New Plastic Cornea to Bring Sight to Millions
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20 May 2010
Researchers build an artificial plastic cornea to help patients suffering from corneal blindness the second most common type of blindness in the world...
According to a bulletin by World health organisation approximately 4.9 million individuals have corneal blindness around the world. Considering the abysmal eye donation rates several of them will die before they get a transplant.
For many of these patients who become blind after an accident or illness, a corneal transplantation could restore the ability to see.
Joachim Storsberg of the Fraunhofer Institute in Germany has 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 –the middle –since this would again severely impair the ability to see.
In addition 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. Plus 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 ophthalmological procedures.
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.
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. The research team needed three years to fully develop the artificial cornea and a test prosthesis is currently in use.