Laser ‘scalpel’ offers high precision

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ANN ARBOR—A cross-disciplinary team of researchers at the University of Michigan has developed a procedure for using an ultrafast laser to make clean, high-precision surgical cuts in the human cornea. The procedure, which is expected to reduce complications associated with the popular LASIK eye surgery, was tested in clinical trials and received Food and Drug Administration approval earlier this year.

A report on the procedure appears in the June issue of Ophthalmology Clinics of North America.

The Michigan team was comprised of engineers and medical professionals associated with the University’s Center for Ultrafast Optical Science (CUOS)—a National Science Foundation (NSF) Science and Technology Center—and the Kellogg Eye Center, respectively.

“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.

Two Michigan researchers—Tibor Juhasz, an associate professor of biomedical engineering, and Ron Kurtz, an assistant professor of ophthalmology and visual sciences—co-founded IntraLase^TM Corporation to commercialize the new laser, with additional support from NSF, the National Institutes of Health National Eye Institute, and the Department of Defense. The IntraLase^TM product, the Pulsion FS^TM, was introduced at the American Society of Cataract and Refractive Surgery meeting in San Diego in April.

LASIK, 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, reducing 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 have been researched extensively for the machining of materials on the micrometer-scale, but are new to medicine. In attempting to harness their tremendous intensity, which is measured in femtoseconds (one millionth of a billionth of a second), 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.

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.

[email protected]LASIKCenter for Ultrafast Optical ScienceGérard MourouTibor JuhaszCorporationRobert Eisenstein