No need to be nervous Helen. The only thing they do is put a couple of drops in your eyes and this can sting a bit for a few seconds. After that (and a bit of a wait whilst the drops take effect!) you just put your chin on a machine and look at a light whilst they take a picture. It's normally just one picture per eye, but sometimes they do more than one if the frst one doesn't look good enough. The main thing to remember is that it can be difficult to focus afterwards, so no driving and wear sunglasses even if it's not sunny! All wears off in a few hours.