Laser "Scalpel" Improves Popular Eye Surgery; Ultrafast Pulse Offers High Precision For Cutting Corneal Flap

The laser technology and surgical procedures were developed at the University of Michigan by a joint team of physicists and ophthalmologists from the National Science Foundation (NSF) Center for Ultrafast Optical Science (CUOS) and the university's Kellogg Eye Center. The team reports on the procedure in the June 2001 issue of Ophthalmology Clinics of North America.

"The collaborations were very important in this project, which allowed us to apply the precision of physics and materials science to a medical application that benefits a large number of people," said CUOS Director Gérard Mourou.

LASIK surgery, or laser in situ keratomileusis, has revolutionized vision correction surgery. In traditional LASIK surgery, a mechanical blade called a microkeratome is used to cut a flap of cornea, an excimer laser is used to reshape or remove a portion of the cornea, then the flap is repositioned. Now, surgeons can use the very precise femtosecond laser to create the initial flap. The laser emits light in extremely fast pulses, each pulse roughly a billion times faster than an electronic camera flash.

Use of the femtosecond laser to cut corneal flaps is more precise than previous methods, reduces the chance of uneven cuts or collateral tissue damage, and improves clinical safety.

"The path from an NSF Science and Technology Center to the marketplace is an excellent example of how federal funding of basic research can lead to new technologies with broad social benefit," said Robert Eisenstein, NSF's assistant director for mathematical and physical sciences. "The cross-disciplinary effort of the team was an important factor in this research."

Lasers with ultrashort pulse durations--a femtosecond is one millionth of a billionth of a second--have been researched extensively for the machining of materials on the micrometer-scale, but they are new to medicine. In attempting to harness their tremendous intensity, the scientific team discovered they were able to cut tissue with unsurpassed precision. The laser's intensity is thousands of times greater than are those of conventional lasers used in medicine.

Two members of the Michigan team, Tibor Juhasz and Ron Kurtz, founded the IntraLaseTM Corporation to commercialize the new laser, with support from NSF, the National Eye Institute of the National Institutes of Health, and the Department of Defense in the form of Small Business Innovative Research (SBIR) grants. The IntraLaseTM product, the Pulsion FSTM laser, was introduced at the American Society of Cataract and Refractive Surgery meeting in San Diego, Calif., in April 2001. It is expected to be widely available in the United States within a year.

Researchers are now exploring the possibility of extending this technique to other eye procedures, such as cornea transplants or glaucoma treatment. One potential application is creating new drainage systems in the eye when those systems are not functioning adequately.

"We have barely begun to explore the myriad of uses that the femtosecond laser offers in the clinical management of glaucoma," said Paul Lichter, director of the Kellogg Eye Center.