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New Artificial Cornea Shows Promise

May 16, 2008 — Researchers from Stanford University have developed an artificial cornea, which they say could make cornea transplants involving donors a thing of the past and help millions of blind people see again.

The polymer-based cornea has not been implanted in humans, but it is showing promise in animal studies, Stanford senior scientist Jaan Noolandi, PhD, tells WebMD.

Corneal disease is a leading cause of blindness. Examples of corneal disease include infection such as ocular herpes and corneal dystrophy such as keratoconus. It is estimated that 10 million people worldwide have lost their sight to corneal disease or illness.

Transplants from cadaver donors are not an option in many parts of the world, due to shortages of donors or religious barriers to human tissue transplant.

“There is really a global market for an artificial cornea, and we believe that our material will prove more biocompatible than those that have been tried in the past,” Noolandi says.

Doing Away With Donors

Developed by chemical engineer Curtis W. Frank, PhD, the cornea is made of two interwoven polymer gels, similar to the materials used in soft contact lenses.

One layer is exceptionally strong while the other is able to absorb a tremendous amount of water.

The result is a transparent, highly permeable substance with a water content similar to that of the natural cornea, Noolandi says.

“Without a high water content the nutrients that feed the cells within the eye can’t penetrate and the cells eventually die,” he adds.

If the artificial cornea proves successful in human studies, it could one day replace donor transplants.

But that is a very big if, says corneal disease specialist Ivan Schwab, MD.

“There have been dozens of attempts to come up with some version of an artificial cornea over many decades,” he tells WebMD. “Most have looked promising in the lab but have proven disappointing otherwise.”

He says that is the case with one of the only artificial corneas now approved for use in the U.S., which was developed by researchers in Australia.

The failure rate among patients who get the AlphaCor cornea is about 20% a year.

“Until the [Stanford] researchers publish human, or even animal studies, we won’t really know if their approach is promising,” he says. “They may have something terrific, but I am skeptical because of the many previous failures.”

Human Studies Needed

Harvard Medical School professor of ophthalmology Claes H. Dohlman, MD, PhD, has been conducting cornea research for more than 50 years, and he is considered a founder of modern corneal science.

The artificial cornea he developed has been used in the U.S. since 1992 in patients who are not candidates for donor transplants.

His artificial cornea cannot be used when corneal damage is caused by autoimmune disease, but Dohlman says it works very well in other patients.

“The search [for a safe and effective artificial cornea] goes as far back as the surgeons of the French Revolution, with mostly disastrous results,” he tells WebMD. “It has only been within the last few decades that the elements have come together to make this a reality.”

Dohlman agrees that it remains to be seen if the artificial cornea developed by the Stanford researchers will advance the search for a donor transplant replacement.

“This is a very good research team, but they still have a long way to go,” he says.

Posted by: Dr.Health

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