colour blindness


Sep 30, 2008
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Hey guys,

im red/green colour blind says my optician, but i can see object that are red and green fine, just those crazy dots that sometimes i cant do.

Do you know what tests the marines do for colour blindness? and what scores do you have to get?

Thanks :)


Jul 10, 2007
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You need to be CP4 or better to join as a Royal Marine.

The grades are worked out as follows:

Colour Perception (CP) grade 1

The correct recognition of coloured lights shown through the small paired
apertures of the Holmes Wright lantern at LOW brightness at 6 metres
distance in complete darkness.

CP 2

The correct recognition of the first 17 plates of the ISHIHARA test shown in random sequence at a distance of 50 – 100 cm under standard fluorescent lighting supplied by an artificial daylight fluorescent lamp.

CP 3

The correct recognition of coloured lights shown through the paired
apertures on the Holmes Wright lantern at HIGH brightness at 6 metres
distance in complete darkness.

CP 4

The correct recognition of colours used in relevant trade situations, and
assessed by simple tests with coloured wires, resistors, stationary tabs, etc.

CP 5 Unable to pass any of the above tests.

1. Ishihara plates are to be used as screening for all entries.

2. Candidates who pass the Ishihara test are graded CP2 and require no further testing except for those whose critical visual task requires a categorisation of CP1.

3. Candidates who fail the Ishihara test are further tested for CP3 or CP4 according to requirement.

4. The Holmes Wright Lantern is to be used to discriminate CP1 and CP3. Appropriate trade testing (normally using a wire board and stationary tabs) will discriminate between CP4 and CP5.

Ishihara Book Test

1. Examination Method:

a. The test is conducted using only good diffused daylight directly onto the test plates or the alternative illuminant, all other light being excluded.

b. The test plates are presented to the examinee at a distance of 50-100cm
(20-40 inches) for not more than 5 seconds. The examinee may wear spectacles if appropriate. The winding line plates for illiterates normally need not be presented.

c. Each number is read aloud by the examinee. They are not allowed to trace or handle the plates.

d. The number of plates miscalled is recorded in the box on the examination form.

2. Assessment: If no error is made the examinee is graded CP2, but it should be noted that certain numbers might be miscalled by colour normals particularly when under stress. If not more than 3 plates are miscalled, the miscalled plates are shown again. If no errors are made on the second presentation, a grading of CP2 may be given.

Those failing the test will require further assessment with lanterns or trade testing to determine if their colour vision is CP3, 4 or 5.

Lantern Test

3. The Holmes-Wright Lantern Test is constructed to simulate in controlled conditions, the critical visual task of seamen. The test is usually performed by approved persons. The lantern is regarded as a form of trade test displaying pairs of vertically arranged lights in a combination of red, green and white. These are viewed at a distance of 6m (20 feet) either by direct vision or mirror reversal, in light surroundings or in total darkness as laid down in current instructions.


Oct 9, 2008
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i just managed to pass mine on cp4 *text deleted*, i had the same problem could see colours
fine except when its being tested : ).
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