How it's done

There are two main types of laser eye surgery:

• Surface treatment (also known as PRK, LASEK or EpiLASIK)
  
  
• Treatment performed under the corneal flap (LASIK).

The best type of surgery for you depends on how bad your eyesight is, the thickness of your cornea, and your lifestyle.

Surface treatments

Surface laser or PRK (photorefractive keratectomy) was the first technique available. A portion of the top layer of the cornea is scraped off and the laser reshapes the surface of the cornea.

PRK is a more simple procedure than LASIK (see below). PRK is more suited for correcting lower degrees of short-sightedness and astigmatism, or if you have a thin cornea. It may also be recommended if you play high contact sports, such as rugby league, because there's no corneal flap to heal.

LASEK (laser assisted subepithelial keratomileusis) and EpiLASIK (using a finer tool) are based on PRK. The top layer of the cornea is pushed aside during surgery and replaced afterwards to preserve more corneal tissue.

In LASEK the outer layer of the cornea is loosened with a weak alcohol solution, while in EpiLASIK the skin is removed with an electromechanical device. Both procedures still involve laser surgery on the surface of the cornea.

Recovery from PRK, LASEK and EpiLASIK can be uncomfortable and will take about a week. There's a higher risk of visual problems, such as corneal haze or blurry vision.

Inside-the-cornea techniques

The most commonly performed surgery is LASIK (laser in-situ keratomileusis). A tiny flap is created in the outer layer of the cornea, so that a laser can reshape the tissue underneath. The flap is placed back over the treated cornea and it sticks naturally.

The original LASIK procedure used a miniature scalpel (called a microkeratome) to cut the flap. The flap was left attached to the cornea by a "hinge". The bed beneath the flap was reshaped using the laser and the flap replaced.

LASIK is less painful and has a lower incidence of post-operative haze and regression than surface treatments. Recovery is rapid (around 12 hours). LASIK is more suited to severely short- or long-sighted people. But there's a small risk of surgical complications from the surgical blade.

In newer procedures a thinner flap is created with a computer-guided laser, often called by its brand name IntraLase. With "blade-free" IntraLase LASIK there's a lower risk of infection and a lower risk of cutting a poor-quality irregular flap.

What's the best method?

Unfortunately experts disagree over whether LASIK or surface techniques are best.

Dr David Prendergast, from Auckland Eye, Dr Tony Morris, from the Eye Institute, and Dr David Kent, from the Fendalton Eye Clinic, perform IntraLase LASIK. Dr Prendergast and Dr Morris believe there's no question IntraLase LASIK is the safest method.

Dr Kent said: "IntraLase is a significant safety advance because the worst risk with LASIK was the problems with the microkeratome blade. This risk is removed with IntraLase."

Although Dr Andrew Logan from the Wellington Eye Centre has had LASIK surgery, his centre has stopped doing the procedure because of the risk of complications from cutting the corneal flap. He believes EpiLASIK has excellent safety results and these are as good as, or better, than PRK and LASIK.

Some optometrists share Dr Logan's concern. A Wellington optometrist told us he was concerned about any procedure that cuts the corneal flap.

People who have had laser eye surgery may have restricted their options for detecting and treating glaucoma.

People need to be aware that as they get older their vision may naturally deteriorate and it's likely they will need reading glasses.

The Royal Australian and New Zealand College of Ophthalmologists considers that PRK, LASEK, EpiLASIK and LASIK are acceptable surgical procedures for the correction of refractive errors such as short-sightedness, long-sightedness, and astigmatism.