Glasses or contacts? In my opinion, you need both. I prefer the way I look without glasses, so I wear my contacts on a daily basis. For the pre-clinical years folks - I also wore my contacts every day in anatomy lab even though there was some tiny blurb on some form about not doing so. Remember that most body preservatives these days have no formaldehyde or only a tiny amount - phenol (also a carcinogen, I'm afraid) is the primary preservative. My contacts were occasionally a tiny bit irritated on leaving the lab, but I never had any ongoing problems.
However - you also need glasses. There's going to be some night when you're pulling an all-nighter and you leave your contacts in too long. Next day when you go to the exam, it's much better to wear your glasses. Trust me, you'll quit caring much about how you look - I went to exams with dirty hair more than once to get an extra hour's studying in (I did always put on clean underwear, deodorant, and I brushed my teeth - common courtesy). I went to exams a couple of times with swollen contacts from wearing them too long and had a horrible time reading the page - that's an experience I wouldn't wish on anybody else.
You also need glasses for call for your clinical years. When you're sleeping, you don't want your contacts in - but if you get paged urgently, you don't have time to be putting your lenses in.
