• Laser eye surgery is the most commonly practiced procedure to correct vision problems caused by refractive errors, including myopia (near-sightedness), hyperopia (far-sightedness) and astigmatism (distorted vision when looking at objects at any distance).
• All of these conditions are caused by problems with the way the eye focuses an image on the retina, which is the light-sensitive layer at the back of the eye. A large part of the eye's ability to focus depends on the shape of the cornea, the clear front surface of the eye.
• During laser eye surgery, a surgeon uses a laser device to make permanent changes to the shape of the cornea. The laser used most often is the Excimer laser, which produces a beam of ultraviolet light to vaporize tissue. Surgically altering the shape of the cornea can correct mild to moderate refractive errors in most people.
• The two types of Excimer laser surgery performed commonly in Canada are PRK (Photo-Refractive Keractectomy), first introduced in the early nineties, and LASIK (Laser Assisted in situ Keratomileusis), introduced in the mid-nineties.
With PRK, the risks include:
• pain, ranging from moderate to severe, for the first few days;
• hazy vision during the healing process, which usually clears up within the first week after surgery; and
• regression, which in some cases can cause the eye to regress to its previous refractive error within about six months. If this happens, the patient may need a second operation (called an "enhancement") or may need to start wearing glasses or contacts again.
With LASIK, there is less post-operative pain. However, since this procedure involves cutting into the cornea, there is a greater risk of complications, including the following:
• dry eyes, which can range from mild to significant and can affect vision;
• poor quality of night vision due to halos and glare, which could affect your ability to drive at night; and
• a serious condition called corneal ectasia, which is a weakening and bulging of the cornea. Severe cases may need to be treated with a corneal transplant or implant.
Health Canada advises you are more likely to have a successful outcome with laser eye surgery if you:
Choose your eye surgeon carefully. The traditional approach is to get a referral from your own eye care professional.
Discuss the risks, benefits and your expectations with the surgeon. Read the "informed consent" form thoroughly. Ask questions. Make sure you are a suitable candidate for surgery before you decide to go ahead.
• Also, ask your surgeon for a copy of your pre-operative report, which should include information about your pre-operative vision, refraction readings and the shape of your cornea. Keep the report in a safe place for future reference.
• After surgery, you can reduce your risk of complications by participating fully in the follow-up care recommended by your eye surgeon