With a new method, doctors can stabilize a pathologically altered cornea and restore vision in some patients. They also developed an operation method that does not require sutures. As a result, the patients had good wound healing and there were no complications.
The method was successfully tested on 20 patients in Iran and India, as reported by the team led by Mehrdad Rafat and Neil Lagali from the Swedish University of Linköping in the journal "Nature Biotechnology".
An estimated 12.7 million people worldwide are blind due to a corneal injury or disease. A large proportion of these people suffer from the eye disease keratoconus, in which the cornea becomes progressively thinner and tapers into a cone. This astigmatism can severely impair vision, even leading to blindness.
The team led by Rafat and Lagali developed an artificial cornea made of collagen, which is obtained from the skin of pigs and - highly purified - can be used medicinally. Since pork skin is a waste product of the meat processing industry, the starting material is available in large quantities.
Natural collagen, the main component of gelatin, is very soft and malleable. To make it stiffer, the researchers chemically and photochemically created a crosslink in the collagen. They also tested the material for biocompatibility and durability.
In a first attempt with pigs, the artificial cornea was inserted into the existing cornea and the surgical incision was sewn up. Because the cornea then thinned again and a haze formed, Lagali and colleagues developed a surgical method without sutures and changed the manufacturing process of the implant.
Clinical trials with 20 patients in Iran and India, where there are many keratoconus sufferers, were successful. 14 of them had previously been blind, after the operation all of them could see again. The patients only had to take eye drops for eight weeks to prevent an inflammatory reaction.
With the method used up to now, corneal transplantation, considerable follow-up treatments are often necessary. A donor cornea is also required. This can usually be kept for up to four weeks, by which time it must have been transplanted. In many parts of the world, this storage causes difficulties.
That's why Rafat, Lagali and colleagues tested how long their artificial cornea can be stored: at least two years. "We have made significant efforts to ensure that our invention is available and affordable for everyone, not just the rich," Rafat said.
The visual acuity achieved by the patients in the clinical trials varied, but in three patients it reached that of a healthy eye. The experiments were not designed for optimal visual acuity. With individual attention to corneal thickness, curvature and refractive errors, the results could be significantly improved, the researchers are optimistic. They announce further clinical studies.
Gerd Geerling, President of the German Ophthalmological Society (DOG), speaks of a high-quality and very carefully conducted study. "The researchers are presenting a well thought-out concept that also takes into account the general conditions in many countries," says the expert from the Düsseldorf University Hospital. If the implants were not offered too expensively, many keratoconus patients around the world could be treated with them, especially in countries that do not have such a good health system as Germany.
According to Geerling, there is currently no such pronounced shortage of donors in Germany. A medical product made from cell-free pig cornea is already on the market, but it is about as expensive as a human donor cornea. Under certain circumstances, however, the new method could also be used in Germany after approval, explains Geerling.
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