Health Talk: LASIK Surgery
Sometimes, all it takes to fix eyesight is a laser. For people with poor vision, LASIK surgery may permanently and dramatically correct vision. LASIK stands for Laser-Assisted In Situ Keratomileusis, which basically means surgery on your eye with a laser. “In situ” means in place and “Kerat” in medical terms refers to the cornea of the eye.
Most people have a number of misconceptions about the causes of poor vision. Watching too much TV isn’t a cause of poor vision; it is mostly the cornea’s fault.
The cornea is the front, transparent part of the eye. The cornea, which focuses light, is critical to the function of the eye. To that end, the eye works like a camera: Light enters the eye from the cornea to the lens, where it is further fine-tuned and focused to converge at a point on the retina. The cornea does most of the focusing. The lens’s job is to fine tune the light for focusing, and the retina’s job is to capture and transmit the signals to the brain, where they are interpreted into pictures.
If the cornea is bumpy or messy with bits of corneal tissue, light will refract unevenly, causing pictures to appear blurry. If light rays do not converge at the same point on the retina, a blurry image is formed. If the light rays fall on a point beyond the retina, the condition is called far-sightedness. When rays converge at a point before the retina, the person has near-sightedness. Glasses help correct these disorders by assisting in focusing the light. With LASIK surgery, however, one does not need to use glasses at all.
LASIK surgery uses laser beams to permanently improve the refractive power of the cornea. The procedure is possible because of the unique structure of the cornea. The cornea is built in layers, and surgery is done in the upper layers. The cornea gets its nutrients from the aqueous humor — the jelly-like substances inside the eye cavity. Hence, there are no blood vessels in the cornea, and there is little risk of bleeding.
LASIK surgery has become common for a number of reasons. Laser beams are very precise and can work within nanometers of the eye. The surgery is a same-day procedure and does not require hospitalization or general anesthesia. Also, some insurance companies help cover the cost of surgery, as it improves a person’s life. The surgery costs anywhere from $500 to $1500 for one eye.
People undergoing LASIK surgery are asked to stop wearing contact lenses a week before surgery. The procedure begins by using anesthetic drops to numb the eye. The surgeon makes a cut on the outer layer of the cornea using a special knife called a microkeratome to get to the inner layer. A good analogy would be to imagine someone peeling the skin of a potato with a very thin knife to get to the flesh. However, the surgeon folds the “peel” of the cornea, so it is like a hinged door.
The next step is reshaping the cornea using a computer-controlled laser which uses cool, ultraviolet beams to remove bits of tissue. The laser is activated by a foot pedal at the surgery table. The laser moves the bonds of the corneal tissue and smooths out the surface of the cornea. Next, the surgeon finishes the surgery by folding back the “peel” of the cornea. The numbing drops wear off in a couple of hours, and there is rarely any bleeding. If everything goes well, the patient will wake up with perfectly clear vision the next morning. Patients usually go back to their normal routine within days without glasses.
However, like all surgeries, the procedure is not always perfect. During surgery, the corneal flap can be lost. The surgery can also cause the patients’ vision to worsen, or in some extreme cases, people can lose their sight.
LASIK is not for people who have other eye disorders, and it cannot reverse the normal aging of the cornea.
The FDA website quotes optometrist Stephen Crawford from Virginia: “With LASIK, the skill of the surgeon is important because he’ll be making an incision.” Crawford urges people to find qualified, experienced doctors to perform this surgery. “You’ll want someone who’s done a number of LASIK procedures since this is a surgeon-dependent operation.”