ARA) - Traditional LASIK has taken the public by storm as a way to correct nearsightedness, farsightedness and the blurriness called astigmatism. But the National Aeronautics and Space Agency (NASA) was not convinced until recently that LASIK (a form of refractive surgery) was for anyone with space aspirations. All that changed last fall when NASA announced it would now accept astronaut applicants from people who had undergone LASIK.
Although it had taken NASA some time to come around to the idea, refractive surgery is actually a natural fit for astronauts, according to Steven C. Schallhorn, M.D., chief medical director of Optical Express and in private practice in San Diego and consultant for NASA for ten years. “Glasses and contact lenses are not conducive to the aerospace environment,” Dr. Schallhorn says. “For instance, your glasses can “float” out of reach, and cleaning contacts with no gravity is much more laborious. In addition, there have been contact lens-related problems in space.”
Early LASIK countdowns
Despite the broad popular appeal, NASA was reluctant to go forward with refractive surgery before now. At the start, the two principal concerns shared by NASA and the military were the stability of the LASIK flap and the resulting quality-of-vision after the procedure. LASIK involves making a surgical incision to create a flap on the surface of the clear outer part of the eye called the cornea. The flap is then folded back to allow a laser to correct the patient’s vision and laid back into place, where it re-adheres to the cornea.
The Navy launched a series of internal studies to address how the LASIK flap would fare under extreme conditions. “We conducted a number of studies,” Dr. Schallhorn says, “and they concluded that there were no effects on LASIK.” While the Navy initiated a PRK-based program for aviators, NASA continued to hold back. “They were interested in the whole package,” Dr. Schallhorn says. “They wanted to know if LASIK would be satisfactory also.”
Into the final frontier
Advances in LASIK technology have been a continuing process since its introduction. One of the most important advances was “wavefront guidance.” The technology uses a beam of laser light that has been reflected off the back of a patient’s eye. Imperfections in the patient’s eye distort the beam. The beam is analyzed and used to make a treatment map that guides the laser as it reshapes the eye. Thus the term, “Wavefront-guided LASIK.”
Spurred by such innovations, NASA decided to take another look at LASIK. “We studied wavefront-guided LASIK and found that it was clearly superior to conventional procedures,” Dr. Schallhorn says. “We then looked at the LASIK flaps created by a laser and compared them to flaps created using a special surgical blade and found that the laser flap was superior in a number of important areas.” When the two new approaches were paired, investigators found that LASIK resulted in vision as good as that made by PRK.
Investigators led by Dr. Schallhorn found that advanced LASIK, meaning the using laser created flaps combined with wavefront-guided treatment, fared well in night-driving simulations. Armed with these results, Dr. Schallhorn approached leaders from the Navy aeromedical community, who had been waiting for the project results. “After the studies were complete and analyzed, my recommendation was that advanced LASIK was ready for the aviator,” Dr. Schallhorn says.
He sees the NASA approval of LASIK as having important implications. “Ten years ago, nearsighted individuals could not become pilots or astronauts,” Dr. Schallhorn says. “What laser vision correction means is that these people can now have their aspirations come true.”
It is also significant in a much broader sense. “NASA independently examined advanced LASIK and determined that it was good enough for the astronaut,” Dr. Schallhorn says. “That should give comfort to patients contemplating having the procedure.”
Courtesy of ARAcontent
EDITOR’S NOTE:
For more information, contact John Ciccone at the American Society of Cataract and Refractive Surgery at jciccone@ascrs.org .
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