Artificial Cornea Implants on the Horizon

Scientists at the Fraunhofer Institute for Applied Polymer Research IAP in Potsdam, Germany, and the Department of Ophthalmology at the University Hospital of Regensburg, Germany, have developed a workable artificial cornea. Clinical human tests are supposed to start in early 2008.

People, who have a damaged cornea due to a congenital malformation, a hereditary disease, or accidental corrosion, are oftentimes at risk of losing their eyesight. These patients only hope of keeping from going blind is a cornea transplant. Unfortunately, as it is the case with other donor organs, donor corneas are rare.

A cornea transplant involves removing the patient's cornea in a circular fashion. An outer ring of the natural cornea usually remains for the donor cornea to be attached to. Then the donor cornea is put into place through sutures. Since donor corneas are rare, many scientists have made attempts at developing artificial corneas with very little success.

The problem is the way the artificial cornea has to work with the patient's eye environment. The artificial cornea has to be attached tightly to the natural tissue at the edges of the circular incision. It ideally grows into it just like a donor cornea would. However, the material the artificial cornea is made off, cannot allow cells to grow in the center of the cornea. This would reduce the patient's vision. This material problem is the cause of many failed attempts at the creation of an artificial cornea.

The scientists in Potsdam and Regensburg, Germany, use a commercially available polymer for their artificial cornea. This polymer does not absorb water. Furthermore, cells cannot grow on the polymer. The polymer is shaped to resemble a cornea. Then the artificial cornea implant is coated with masks. A special protein is applied around the edges of the cornea.

This protein allows the cells of the remaining natural cornea to latch onto the artificial implant. This provides a firm connection with the natural cornea. Yet the center of the implant remains clear and free of cells.

This protein can even survive the thermal sterilization process the artificial cornea undergoes before implantation. The scientists also add a hydrophilic polymer coat to the optical front portion of the artificial cornea. This allows the implant to be continuously moistened by the patient's tear fluid.

The artificial cornea has performed well in laboratory tests. Furthermore, tests of the implants on rabbits' eyes have begun with promising results. The scientists expect to start human trials in early 2008.