Laser surgery for nearsightedness uses a laser to change the shape of the cornea . The goal is to have you see clearly without glasses or contact lenses or to be less dependent on them.

There are two main types:

• LASIK. LASIK makes a small flap in the cornea and removes some of the tissue underneath.
• Surface ablation (PRK, LASEK, and epi-LASIK). These three surgeries are very similar. PRK removes the top layer of the cornea, and then the cornea is reshaped. The layer grows back during the healing process. LASEK and epi-LASIK loosen the top layer of the cornea and push it out of the way. Then the cornea is reshaped and the surface replaced. It takes more time to heal from PRK, LASEK, and epi-LASIK than from LASIK, because the skin cells need to grow back.

PRK, LASEK, epi-LASIK, and LASIK have very similar long-term results. LASIK is the most common, but many people have one of the other types done instead because of the shape and condition of their eyes. LASEK may also be safer for people with certain lifestyles, such as professional athletes, police officers, and firefighters.

Other types of surgery for nearsightedness include radial keratotomy, corneal ring implants, and intraocular lens implants. Talk to your doctor to see if one of these is a better option for you.

Laser surgery gives most people 20/40 vision or better. Most doctors consider 20/40 vision a successful result. If your vision is at least 20/40, you can drive a car without glasses or contacts.

Most people who have laser surgery for nearsightedness are very happy with the results. Be sure to weigh the possible risks against the likely benefits.

Side effects and problems from surgery may vary slightly depending on which type of surgery you have. Most side effects either go away on their own or can be treated and fixed.

In general, side effects or problems from surgery may include:

• Cloudy vision.
• Dry eyes.
• Night vision problems.
• Glare or more sensitivity to bright light.
• Double vision.
• New astigmatism.
• Undercorrection or overcorrection. Undercorrection occurs when the eye remains somewhat nearsighted after surgery. Overcorrection makes the eye farsighted.
• Unstable vision.
• Reduction in best corrected vision, which is the best possible vision you can have using glasses or contact lenses.

Because laser surgery for nearsightedness has only been available since the 1990s, experts still don't know if there are problems that may occur many years later.

Serious problems that threaten vision are rare. These include infection, sores on the cornea, and higher pressure inside the eye, which can lead to glaucoma.

Laser surgery for nearsightedness is an elective procedure. This means that it's done for personal, not medical, reasons. You must decide for yourself whether the benefits of surgery outweigh the risks.

Before you have surgery, an ophthalmologist will examine you to see if you are a candidate for the surgery. You may not be able to have the surgery if:

• Your vision has not been stable for at least a year.
• You have certain problems in the cornea, such as keratoconus, keratitis, corneal edema, or thinning of the cornea.
• You have irregular astigmatism.
• You have moderate or severe dry eyes.
• You have an uncontrolled autoimmune or connective tissue disease.
• You are younger than 18.
• You are pregnant or breast-feeding. During pregnancy, women can have temporary changes in the way their eyes focus.

You may not want this surgery if it could affect your job. Some employers don't allow certain workers to have this surgery because of the slight risk that it can cause permanent problems. Aircraft pilots, for example, should check with their employers before deciding to have this surgery.