Colour vision deficiency (colour blindness)

• you or your child have signs of colour vision deficiency

There are 2 main tests for colour vision deficiency:

• the Ishihara test, where you'll be asked to read images made up of coloured dots
• colour arrangement tests, where you'll be asked to put coloured objects in order of what shade they are

Colour vision testing is not part of the routine NHS eye test, but you can ask your opticians for it if you think you or your child needs it.

Tests are available online, but it's important to get checked at an opticians if you have concerns about your vision.

It's not known exactly what causes colour vision deficiency, but it's thought to be a problem with the signals from your eyes to your brain.

It can be passed on in families and some people are born with it.

Colour vision deficiency can also sometimes be caused by:

• eye conditions, such as glaucoma
• other conditions such as diabetes, liver disease and multiple sclerosis
• an eye or head injury
• a stroke
• taking certain medicines

There is currently no treatment for colour vision deficiency that runs in families. Most people adapt to seeing colours differently.

If your colour vision has been affected by an underlying medical condition or by medicines, getting treatment for the condition or changing medicines may help.

There is no treatment for colour vision deficiency that runs in families, but people usually adapt to living with it.

Colour vision deficiency can run in families. It can also be caused by medical conditions or certain medicines.