Good luck. It really is very simple. Just a basic eye test with a couple of extras.
Some people seem to get drops as standard, and other places only use the drops if they deem it necessary.
Where I go, they have all the equipment in a small alcove like room, with the lights off. So you walk in and sit with your back to the open doorway, facing the dark room. Then they do about 3 other tests and by the time they get to photographing the back of the eye, your pupils have expanded enough to not need drops. Works like a charm. Then they take you into a not-very-bright area for a minute or two while your eyes readjust to the light.
Don't forget to pop back and tell us how it goes!