Hey Alberto,
I'd eat normally before it as Farrell and and VC10 suggest.
Things I would do are get a good nights sleep before it and don't use your computer or watch TV too much beforehand.
If you are very tired then this can affect your ammonia levels in the urine beforehand, one of my friends had this problem. Focusing in the distance will help you beforehand for your eye test.
You could reduce your fatty type foods as well to cut down your cholesterol level -
http://www.google.co.uk/search?hl=en...lowering&meta=
The people there are very friendly and want you to pass, so there is nothing to worry about.
