did u fill in the medical form prior to your final board. on the form it asks for a score in the ishihara plates test, so if they accepted u for a final board with a less than perfect score in the test then presumably they will not expect a perfect score if u then take the test at their medical. i don't actually know the answer to the question but i would assume they would offer an alternative to the plates seeing as they have accepted u knowing that u may not pass the ishihara test.
cheers
Rod