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Grades of colour deficiency and lantern test

Question

I understand there are various grades of Colour Deficiency, what test is used to determine this? Also where can you get a Lantern Test done?

Answer Written answer:
Qualified optometrist Simon Kay BSc(Hons) MCOptom answers this question.

The most common test used in the High Street is the Ishihara pseudoisochromatic plates where you have to read a number in a circle of dots. This grades colour deficiency only into moderate or strong. There are other tests used and the employer often states which test they require. However, if you pass the Ishihara test then you will not have a colour vision defect and will (or should) pass any other tests. The lantern test was originally designed to test the colour vision of railway workers and just tests a few primary colours. You can still be colour deficient and pass it.  It is very difficult to find a practice with a lantern test as they don't seem to have been manufactured for many years.

Optician's Biography

Simon Kay BSc(Hons) MCOptom has been a qualified Optometrist for over 30 years, and has a vast experience of almost all aspects of optometry. He joined Specsavers Opticians in 1993 first in Liverpool and for 15 years as a director of Lancaster and Morecambe. He served on many panels and committees whilst a director, including those responsible for IT design and professional advancement. He was regional chairman of the North West directors of Specsavers for over 12 years and as such was involved in almost all aspects of optometry on a business and professional level. He has been involved on the Local Optical Committee for many years and is currently Vice Chairman in his area.
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