A laser that vaporizes animal tissue "a la Flash Gordon's ray gun" may someday enable nearsighted people to throw away their glasses or contact lenses, a researcher said.
"Our ultimate hope is that with a 20-second laser treatment you may never need glasses again, but we are only in the infancy of human trials," Dr. Herbert Kaufman, chairman of the Department of Ophthalmology at Louisiana State University Eye Center in New Orleans, said Wednesday."We have finished the animal studies and are far enough along to say research with the Excimer laser that vaporizes tissue a la Flash Gordon's ray gun is particularly exciting and that it looks like the technique works well," Kaufman, professor of pharmacology and experimental therapeutics, said in an interview.
About 140 million Americans wear corrective lenses, according to statistics of the American Optometric Association, and 25 million of them suffer from myopia, or nearsightedness, in which visual clarity decreases with distance.
The technique has been tested on 70 monkeys during the past year, but has been tried on only one person. Kaufman and the manufacturer of the laser, VISX Inc. of Sunnyvale, Calif., recently petitioned the Food and Drug Administration to allow expanded human studies.
Most myopic people have an eye somewhat longer than normal from front to back, and the laser corrects nearsightedness in the same fashion as contact lenses or the surgical procedure radial keratotomy - by flattening the front curvature of the cornea.
Radial keratotomy is an operation in which tiny shallow cuts are made in the cornea.
The cornea is a transparent, gelatinous cover one-fiftieth of an inch thick that sits over the pupil like a crystal over a watch face and plays a key role in bending light to focus images on the retina at the back of the eye.
"The short ultraviolet light of the laser has such tremendous energy, it tears apart atoms in the corneal tissue without heat or burning," Kaufman said at a three-day international ophthalmology conference sponsored by the University of California, San Francisco, School of Medicine and held in conjunction with the opening of a new vision center at the school.
Repeated pulses of the light are beamed through a computer-controlled shutter-like device with such precision that "the tissue vaporizes in segments finer than a human hair," he said.
The laser shapes a bowl-like lens on the cornea, changing the focus at the front of the eye and correcting the myopia, Kaufman said.
The scientists were able to make the monkeys, which had normal vision, farsighted to the exact degree desired. The monkeys' vision was tested by having them identify objects from varying distances.
"We want to make nearsighted humans farsighted enough to compensate for their myopia," Kaufman said. "It seems we have the control needed to accomplish this without damaging the eye."
If all goes well, the laser may eventually not only help nearsightedness, Kaufman said, but also benefit patients whose vision is impaired by farsightedness or an astigmatism.