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Marin Eye Care: LASIK Eye Surgery

What is LASIK?

The eye and vision errors

 The cornea is a part of the eye that helps focus light to create an image on the retina. It works in much the same way that the lens of a camera focuses light to create an image on film. The bending and focusing of light is also known as refraction. Usually the shape of the cornea and the eye are not perfect and the image on the retina is out-of-focus (blurred) or distorted. These imperfections in the focusing power of the eye are called refractive errors. There are three primary types of refractive errors: myopia, hyperopia and astigmatism. Persons with myopia, or nearsightedness, have more difficulty seeing distant objects as clearly as near objects.  Persons with hyperopia, or farsightedness,  have more difficulty seeing near objects as clearly as distant objects.  Astigmatism is a distortion of the image on the retina caused by irregularities in the cornea or lens of the eye. Combinations of myopia and astigmatism or hyperopia and astigmatism are common. Glasses or contact lenses are designed to compensate for the eye's imperfections. Surgical procedures aimed at improving the focusing power of the eye are called refractive surgery. In LASIK surgery, precise and controlled removal of corneal tissue by a special laser reshapes the cornea changing its focusing power.

Other types of refractive surgery

Another type of refractive surgery is thermokeratoplasty in which heat is used to reshape the cornea. The source of the heat can be a laser, but it is a different kind of laser than is used for LASIK and PRK. Other refractive devices include corneal ring segments that are inserted into the stroma and special contact lenses that temporarily reshape the cornea (orthokeratology).

You may want to discuss some surgical alternatives to Lasik with your eye doctor:

• Photorefractive keratectomy (PRK) is a laser procedure used to reduce myopia, hyperopia and astigmatism without creating a corneal flap.
• Astigmatic keratotomy (AK) is an incisional procedure to reduce astigmatism.
• Intrastromal corneal rings are clear, thin, polymer inlays placed on the eye to correct low myopia only.

Risks and Possible Complications

• Over- or under-correction. These problems can often be improved with glasses, contact lenses and enhancements.
• Corneal scarring, irregular astigmatism (permanent warping of the cornea), and an inability to wear contact lenses.
• Corneal infection.
• "Loss of best corrected visual acuity" - that is, you would not be able to see as well after surgery, even with glasses or contacts, as you did with glasses or contacts before surgery.
• A decrease in contrast sensitivity, "crispness," or sharpness. That means that even though you may have 20/20 vision, objects may appear fuzzy or grayish.
• Problems with night driving that may require glasses.
• Flap problems, including: irregular flaps, incomplete flaps, flaps cut off entirely, and ingrowth of cells under the flap.

The following side effects are possible, but usually disappear over time. In rare situations, they may be permanent.

• Discomfort or pain
• Hazy or blurry vision
• Scratchiness
• Dryness
• Glare
• Haloes or starbursts around lights
• Light sensitivity
• Small pink or red patches on the white of the eye