LASIK is a procedure that reshapes the cornea to improve vision.

LASIK can treat nearsightedness (myopia), farsightedness (hyperopia), and astigmatism. These are conditions that require the use of glasses and contact lenses for clear vision. With some exceptions, LASIK generally treats myopia between -0.5 and -10 diopters, hyperopia between +0.5 and +6.0 diopters, and astigmatism between 0.5 and 6.0 diopters.

Patients who have had previous eye surgery may qualify for LASIK. LASIK can be performed after previous radial keratotomy (RK), photorefractive keratotomy (PRK), and cataract surgery. LASIK can be performed on "lazy eyes" and eyes with nystagmus.

Alternative Procedures to LASIK

For lower degrees of nearsightedness (less than -3.00 diopters), Intacs-micro precision implants placed within the cornea, which sharpens vision by flattening the cornea-may be an option. Intacs micro-prescription inserts are removable and exchangeable, and this procedure avoids operating in the center of the cornea. Intacs can be performed in patients with keratoconus as well.

For lower degrees of farsightedness (less than +2.50 diopters), LTK (Laser Thermokeratoplasty)-a three-second, no-touch laser procedure that uses heat spots to steepen the cornea and refocus light rays-may be an option. LTK improves vision in patients with farsightedness and presbyopia.

For the same range of LASIK, No-Cut LASEK is an alternative to LASIK. The difference is that there is no flap of the stroma of the cornea. The surface skin is loosened with a solution and moved to the side. The top of the cornea is reshaped with the same laser used in LASIK. The skin is replaced, thereby covering the cornea. The recovery of vision is slower, but the end result can be predicted to be similar to LASIK. This is an alternative for patients uncomfortable with the flap aspect of LASIK.

Even though glasses or contact lens prescriptions may fall within the diopter ranges above, there are conditions that make these procedures inappropriate until the conditions are treated or resolved. These include:

For purposes of this CONSUMER REPORT, LASIK will be emphasized as it represents the majority of vision correction procedures performed.