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ShareJanuary 1, 2007 — Ophthalmologists have developed new software that analyzes the shape of the patient's cornea during the LASIK procedure and automatically adjusts the laser based on that cornea's unique anomalies. The technology allows LASIK to correct new, more subtle types of vision flaws beyond farsightedness, nearsightedness, and astigmatism.
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ROCHESTER, N.Y. -- In just a few minutes ... LASIK eye surgery has Kelli Tette, saying goodbye to glasses! "I can see so much better than I ever did even with my glasses or contacts on," she says.
It's a popular comment from many patients. But sometimes eye imperfections cause slightly farsighted or nearsighted vision even after surgery. Now, a new system used with LASIK creates better results.
"The University of Rochester Nomogram is a system that takes into account these subtler irregularities of vision and corrects them out," Scott MacRae, an ophthalmologist at University of Rochester in N.Y., tells DBIS.
Ophthalmologists say 20 percent of patients are still slightly farsighted after surgery. Using the new system, that number drops to 2 percent.
Dr. MacRae says, "The biggest benefit to patients with the Nomogram is they're less likely to need a retreatment after the procedure."
Patients undergo a test to find flaws within the eyes. That information is fed into the new system using computers and then helps control and adjust the laser beam during surgery to fix imperfections for a picture-perfect result.
"It saves us time. It saves the patient time," Dr. MacRae says. "But more importantly, the patients see well right from the start."
The system caught Tette's eye defects before surgery. "It's definitely changed my life," she says. And today, Tette sees better than 20/20 at about 20/15.
Generally, anyone with advanced rheumatoid arthritis, keratoconus, or active herpes simplex of the cornea may not be good a candidate for LASIK.
BACKGROUND: Opthalmologists at the University of Rochester Medical Center, in New York state, have developed a formula that slashes by nearly two-thirds the likelihood that patients will need repeat visits to an eye surgeon to adjust their vision after their initial LASIK visit. That's because the formula makes it more likely that surgeons will get it right the first time. The new software controls how the laser beam used in the surgery travels around the surface of the cornea during the procedure enabling the surgeon to sculpt the cornea into just the right shape so that it produces as flawless an image as possible. Everyone's eyes are slightly different. By taking into account the unique anomalies in each person's eye, the formula predicts which patients are most likely to be slightly far-sighted after a LASIK procedure, and adjusts the laser to avoid that outcome. This reduces the need for repeat treatments in patients from about 8 percent to 3 percent.
LASING A PATH: Laser eye surgery uses a pulsed, tightly focused beam of light to vaporize a tiny portion of the cornea to reshape it. The surgeon creates a thin, circular flap in the cornea with a laser, folds it back out of the way, then removes some of the cornea tissue underneath, also by laser. The flap is then laid back into place over the area where the tissue was removed. By controlling the size, position and number of laser pulses, the surgeon can precisely control how much of the cornea is removed. Reshaping the cornea changes the focal point of the eye, resulting in corrected vision. A LASIK procedure generally lasts 15 to 60 seconds, during which time the laser beam hits the cornea 50 times per second. So the timing and aim must be as precise as possible.
HOW LASERS WORK: "Laser" is an acronym for Light Amplification by Stimulated Emission of Radiation. It describes any device that creates and amplifies a narrow, focused beam of light whose photons are all traveling in the same direction, rather than emitting every which way at once. Laser light contains only one specific color, or wavelength. Lasers can be configured to emit many different colors in the spectrum, but each laser can emit only that one color. Because every photon is traveling in the same direction, the light is tightly focused into a concentrated beam, unlike the light emitted from a flashlight, where the atoms release their photons randomly in all directions. There are many different types of laser, but all of them have a cavity containing a "lasing" medium: either a crystal such as ruby or garnet, or a gas or liquid. There are two mirrors on either end of the cavity, one of which is half-silvered, meaning that it will reflect some light and let some light through. (The light that passes through is the emitted laser light.) In a laser, the atoms or molecules of the lasing medium are "pumped" by applying intense flashes of light or electricity. The end result is a sudden burst of light as all the atoms discharge in a rapid chain reaction.
The American Association of Physicists in Medicine contributed to the information contained in the TV portion of this report.
Editor's Note: This article is not intended to provide medical advice, diagnosis or treatment.
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