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Synthetic Eye Prosthesis May Offer Help
Joachim Storsberg developed the
basics for a corneal prosthesis
made of plastic; © Fraunhofer
Donor corneas are a rarity: In Germany alone, each year roughly 7,000 patients wait for that miniscule piece of tissue. An implant made of plastic may soon offer patients with the chance to see again.
Joachim Storsberg of the Fraunhofer Institute for Applied Polymer Research IAP in Potsdam-Golm developed material and production process for a corneal prosthesis made of plastic. These can help patients who are unable to tolerate donor corneas due to the special circumstances of their disease, or whose donor corneas were likewise destroyed.
The miniscale artificial cornea has to meet almost contradictory specifications: On the one hand, the material should grow firmly together with the cells of the surrounding tissue; on the other hand, no cells should settle in the optical region of the artificial cornea - i.e., the middle - since this would again severely impair the ability to see.
And: The outer side of the implant must be able to moisten with tear fluids, otherwise the implant will cloud up on the anterior side. This would consequently require the patient to get a new prosthesis after a relatively brief period of time. And: The outer side of the implant must be able to moisten with tear fluid, so that the eyelid can slide across it without friction.
Storsberg found the solution with a hydrophobic polymer material. This material has been in use for a long time in ophthalmology, such as for intraocular lenses. In order for it to satisfy the various characteristics required, complex development steps were necessary. The material was thoroughly modified on a polymer-chemical basis, and subsequently re-tested for public approval.
In order to achieve the desired characteristics, the edge of the implant was first coated with various, special polymers. Then, a special protein was added that contains the specific sequence of a growth factor. The surrounding natural cells detect this growth factor, are stimulated to propagate and populate the surface of the corneal margin. Thus, the cells of the surrounding tissue grow with the implant, and the artificial cornea attains stability.
By 2009, a prosthesis was already successfully in use; further implantations are anticipated during the first six months of 2010.
REHACARE.de; Source: Fraunhofer-Gesellschaft
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( Source: REHACARE.de )