I believe it's important what interpreters wear. I remember a teacher of the deaf talking to me about it a few years and we were discussing what kind of dress was appropriate for interpreters. I found colours that were not dark the most distracting because of their hands being blurred with the colours. It's not such a problem at a close distance but further away, it does get tiring. I have eye problems as well, so it is even more important to me.
However, most interpreters these days seem to ignore this and they wear whatever they feel like... which is a pain. The most professional interpreters I have seen are the ones that follow the dress code very carefully.