I've had LASIK and am generally pleased. I am a solid 20/12 in one eye and 20/15 to 20/20 in the other (luck of the draw I suppose). I had a mild bit of DLK (hazyness caused by white blood cells collecting in the interface where the flap is) which took time to go away while on steroid drops. I did, however, for whatever reason, have a bit of ligament stretch in one of my eyelids from the procedure, and am probably going to have that "fixed" with some plastic surgery (and while I'm doing this get an "eye lift").
As far as what separates LASIK from PRK- during PRK, the epithelium is chemically removed (typically with alcohol) and the laser ablation is done on the surface of the cornea. You then wear a bandage contact lens for a few days while the epithelium heals, and it takes several weeks to months for the eye to fully heal. If you have a stronger amount of correction needed, this can result in a permanent haze as the eye heals. Also, depending upon your personal healing properties, there is a risk that you may not get a perfectly healed epithelium. Vision will fluctuate over several weeks to months as the eye heals and stabilizes.
During LASIK, a "flap" is cut into to the cornea, typically at about 100 microns (used to be deeper). The flap is "peeled back" and the ablation is carried out deeper in the eye (in what is known as the stroma). The flap is then floated back in place, and you go home. Healing is virtually instant, as the next day you will see incredibly well.
The downside to LASIK is that the flap never fully heals, and is always a weak point in the eye. Furthermore, since the cornea has now been cut, all the nerves that tell your eye to tear have to re-connect across the interface, and even still, you will always have less connections. This is what causes dry eye post LASIK, and why it is imperative that if you have ANY dry eye issues pre op that LASIK will not be a good choice.
The upside to LASIK is that it effectively "fools" the eye into thinking there was no surgery, hence why recovery is so quick. There is absolutely no discomfort or pain.
The upside to PRK is that the eye retains more structural integrity, and there is no risk of dry eye. The downside is that the procedure is a little less accurate (though opinions vary on this from Dr. to Dr.) due to relying on the epithelium to heal as expected. Any shift in the epithelium's healing process can cause a mild refraction error.
The biggest downside to PRK is the healing process, and its associated discomfort.
If I were doing this today, I would look into LASEK, which is a modified form of PRK where they pull back the epithelium, ablate right on the cornea, and then put the epithelium back. Still not as convenient as LASIK, but hypothetically much less discomfort and faster healing than a traditional PRK and it retains the full integrity of the eye.
Hope this helps.
