Dr Shinobu Ishihara introduced in 1917almost 100 years ago. Each of his tests consists of a set of colored dotted plates of which show either a number or a path. Since then this is the most widely used color vision deficiency test and still used by most optometrists and ophthalmologists all around the world.
There are other color blindness tests available, but none of them is as famous as the Ishihara plates. It is also well known, that even people with normal color vision sometimes struggle with this test. Nevertheless these plates are still in use in the absence of any better test.
There exist four different types of plates:
Vanishing design: Only people with good color vision can see the sign. If you are colorblind you won’t see anything.
Transformation design: Color blind people will see a different sign than people with no color vision handicap.
Hidden digit design: Only colorblind people are able to spot the sign. If you have perfect color vision, you won’t be able to see it.
Classification design: This is used to differentiate between red- and green-blind persons. The vanishing design is used on either side of the plate, one side for deutan defects and the other for protans.
Normal vision means you have normal photopigments, or color-detecting molecules, that allow you to see a full array of colors. Color blindness or deficiency, means your photopigments are abnormal causing your color perception to be limited and inaccurate.
There are 3 main types of colorblindness; take the test to find out if you could be colorblind. If you believe you could have color vision deficiency, consult with your eye care professional.
Normal colour vision