Laser-assisted in situ keratomileusis: A kind of laser eye surgery designed to change the shape of the cornea to eliminate or reduce the need for glasses and contact lenses in cases of severe myopia (nearsightedness). The procedure is best known as LASIK, an acronym for laser-assisted in situ keratomileusis.
Before LASIK, the most common form of laser eye surgery was a treatment called PRK which involved scraping away the surface cells of the cornea before reshaping it with the laser. Unfortunately, the healing process after PRK tends to be very painful and can take weeks. Furthermore, both eyes cannot be treated at the same time and the patient must wait several months between treatments to allow each eye to recover sufficiently.
LASIK is an ambulatory procedure done in an ophthalmology office or clinic. Numbing eye drops are used. The eyelids are held open so that there is no interference with the laser. The ophthalmologist creates an ultrathin flap on the front of the eye with a precise automated instrument. The flap is gently lifted and the preprogrammed laser then reshapes the inner cornea to refocus the eye. The flap is repositioned and holds itself in place, healing naturally without the need for any stitches. The laser pulses last on the average between 30 and 60 seconds. In all, LASIK takes about 20 minutes to do both eyes. The procedure is without much pain and recovery is quick.
One may experience some mild discomfort and watering of the eyes after treatment. This varies from person to person but has been likened to the sensation of having worn contact lenses for too long. The risks associated with LASIK also include a small but real risk of an infection in the eye. No eye patch need be worn after LASIK.
LASIK is now coming into use also to treat hyperopia (farsightedness) and astigmatism. LASIK does not treat or prevent age-related long-sight (presbyopia), which is due to the decreasing flexibility of the eye's lens that almost all of us experience as we approach our fifties and need to wear reading glasses.
Women considering LASIK need to know that hormonal changes in pregnancy affect the cornea's shape and density and can complicate both the healing process and the success of LASIK. Women who plan to become pregnant within 6 months of LASIK surgery should not have the procedure done.