Clearer vision, without the cutting

For most of his career, mechanical and aerospace engineering professor Szymon Suckewer has built high-powered devices that stretch the limits of laser technology. When he began collaborating with an eye surgeon and several faculty colleagues to explore applications in laser eye surgery seven years ago, the relatively low-power lasers used in the field seemed almost trivial by comparison. But what began as a hobby has produced exciting results, including an “elegant, simple” technique for reshaping the cornea that Suckewer says could dramatically improve corrective eye surgery.

Laser eye surgery generally involves cutting and peeling back a small flap in the surface of the cornea and reshaping the cornea’s middle layers by removing thin layers of tissue with brief laser pulses lasting just 10- to 20-billionths of a second. Suckewer’s alternative bypasses the first step — cutting the flap — and reshapes the cornea below the surface using a femtosecond laser, which uses pulses 100,000 times shorter than those used in ordinary LASIK surgery. The process emits less heat, and because there is no cutting on the surface of the cornea, it could reduce a patient’s recovery time, according to Suckewer. “It’s like going from a very dull knife to a very fine scalpel,” he says.

Cornea reshaping is one of several ophthalmic applications of the femtosecond laser that Suckewer has explored with collaborators Dr. Peter Hersh ’78 and Peter Frederikse of the University of Medicine and Dentistry of New Jersey, and Princeton engineering professors Richard Register and Alexander Smits. The group also has obtained a provisional patent for its method to correct lenses in the eyes of patients who suffer from presbyopia, a deterioration of near vision that is linked to aging. The technique involves removing crystalline tissue from the eye lens with the femtosecond laser and replacing that tissue by injecting a polymer into the lens through a channel created by the laser.

Suckewer and his team are working to translate the concepts demonstrated in the lab into medical applications. While laser eye surgery is relatively safe, he says, there is a market for incremental improvements. One popular example is “blade-free” cornea reshaping, which uses a femtosecond laser to cut the corneal flap and a nanosecond laser to reshape the cornea.

Even on an optimistic timeline, Suckewer says that clinical applications of the work he and his colleagues have done are about three years away. The techniques, which Suckewer and his team have tested in animal eyes, need to be calibrated with computer algorithms that direct lasers to precisely reshape tissue. After that would come clinical trials on animals and, eventually, humans. Suckewer, who wears glasses to correct his far-sighted vision, plans undergo the technique when the animal trials are complete. “It is the principle,” he says. “If you believe your system is working, you should try it on yourself first.”