According to a recent study of 208 procedures in 108 patients, femtosecond lasers can make clean, high-precision cuts in the human cornea that offer superior reliability and fewer complications than cuts made with mechanical devices now used in most LASIK procedures. Results of the study were published in the January/February issue of the Journal of Refractive Surgery.

The laser technology and surgical procedure were developed by a joint team of physicists and ophthalmologists from the University of Michigan’s Center for Ultrafast Optical Science (CUOS), its biomedical engineering department and the Kellogg Eye Center. Intralase Corporation, a university spin-off, commercialized the technology and currently has over 40 lasers operating in clinics around the country. Over 30,000 procedures have been safely completed with the new technology.

LASIK, or laser in situ keratomilieusis, surgery reduces refractive error in the eye by reshaping or removing a portion of the cornea with an excimer laser. But before an excimer laser can be used, a thin flap in the cornea must be cut and folded away from the eye to provide better access to the tissue to be sculpted. Creation of this flap is one of the most important steps toward insuring a successful and trouble-free procedure.

In the traditional LASIK procedure, a microkeratome is used to create the flap. Modeled after a carpenter’s plane and invented in the 1950s, the microkeratome relies on a mounted metal razor blade to cut the flap in the cornea. Even in very skilled hands, accurate depth and consistent flap thickness can be difficult to control with the device. Flap-related complications occur in as many as 5 percent of microkeratome LASIK cases, often delaying recovery of visual acuity or occasionally leading to permanent visual loss.

The new University of Michigan procedure replaces the microkeratome with a femtosecond laser, making the procedure completely bladeless and reducing the overall complexity of the surgery. Femtosecond lasers, which emit pulses of light that are a billion times shorter than an electronic camera flash, create a string of 3-micron bubbles just below the surface of the cornea. These bubbles then create a precise and well-defined flap through a process known as photodisruption. The process leaves a more well-defined flap, while doing less damage to surrounding tissue than a microkeratome.

The Michigan procedure represents the first medical application of ultrafast and femtosecond laser technology. However, researchers also hope to use the lasers to create micro-sized drainage ducts in the eye to treat glaucoma patients. In recent years, ultrafast laser science has become one of the most promising areas of study, leading to advancements in manufacturing, high-speed electronics, quantum computing, physics and other areas of research.

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The University of Michigan College of Engineering is consistently ranked among the top engineering schools in the world. The College is composed of 11 academic departments: aerospace engineering; atmospheric, oceanic and space sciences; biomedical engineering; chemical engineering; civil and environmental engineering; electrical engineering and computer science; industrial and operations engineering; materials science and engineering; mechanical engineering; naval architecture and marine engineering; and nuclear engineering and radiological sciences. Each year the College enrolls over 7,000 undergraduate and graduate students and grants about 1,200 undergraduate degrees and 800 masters and doctoral degrees. For more information, please visit our web site at http://www.engin.umich.edu.

Useful Links

http://www.eecs.umich.edu/USL/

http://www.intralase.com/

http://www.journalofrefractivesurgery.com/showAbst.asp?thing=5081

Note: If no author is given, the source is cited instead.

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