Laser vision surgery is a popular treatment for vision problems. It can reduce or eliminate the need for eyeglasses or contact lenses.

Laser procedures can help correct refractive errors. These are problems caused by an imperfectly shaped cornea and the length of the eye. The cornea is the clear part on the front of the eye that focuses light. Refractive errors cause light from an object not to be focused on the retina. This causes a blurred image. Refractive errors often occur in otherwise healthy eyes.

These are the four basic types of refractive errors:

• Nearsightedness (myopia). Close objects appear sharp, but those in the distance are blurred. The eye is longer than normal from front to back or the cornea is curved too much. Images focus in front of the retina.
• Farsightedness (hyperopia). Distant objects can be seen clearly, but objects up close are blurred. The eye is shorter than normal or the cornea is too flat. Images focus behind the retina.
• Astigmatism. Objects are blurred at any distance. The cornea, lens, or both are shaped so that images aren't focused sharply on the retina.
• Presbyopia or aging eye. The eye loses its ability to change focus because of the natural aging process. This often occurs between ages 40 and 50. Refractive surgery can't correct this problem. It can make distance vision clearer, but it may make near vision worse.

• LASIK (laser in situ keratomileusis). This makes up 90% to 95% of all laser vision correction surgery. It has the broadest range of uses. LASIK permanently changes the shape of the cornea. Sometimes a knife called a microkeratome is used to cut a hinged flap in the cornea. This flap may also be created with a special laser designed for this procedure. The flap is folded back, revealing the middle section of the cornea (the stroma). Pulses from a computer-controlled excimer laser remove a part of the stroma and the flap is replaced. IntraLase LASIK uses a laser to create the flap. This results in a thinner flap. It allows for higher prescriptions to be corrected.
• PRK (photorefractive keratectomy). This method uses a laser to remove the surface of the cornea and reshape it. PRK gently reshapes the cornea by removing tiny amounts of tissue from the outer surface. Recovery takes longer than it does with LASIK.
• LASEK (laser epithelial keratomileusis). This procedure combines LASIK and PRK methods. It may be used for people who can't have LASIK. The surface of the cornea is loosened with an alcohol solution and moved aside before a laser reshapes the cornea. No flap is cut.
• LTK (laser thermal keratoplasty). This is a less invasive laser procedure to correct farsightedness and astigmatism. LTK uses heat to reshape the cornea. The advantage of LTK is that it's a "no-touch" procedure. This means there's little chance of infection or loss of vision. This method is being done less often than in the past.

Health insurers rarely pay for this type of surgery, which is considered for looks only and not medically necessary. Prices vary, from $300 to $2,400 per eye. But experts warn that cost shouldn't be your only concern.

Laser surgery may not be right for you. These are factors that show you are not a good candidate:

• You aren't a risk-taker. Some people do have complications. No long-term data are available for current procedures.
• It could affect your career. Check with your employer, military service, or professional organization, before having surgery. Some jobs ban certain refractive procedures.
• You needed a change in your contact lens or eyeglass prescription in the past year. This is called refractive instability. You are more likely to have refractive instability if you:
  • Are in your early 20s or younger
  • Have changing hormones because of a disease, such as diabetes
  • Are a woman who is pregnant or breastfeeding
  • Are taking medicines, such as steroids
• You have a disease or are on medicines that may affect wound healing. Illnesses include autoimmune diseases, such as rheumatoid arthritis, HIV, and diabetes. Medicines include retinoic acid and steroids.
• You have an eye disease or an immediate family member has a corneal eye disease.
• You play contact sports like boxing, wrestling, or martial arts. Blows to the face and eyes are common with these sports.
• You aren't an adult. No lasers are approved for children or teens younger than 18.

Besides the illnesses listed above, other diseases may negatively affect the outcome of LASIK surgery:

• Herpes simplex or shingles (herpes zoster) around the eye area
• Glaucoma, ocular hypertension, or you are at risk for glaucoma
• Eye injuries or past eye surgeries
• Keratoconus, a thinning disorder of the cornea

These are other risk factors that may affect the outcome of your surgery:

• Large pupils. Younger people and people on certain medicines may have large pupils in dim light. This can cause glare, halos, starbursts, and double vision after surgery. The symptoms may be severe enough to interfere with normal activities, such as driving.
• Thin corneas. Refractive surgery done on a cornea that is too thin may lead to blindness.
• Past refractive surgery. Talk with your doctor if you've had RK, PRK, LASIK or another refractive procedure. Additional surgery may not be advised.
• Dry eyes. LASIK can make this condition worse.
• Undercorrection or overcorrection can occur if too little or too much tissue is removed.
• Astigmatism can occur if an uneven amount of tissue is removed.
• Glares, halos, or double vision can result.

Only ophthalmologists are permitted to do LASIK. Ask your eye doctor for a referral to an ophthalmologist who does LASIK. You can also visit the American Academy of Ophthalmology (AAO) website , which offers a list of its members who do LASIK. About 19 out of 20 ophthalmologists are AAO members. Ask your surgeon the following questions:

• How long have you been doing LASIK surgery?
• How much experience do you have with the LASIK procedure?
• How do you define success? What's your success rate?
• How many and what types of complications have your patients had?
• What is your postsurgical infection rate?
• What is the chance for me (with my correction) to achieve 20/20 vision?
• How many of your patients have achieved 20/20 or 20/40 vision?
• How many patients return for enhancements?
• Which laser will you be using for my surgery?
• What's involved in after-surgery care?

If you are uncomfortable asking these questions, bring a friend or family member with you who will ask them for you. It is vital to your decision about surgery, and your safety, that you have this information.

Make sure your surgeon is using a laser approved by the FDA. The FDA has approved five lasers for LASIK. They are made by VISX, Summit, Bausch and Lomb, Nidek, and ATC.

Many people don't have 20/20 vision after surgery. But most are 20/40 or better. About 8% to 10% need an added procedure known as an enhancement. Some need eyeglasses or contact lenses to make up for overcorrection or undercorrection.

Possible complications include:

• Night glare
• Small gray or white spots in the cornea (corneal infiltrates)
• Ripples
• Infection
• Vision goes back to your original prescription (regression)
• Undercorrection
• Images are not clear or sharp (loss of visual acuity)
• Dry eyes
• Trouble fitting contact lenses for additional correction
• Need for retreatment

The complication rate is around 10%.

If you're a good candidate for a LASIK procedure, have realistic expectations, and choose the right surgeon, chances are very good that you will do well.