It's pretty much get the slot, get through UPT, and once you're in - once you're an officer and a pilot, they will work with you on your medical needs.
They've already trained you so they're gonna try to keep you so long as you're not a danger to the mission. Before going through that training though - and especially today (economy and all that) then a medical DQ could hit you hard.
Edit: While I haven't met fighter pilots who wear contacts or glasses, I have met a number of heavy pilots who do.