�ٺ���Ƶ

LASIK, which stands for laser-assisted in situ keratomileusis, is the most widely performed surgery to correct refractive error. In this technique, lasers are used to make subtle changes to the shape of the cornea, which is the clear outermost part of the eye. When the cornea is reshaped correctly, it can refract light directly onto the retina, eliminating blurred vision.��

An eye surgeon performs LASIK in the office or at an eye center. Your doctor may offer you a sedative to help you relax.

First, the surgeon applies anesthetic eyedrops to numb the eyes. These take effect in about a minute. The surgeon uses a small instrument to hold the eyelids open.��

He or she then uses a laser or a small blade to separate the thin outer flap of the cornea from the rest of the eye. This part of the procedure may feel awkward, but it is not painful. While this occurs, you are asked to look at a small light to keep your eyes still.��

Then the surgeon uses a laser to reshape the exposed area of the cornea, so it bends, or refracts, light correctly. This reshaping is precise and based on the three-dimensional images of your cornea the doctor obtained during diagnostic corneal mapping.��

After the cornea has been reshaped, the surgeon replaces the outer flap and the procedure is finished. Your surgeon may place a clear contact lens that acts as a bandage on your eyes. The doctor removes these during a follow-up appointment a few days later.��

LASIK takes less than a half hour for both eyes, and you can return home after surgery. Your vision may be blurred for several hours, and you should arrange for someone to drive or escort you home after the procedure. Most people do not experience any pain after LASIK.��

Your surgeon sees you for a follow-up visit the day after surgery and schedules subsequent follow-up visits based on your healing progress and the type of refractive error that was corrected.

Your vision improves within one or two weeks. Most people have 20/20 vision for years after this procedure.

Surface ablation, commonly called PRK, or photorefractive keratectomy, is very similar to LASIK except that surgeons do not separate a thin flap of corneal tissue before reshaping the cornea with a laser. Surface ablation is an excellent alternative to LASIK for people who have abnormalities of the cornea, such as thinning or scarring, and may be better suited for people who have dry eye syndrome.��

In this procedure, the same laser that is used for LASIK is used to reshape the corneal surface directly. Surface ablation takes a few minutes per eye to complete—similar to the amount of time it takes to perform LASIK—and the treatment is also planned using a three-dimensional image of your cornea obtained during diagnosis. After the treatment is complete, the surgeon applies a clear bandage contact lens to protect your eyes while they heal.

You can return home after surgery. Because your vision may be blurred for several hours, you should arrange for transportation home.

Recovery from this procedure takes a bit longer than with LASIK, because new corneal cells must grow to cover the surface of the eye. You may feel a slight burn or ache in your eyes for a day or two after the procedure, and it may take up to a week for your vision to improve.

Most people are fully healed and have corrected vision within a couple of weeks. This procedure enables most people to have 20/20 vision for years.