# Monday, October 5, 2009
                 

Every year, thousands of Canadians contemplate laser eye surgery in order to correct their vision. This surgery is done in anticipation of the person no longer being required to use contact lenses and/or prescription glasses in order to have better vision. Canadians who are contemplating laser surgery should be well informed of not the benefits of these procedures, but also the risks.

Laser eye surgery is most commonly used to correct vision problems such as:

  • Myopia, also known as near-sightedness;
  • Hyperopia: also known as far-sightedness;
  • Astigmatism: when vision is distorted when looking at objects at any distance;
  • Presbyopia: when the person is unable to focus on nearby objects.

All of these vision conditions are caused by problems with the eye focuses an image on the retina (the light-sensitive layer at the back of the eye). A large part of the eye’s ability to focus is dependent on the shape of the cornea (the clear front surface of the eye). A surgeon will use a laser device to make permanent changes to the shape of the cornea. Most often used is the Excimer laser, which produces a ultraviolet light beam which vaporizes tissue, thus altering the shape of the cornea. This usually corrects mild to moderate refractive errors in the eye.

There are several types of laser eye surgery that are commonly performed in Canada:

  1. PRK (Photo-Refractive Keractectomy): the outer layer of the cornea is removed with a surgical blade or blunt instrument. A computer-guided laser beam is then used to vaporize tiny amounts of tissue that are under the surface of the cornea. This procedure removes just enough tissue in order to reshape the cornea in a way that the vision is now corrected. The healing process of this procedure is usually completed within one week.
  2. LASIK (Laser Assisted in situ Keratomileusis): This procedure is more complicated than PRK. A flap is cut in the cornea with either a sharp blade or a laser. The flap is then lifted and a computer-guided laser removed specific calculated amounts of tissue from the inside layers of the cornea. The flap is then put back. Wavefront technology may be used in this procedure, wherein a detailed map of the eye is produced. The healing time for this procedure is generally less than the time for PRK.
  3. LASEK (Laser Epithelial Keratomileusis): This procedure is a variation of both PRK and LASIK. The outer layer of the cornea is cut and then alcohol is used to loosen and lift it in a single layer. A laser beam is then directed at the tissue under the epithelium. This procedure is best suited to people who have vision problems that require minor correction; the healing period is usually two weeks. As with any surgical procedure, there is a risk taken (though quite small), that complications can arise. Each certain procedure does carry with it a small percentage of complications. For those contemplating PRK, the risks include: • Moderate to severe pain for the first several days; • Hazy vision during the healing; this generally will clear within the first week after the surgical procedure; • Regression. In some cases the eye can regress to its previous refractive error, this usually will occur during the first 6 months. In these cases the person may need a second (enhancement) surgery, or may have to once again wear corrective eyewear or contact lenses.

See our next blog article for the conclusion about laser eye surgery.

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