Welcome to the forum! The rules are made by EASA now and the full EASA rules for medicals are found in EASA Part-MED. See HERE
From the AMC it says;
AMC1 MED B.075 Colour vision
(a) At revalidation, colour vision should be tested on clinical indication.
(b) The Ishihara test (24 plate version) is considered passed if the first 15 plates, presented
in a random order, are identified without error.
(c) Those failing the Ishihara test should be examined either by:
(1) anomaloscopy (Nagel or equivalent). This test is considered passed if the colour
match is trichromatic and the matching range is 4 scale units or less; or by
(2) lantern testing with a Spectrolux, Beynes or Holmes-Wright lantern. This test is
considered passed if the applicant passes without error a test with accepted
Hope this helps.