| LASER REFRACTIVE SURGERY - The Laser and the Surgery
The excimer laser.
The excimer laser was developed in 1976 by IBM to etch computer microchips. It was first used for the eyes in Europe in 1988. A laser contains a device to create light in a similar manner as a light bulb, but more sophisticated and precise. With an excimer laser, when an electric current is passed through a tube containing a special gas (argon fluoride), a reaction occurs that produces ultraviolet light energy. The direction, focal point, intensity and release of the light from the tube are precisely controlled by the surgeon and a computer. The light passes through a system of mirrors that result in all the light rays traveling in one direction (coherent light), and focuses the energy to a fine point. As the light gets closer to the focal point, the energy becomes more concentrated and the beam gains strength. Laser light reaches its maximum strength at the focal point, the point where all the rays converge. The strength of the beam rapidly diminishes after passing the focal point, and can no longer affect adjacent tissue in the eye , making it a very safe procedure.
The excimer laser is so precise that each pulse only removes 39 millionths of an inch of tissue in 12 billionths of a second. It would take 200 pulses to just cut through a human strand of hair!
The LASIK procedure.
A special instrument (a microkeratome) is applied to the cornea, creating a thin flap of corneal tissue. The flap remains attached to the eye at one end. Next, the laser is used to reshape the cornea. The flap is then put back into position and the procedure is complete.
For Myopia, either a narrow diameter beam that slowly expands
as shown above, or a scanning beam is used to produce
a tiny lens-shaped disc on the surface of the cornea.
LASIK is performed on an outpatient basis using an eye drop anesthetic to numb the eye for painless surgery. It normally takes less than 30 minutes and the patient leaves shortly after the procedure. An eye patch may be placed on the eye for temporary protection and to keep you from rubbing your eye in your sleep. Medication drops are used for pain relief, to prevent infection and promote healing. After LASIK, patients usually return to their normal lifestyle quickly with very few restrictions during the short healing period. "Functional" vision is usually obtained within 1 to 3 days.
Am I a candidate for laser refractive surgery?
You are a good candidate if . . .
- You are nearsighted (myopic), farsighted (hyperopic), or have astigmatism.
- Your eyes are in good health.
- Your vision is stable and you are at least 18 years old.
- You are in good general health.
- Corrective lenses (contact, eyeglasses) interfere with your occupation or the lifestyle you want to live
- You feel that you look better without glasses.
- You are contact lens intolerant.
- Your occupation does not allow you to wear contact lenses.
- You are tired of the frustrations associated with always having to wear eyeglasses or contact lenses.
What results can be expected?
Vision correction surgery has corrected or improved the vision of millions of people around the world. Studies show that over 95% of patients who have had this surgery are able to pass a standard driver's license eye exam (20/40 visual acuity or better) without corrective lenses. Although perfect vision after the surgery may be a likely result, not every patient will be able to achieve the ideal 20/20 vision. The results are also dependent on how bad one's initial prescription is; the worse it is to begin with, the more difficult it is to achieve optimal vision. An enhancement, or re treatment, may also be needed if less than optimal results are obtained after the initial treatment. The goal of vision correction surgery is to provide functional vision, and reduce your dependency on glasses or contact lenses. Since perfect vision is not always achievable, some patients may desire to wear corrective lenses after surgery for some activities. Refractive surgery is a choice you will make only after a complete medical eye examination and extensive counseling on the benefits and risks of the procedure.
Will I need glasses after the surgery if I'm over 40?
People who have presbyopia (see "I'm over 40 and I can't read well up close, Why?") and who choose vision correction surgery will probably need glasses for reading. However, by making a slight adjustment to the desired outcome of the procedure that corrects one eye for the distance and leaves the other eye corrected for reading, the dependency on reading glasses can be reduced. This technique is called monovision, and is seen commonly with contact lenses. There are some major limitations to this method, but again, it can work well for many people who are aware of the drawbacks. Dr. Vosseteig will review this option in detail with you before choosing this method.
Laser Questions & Answers | The Lasik Surgery Procedure | Alternatives to Lasik
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