Colour blindness is an umbrella term for a range of vision deficiencies that affect how a person sees colour. It doesn’t always mean seeing the world in black and white—most people with colour blindness have difficulty distinguishing between specific colours, usually reds, greens or blues.

How Common Is It?

In the UK, colour blindness affects approximately 4.5% of the population. It’s far more common in men: around 1 in 12 men are affected compared to 1 in 200 women. This is because the most common types of colour blindness are linked to a gene on the X chromosome, which males (XY) have only one of, whereas females have two (XX). People of Caucasian descent are more frequently affected than those of African or Asian descent.

Types of Colour Blindness

There are several types of colour vision deficiency, the most common being:

  • Protanomaly: Reduced sensitivity to red light
  • Deuteranomaly: Reduced sensitivity to green light (the most common form)
  • Tritanomaly: Reduced sensitivity to blue light (very rare)

When someone cannot perceive a certain colour at all, different terms are used:

  • Protanopia: Inability to see red light
  • Deuteranopia: Inability to see green light
  • Tritanopia: Inability to see blue light

Some people have reduced sensitivity to more than one colour, most commonly red-green colour blindness. This can affect the ability to distinguish colours like brown, orange, green and blue.

A very rare type is monochromacy (achromatopsia), where people see only in shades of grey. It affects around 1 in 30,000 people.

Causes of Colour Blindness

Most colour blindness is inherited and present from birth. It is usually caused by faulty light-sensitive cells (cones) in the retina. These cells fail to detect certain wavelengths of light properly.

Colour blindness can also be acquired later in life, due to:

  • Eye diseases (e.g. glaucoma, macular degeneration)
  • Health conditions (e.g. diabetes, multiple sclerosis, liver disorders)
  • Medications with visual side effects
  • Injury to the eye or brain

Living with Colour Blindness

While colour blindness can present daily challenges, many people adapt well. Common issues include:

  • Choosing clothing or matching colours
  • Reading colour-coded charts or graphs
  • Cooking (e.g. judging whether meat is properly cooked)
  • Interpreting traffic lights or warning signs

However, with the right strategies and support, most people with colour blindness lead full and independent lives. Many apps, filters and tools now exist to help people distinguish colours more easily.

How Is It Diagnosed?

Many people don’t realise they are colourblind until they struggle with certain tasks. One of the most widely used tests is the Ishihara Plate Test, which involves identifying numbers or shapes hidden in a field of coloured dots. People with colour vision deficiencies will struggle to see certain patterns.

Colour blindness can also be diagnosed through:

  • Anomaloscope tests
  • Cambridge Colour Test
  • Farnsworth-Munsell 100 Hue Test

Learn more about the Ishihara Plate Test via specsavers.co.uk.

Can It Be Treated?

There is currently no cure for inherited colour blindness. However, tools such as colour-corrective glasses or contact lenses may help some individuals, although results vary from person to person.

For acquired colour blindness, treating the underlying cause (like switching medications or managing a medical condition) may sometimes reverse or improve symptoms.

If you suspect you or your child may have colour blindness, speak to an optometrist for advice and testing.