Illustrative photo by Nati Shohat/FLASH90
Illustrative photo by Nati Shohat/FLASH90

There’s good news out of Tel Aviv for the people facing corneal transplants.

Prof. Abraham Katzir, head of the Applied Physics Group at Tel Aviv University’s School of Physics and Astronomy, suggests a radically new way to seal the incisions in the eye using a technique he devised called temperature-controlled laser bonding.

“Every year, for 50,000 Americans on the verge of losing their sight, corneal transplants are the only option. It is a torturous procedure followed by many months of painful recovery caused by sutures left in the eye,” said Katzir. “Using our special optical fiber, we were able to seamlessly bond corneal tissue without causing damage to the surrounding eye or leaving lingering stitches.”

He and colleagues from the university and from Tel Aviv Sourasky Medical Center described the procedure in a recent issue of the Journal of Biomedical Optics.

“A surgeon needs great skill to perform internal stitching, to bond tiny blood vessels or to mend cuts on the skin almost without a trace,” said Katzir. “Therefore, there has been great interest in the medical community in levelling the playing field, devising new technology that all surgeons — even those without years upon years of suturing experience — can use.”

An innovative fiber

Katzir’s group developed optical fibers made of silver halides. The fibers deliver an infrared laser beam that heats spots on the edges of an incision in a carefully controlled manner, and also deliver infrared light from the heated spot to an infrared detector, which monitors the temperature. This makes it possible to heat each spot to just the right temperature –140 to 150 degrees F — to create a strong bond without causing thermal damage.

“The most important aspect of our technique is temperature,” said Katzir. “Take an egg, for example. If you cook it at 70-80 degrees F, nothing happens. However, if you fry it at 250 degrees F, you destroy it altogether. At an intermediate temperature, however, one gets a hard-boiled egg. The same goes for laser bonding, where heating at an intermediate temperature, under precise controls, ensures strong bonding without scarring.”

In collaboration with surgeons from Tel Aviv and Sheba medical centers, Katzir and his team did corneal transplants in eyes taken from deceased cows and pigs. They used the fiber-optic laser system to achieve a permanent tight seal with minimal thermal damage to the surrounding eye tissue. Conducting biopsies on the eyes, the researchers found neither leaks nor signs of overheating.

For robotic surgeries, too

Based on these results, Katzir has received approval to conduct corneal transplant experiments on live animal models. In parallel, he is applying his technique to endoscopic surgeries.

“This least invasive surgery is the way the medical world is moving,” said Katzir. “One of the most difficult tasks facing surgeons is the closure of incisions in such surgeries. Our technique is based on thin and flexible optical fibers that can be inserted through the endoscope to facilitate laser bonding within the body. This new technique is poised to be a major player in such surgeries and in the fast-growing field of robotic surgery in particular.”

In recent clinical trials involving 10 human patients, skin wounds treated with the fiber-optic laser technique successfully healed, with almost no scar tissue.

“There are endless applications for the fiber-optic laser system,” said Katzir. “Plastic surgery, urology, ENT, brain surgery, emergency medicine, battlefield wounds — the possibilities are truly endless. I hope that we will be able to apply our innovative technology to some of these fields.”

In the future, the technique could be made available via some sort of tissue-bonding apparatus integrated with an optical probe.