Glasses are allowed in the military. If you enter recruit training with glasses, they make you wear the ugly birth control glasses (or as they called it, contraceptive eyewear) but I digress.
You can get LASIK or PRK eye surgery in the military, but you have to put yourself on a waiting list and the wait can be a bitch. I went ahead and got PRK eye surgery a few years back, I got it by a civilian doctor who had a hot reputation, and paid 5 grand out of my own pocket. It was well worth it, I went from wearing glasses with 20/400 to perfect 20/20, plus I got a waiver to join the NavSpecWar pipeline. I had to wait 6 months at a minimum before I had to start the waiver paperwork though, so BuMed can make sure that my eyes were absolutely ok.
You can get a waiver for PRK for NFO (Naval Flight Officer) and I heard occassionally you can get it for SNA (Student Naval Aviator) but LASIK is still absoutely disqualifying last time I heard. It's simply too risky for the high level jobs that SpecWar, NFO, and SNA requires, but it's definately good to go for other jobs.
(btw guys, if you hadn't figured it out yet, I'm back for a while, then I'll probaly dissapear again without notice).