Depends on what vision standard you are trying to waive, and how much you are talking about. I assume you are talking about visual acuity, ie 20/something other than 20 vision. Unfortunately, there is no definitive answer. If the AF needs pilots and you have a good recruiter/ROTC PAS, you can get a waiver for anything up to about 20/100. If the service doesn't need pilots or your recruiter won't go to bat for you, your chances of getting anything waived are small. Talk to your recruiter or local ROTC Det, and see what they have to say. If you make the Air Force want you, they will waive lots of things.
The Air Force has been granting waivers for years to Academy grads and navigators applying for pilot slots for years but has not given them to others. Call the nearest Air Force flight surgeon and ask the question. The AF is hurting for pilots and now might be a good time to get a waiver. I believe the Navy may approve laser eye surgery for it's pilots.
Just wanted to follow up. PRK is approved by the AF but only if they do it (For pilots as I understand it) LASEK or LASIK probably will not be approved because it involves cutting in to the corena where PRK just lasers the surface.
And if anyone is interesed here is the req regarding medical requirements for pilots and others.....