Colour vision deficiency, commonly known as 'colour blindness' is where a person can see different colours but is unable to make out the difference between some complimentary colours. It is not related to visual acuity and is most commonly due to an inherited condition.

We have 3 types of colour receptors in our eyes, red, green and blue as well as black and white receptors. A colour vision deficiency comes from a lack of one or more type of colour receptor. It is possible to have all 3 colour receptors missing resulting in black and white vision.

Red/Green colour vision deficiency is the most common form and a rare percentage has difficultly with Blue/Yellow colour; however there is no commonly available test for this.

About 10% of the male population have a colour perception defect and is very rare in females.

Colour vision deficiency is tested using the 'Ishihara' colour vision test plates. They are a collection of 38 plates filled with coloured dots. The dots are coloured in different shades of a similar colour and a number is hidden inside with shades of another colour. A version for children has also been developed using animal shapes.


Thistle Street Medical Centre
Level 1, 36 Thistle Street West
South Launceston, TAS 7249

4 Eastland Drive
Ulverstone, TAS 7310

phone 03 6344 1377
fax 03 6344 1577

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