I spoke to the head of the AMS Ireland (Dr Laffan) and he told me that if you pass the holmes wright test once then he will not require you to do the test again. His opinion is that if you are declared Colour safe then you are for life. I have passed the FALANT but have never taken the holmes wright. I will be taking the test in early jan and I'll post results here.
I mentioned this in an earlier post, I passed one of the FAA alternative tests called the Titmus vision tester. It uses Six selected ishihara plates but the difference is that they are lighted correctly. I was able to see the numbers in the testing machine but when the same six plates were shown to me out of the book I could'nt see them. It is possible that a lot of people are being declared colour deficient because the test is not being given properly.