[quote name='masked lemon']What is the deal with the little flap of skin? What does it look like?[/quote]
God this is going to be hard to do without pictures (and with 4 1/2 years since I heard the description)...
Okay, the goal of Lasik, PRK, and maybe any other eye surgery to improve vision is to flatten part of your eye with a laser. That little flattened part of your eye will wind up working like a pair of glasses.
First off, think of your whole eye as a hardboiled egg standing up with the yolk being the part that needs to be flattened. In Lasik, a laser will slice through most of the top of the egg, leaving a flap that can be lifted to expose the yolk inside. Once that slice is made, the doctor will lift the flap, zap the yolk with a laser to flatten it, and then lay the flap back down over the now-flattened yolk. Surface tension will have no problem holding that flap in place during normal activity (think about two pieces of Saran wrap stuck together. Swimming might require goggles but I'm not sure. Lasik is great because the whole process is painless as can be.
With PRK, the doctor intially takes a little scrubbing thing and brushes off the top layer of skin, exposing the part of the eyeball that needs to be flattened without any cuts. After that is done, he takes a laser, flattens the part of the eyeball to meet your perscription and allows the skin that was previously brushed off the surface of your eye to grow back naturally. The problem with PRK is that the growing back process hurts, alot. I was crazy on painkillers for five days and I had to spend something like six months afterwards wearing sunglasses whenever I was outside. That said, now that the healing is long finished, my eyes work fine and don't have any little cuts in them.