The only reference cited by Dr Pooshan Navathe (Principal Medical Officer, CASA) reports that there are differing standards for assessing colour vision amongst ICAO member countries (Watson DB. ‘Lack of international uniformity in assessing colour vision deficiency in professional pilots’ Aviat Space Environ Med 2014 Feb; 85(2):148-59).
If the Watson DB is who I think he is (PMO NZ CAA), Dr Navathe shared offices with him just prior to Dr Navathe moved to Canberra.