I'm another story of losing a flight slot right before commisioning. Thankfully, my story has a happy ending as I just got picked up for the AD board.
I also had PRK, and you do have to weigh the risks vs. the possible rewards. For me, I was Nav waiverable, so I went for the chance to be in charge. I had some complications (long story PM if you want to hear it) but I did it. IF you chose PRK, understand you MUST wait 1 year from surgery date before they will evaluate you for a waiver (that's right PRK automatically DISQUALIFIED me from flying until my waiver was approved). Keep that in mind when you think about time deadlines for active duty boards.
First, fight as hard as you can BEFORE you commision, the game completely changes after you pin on those butter bars, and if you can get things fixed, earlier is better.
Failing that, make sure you get your medical stuff taken care of and go and be a sharp troop. Let your chain know your intentions to go for a UPT slot, but don't just sit there waiting for them to hand it to you, do your current job well. You don't have to be God's gifts to CGOs (just look at me) but don't piss off your commander. Be the troop people want to help out, and enjoy the highlights that every job in the AF has. (It might not be flying, but there is ALWAYS some positive in what you are doing in life).
Something to consider, does the career field you are going into have a service commitment? I don't know, but be careful for things such as AFIT that will keep you from cross-training.
Well, there is my slightly more then .02. If I've got anything in here wrong or outdated, I apologize. This is the way the rules were for me. Remember the AF has one constant, change.
Good luck and keep trying!