensitivity to green light.

Both of these types are also known as ‘red/green’ deficiency and are the most common type of colour vision problems. People with this kind of colour vision deficiency may find it difficult to tell the difference between shades of red, orange, yellow, brown and green; different shades of purple; or confusing red with black.

This is a rarer type, also known as ‘blue/yellow’ deficiency, and causes difficulty with blue, green and yellow colours.

In very rare cases, there may be no colour vision at all, just varying shades of white, grey and black.

Colour blindness happens when the colour sensitive cells within the eye aren’t working properly or are missing.

Most cases are caused by an inherited genetic condition, usually from the mother’s side.

Anyone can have colour vision deficiency, but it’s much more common in males.

It can also develop later in life as a result of health conditions like:

Or as a side effect to certain medications.

Diagnosis of colour blindness

There are two main tests used to diagnose colour blindness:

• The Ishihara test – You’ll be asked to read the numbers on an image made up of lots of coloured dots.

• Colour arrangement – Various forms of this tests exist. They involve matching or arranging coloured objects or images in a book in order of their shades. Colour vision tests are not normally part of a routine eye exam, so please make sure you let us know when booking your appointment if you would like one.

Colour vision tests are not part of our usual eye exams, so please make sure you let us know if you’d like one.

Treating colour blindness

Because the vast majority of colour vision problems are something we are born with, there is no treatment for colour deficiency. Those with the condition will find that they can adapt to it to some extent but may not be able to pursue professions where accurate colour vision is required.

You might also find the following tips helpful:

• Many computers and phones now have settings to help people with colour vision deficiency.

• Invest in some good quality lighting to help your colour vision at home.

Did you know?

At Specsavers, colour vision tests are not part of the usual eye exam, so make sure you let us know if you’d like one. If you have any concerns about your colour vision, it's important to see your optometrist or GP.