Until recently, if you were one of the millions of people with a refractive error, eyeglasses and contact lenses were the only options for correcting vision. But with the development of refractive surgery, some people with myopia (nearsightedness), hyperopia (farsightedness), or astigmatism (a cornea with unequal curves), can have their vision improved surgically.

Laser-assisted in situ keratomileusis (LASIK) is a refractive procedure that uses a laser to permanently reshape the cornea. The reshaped cornea helps focus light directly onto the retina to produce clearer vision.

LASIK is usually performed as an outpatient procedure using topical anesthesia with eyedrops. The procedure itself generally takes about 15 minutes. The surgeon creates a flap in the cornea with a special laser called a femtosecond laser. Tiny, quick pulses of laser light are applied to your cornea, creating microscopic bubbles at a specific depth and position within your cornea. Your ophthalmologist creates a flap in the cornea by gently separating the tissue where the bubbles have formed, and the flap is then folded back. The cool beam of a second laser, called an excimer laser, is used to remove a thin layer of corneal tissue. The flap is folded back to its normal position and sealed without sutures. The removal of corneal tissue permanently reshapes the cornea.

A clear shield protects the flap for the first day and night. Vision is usually slightly cloudy immediately after the procedure, but it clears rapidly, often within just a few hours. Your vision should be clear by the next day. Healing after surgery is often less painful than with other methods of refractive surgery, because the laser removes tissue from the inside of the cornea and not the surface. You will need to use antibiotic and steroid eyedrops several times a day for the first week, along with rewetting drops. After the first week, you will need to use only the rewetting eyedrops.

Some people experience poor night vision after LASIK. The surgery also may result in undercorrection or overcorrection, which can often be improved with a second surgery. More rare and serious complications include a dislocated flap, epithelial ingrowth, and inflammation or infection underneath the flap. Most complications can be managed without any loss of vision. Permanent vision loss is very rare.

The ideal candidate for LASIK has a stable refractive error, adequate corneal thickness and normal corneal shape, is free of eye disease, is at least 18 years old, and is willing to accept the potential risks, complications, and side effects of LASIK.

(c) 2007 The American Academy of Ophthalmology