The LASIK procedure is irreversible. The long term complications of the surgery are still to be fully documented. However the procedure is safe and many advancements have taken place since its invention
The incidence of unresolved complications in patients six months after the LASIK surgery is 3% to 6%. Some of the frequently observed complications are as follows:

Over or under corrections

Sensitivity to light

Dry eyes

Fluctuations in visual acuity

Double vision

Presence of wrinkles or debris under the corneal flap

Induced astigmatism

Erosion of the epithelium

Posterior vitreous detachment

Hole in the macula
In an interesting review it was found that the patients who were dissatisfied with the LASIK Surgical procedure were the ones who had unexpected expectations from the procedure rather than faulty surgery(4).
"If the surgeon tells the patients they will have perfect vision afterwards and they will throw away their glasses, that raises unduly high expectations" David Gartry, Laser eye surgeon, UK