July 10, 2008 Faster recovery times and better visual outcomes are among the early results of a corneal transplant pilot study underway at the University of Michigan Kellogg Eye Center.
The focus of this two-year pilot program – called the Femtosecond Laser Assisted Keratoplasty study, or FLAK – is the use of the ultrafast or femtosecond laser in performing full thickness corneal transplants.
Researchers at Kellogg were first to discover in the early 1990s that the femtosecond laser, then used for industrial purposes, had great potential for eye surgeries that traditionally required a surgical blade or knife. Through joint efforts of faculty from Kellogg and the U-M College of Engineering, the femtosecond laser was further developed, and is widely used for refractive surgery. Now, experts hope for the same success in applying this exceptionally fast and precise laser to cornea transplant surgery.
“We hope that with the use of the femtosecond laser, patients will have better vision, faster recovery of vision, and stronger wound construction, which will allow them to be more resistant to injury in the future,” says Shahzad I. Mian, M.D., assistant professor in the Department of Ophthalmology and Visual Sciences at Kellogg, and principle investigator of the FLAK study.
While lasers have been effective in eye surgeries for decades, they were not used for corneal transplants until the femtosecond laser was shown to be a superior cutting tool to the trephine, the cookie cutter-like knife currently used for transplants.
“The advantage of this laser is that it allows the surgeon to focus the laser energy at a particular depth and then rapidly cut the tissue at that depth without causing any additional injury to the surrounding tissue,” says Mian. “It also allows the surgeon to pattern these cuts into shapes – such as a mushroom, a top hat or a zig zag – that allow for better customized overlap between the donor’s corneal tissue and the patient’s corneal tissue.”
Because of the speed and precision of the femtosecond laser, the study results to date for corneal transplant surgery have been very encouraging, says Mian. If these results hold true, a larger, multi-center clinical trial comparing this procedure to the traditional method of performing transplants could follow.
About corneal transplants
The cornea is the clear, dome-shaped tissue covering the front of the eye. It is about the size of a dime and the thickness of a credit card. If the cornea becomes distorted in shape, or scarred or hazy from disease or injury, the light rays passing through it are distorted and vision is reduced. In some cases, corneal transplant surgery may be necessary to replace the damaged cornea with a healthy donor cornea to restore good vision.
Donor corneas are provided by eye banks and come from deceased individuals who arranged for donation prior to death or whose families gave consent.
Ophthalmologists perform more than 35,000 of these sight-saving procedures each year in the United States and, of all transplant surgeries done today, corneal transplants are the most common and most successful.
According to results from the National Eye Institute of the National Institutes of Health’s Cornea Donor Study, the pool of cornea transplant donors – often limited to those age 65 and younger – should be expanded to include donors up to age 75.
The study, conducted during a five-year period at 80 eye centers, including Kellogg, proved that the transplant success rate was the same – 86 percent – for transplants performed with corneas from donors ages 12 to 65, and from donors ages 66 to 75.
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