A Guide to Colour Blindness

What is colour blindness?
Also known as Colour Vision Deficiency (CVD), if someone is affected by colour blindness, they will have difficulty distinguishing between certain colours or will perceive them differently. Light travels to the back of the eye to the retina which is covered in many light-sensitive cells called rods and cones. The rods don’t have much to do with colour vision but are very sensitive to light and help us to see at night. The cones are the cells that control colour vision. Each colour has a different wavelength of light and when the cone cells detect the light, they send signals to the brain, turning the signals into images.

Colour blindness occurs when the retina doesn’t respond to the many wavelengths of light to match the colour. Colour blindness is usually inherited and affects more males than females. It is regularly present from birth so it is a good idea when having your child’s eyes tested to also request a colour vision deficiency test. In some cases, colour blindness could also be a result of physical damage to the eye, illness, or age. It is very rare someone will have complete colour blindness (achromatopsia), those that do can only see shades of grey, white and black.

Certain occupations can be impacted by colour blindness, for example, a job that involves a lot of colours like a graphic designer or a painter. Or where distinguishing between colours plays a vital part in safety, for example, electricians working with wiring systems.

Types of colour blindness

The most common form of colour blindness and is a decreased sensitivity to red-green colours making green look red.
Less receptive to red colours and makes red, orange, and yellow look more green.
Reduced sensitivity to blue-yellow colour. Makes it difficult to distinguish between blue and green and between yellow and pink.

Colour blindness symptoms
Symptoms of colour blindness can vary. Many have very mild signs that they're unaware of until a colour blindness test is done.

Some signs of colour blindness are:

• Difficulty distinguishing or identifying colours
• Difficulty distinguishing shades of colours, especially of red and green,
or shades of green and blue
• Difficulty perceiving the brightness of colours
• You previously have been able to see the full range of colour
but have developed colour vision problems

If you might be experiencing some of the above symptoms you can book an eye test with Oscar Wylee to check for colour vision deficiency.

Ishihara Plate Test

There are many different tests available to test for the different types of colour blindness. At Oscar Wylee, our optometrists use the Ishihara Test, the most commonly used test to check for red-green colour vision deficiency.

It uses images or “plates” made up of various sized coloured dots in two or more colours and requires you to detect a number or line within the dots. If you have trouble seeing red and green, those numbers will be difficult to see or may not be seen at all.

Due for an eye test? Book now:

We recommend that everyone should have an eye test with an optometrist at least once every 2 years.

Oscar Wylee offers bulk billed eye test, so there are no out-of-pocket expenses for eligible Medicare card holders.