Friday, October 19, 2012

Artificial cornea gives the gift of vision

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Blindness is often caused by corneal diseases. The established treatment is a corneal transplant, but in many cases this is not possible and donor corneas are often hard to come by. In the future, an artificial cornea could make up for this deficiency and save the vision of those affected.

Our eyes are our window to the world. Thousands of people have lost their eyesight due to damages to the cornea, such as trauma, absent limbal stem cells or diseases. Transplantation of a donor cornea is the therapy of choice for a great number of those patients. Let alone the issue of scarce donor material, a sub-group of patients do not tolerate transplanted corneas, necessitating the employment of an alternative means of restoring eye sight. In Germany alone, around 7,000 patients are waiting to be treated. In close cooperation with the Aachen Centre of Technology Transfer, Dr. Storsberg and his team from the Fraunhofer Institute for Applied Polymer research IAP in Potsdam, are attempting to improve the situation by developing an artificial cornea. Scientific partners in the "ART CORNEA" project include the Martin Luther University of Halle-Wittenberg, ACTO e. V. and the Ophthalmic Clinic Cologne-Merheim.

"We are in the process of developing two different types of artificial corneas. One of them can be used as an alternative to a donor cornea in cases where the patient would not tolerate a donor cornea, let alone the issue of donor material shortage," says IAP project manager Dr. Joachim Storsberg. The scientist has considerable expertise in developing and testing of next-generation biomaterials. Between 2005 and 2009 he collaborated with interdisciplinary teams and private companies to successfully develop an artificial cornea specifically for patients whose cornea had become clouded - a condition that is extremely difficult to treat. Such patients are unable to accept a donor cornea either due to their illness or because they have already been through several unsuccessful transplantation attempts. Dr. Storsberg was awarded the Josef-von-Fraunhofer Prize 2010 for this achievement. "A great many patients suffering from a range of conditions will be able to benefit from our new implant, which we've named ArtCornea®. We have already registered ArtCornea® as a trademark," reports Storsberg.

Ultima ratio patients regain vision

ArtCornea® is based on a polymer with high water-absorbent properties. Dr. Storsberg and his team have added a new surface coating to ensure anchorage in host tissue and functionality of the optic. The haptic edge was chemically altered to encourage local cell growth. These cells graft to the surrounding human tissue, which is essential for anchorage of the device in the host tissue. The researchers aimed to enlarge the optical surface area of the implant in order to improve light penetration beyond what had previously been possible - a tall order. "Once ArtCornea® is in place, it is hardly visible, except perhaps for a few stitches. It's also easy to implant and doesn't provoke any immune response," says Storsberg, highlighting the merits of this new development.

The specialists have also managed to make a chemically and biologically inert base material biologically compatible for the second artificial cornea, ACTO-TexKpro. Dr. Storsberg achieved this by selectively altering the base material, polyvinylidene difluoride, by coating the fluoride synthetic tissue with a reactive molecule. This allows the patient's cornea to bond together naturally with the edge of the implant, while the implant's inner optics, made of silicon, remain free of cells and clear. The ACTO-TexKpro is par-
ticularly suitable as a preliminary treatment, for instance if the cornea has been destroyed as a consequence of chronic inflammation, a serious accident, corrosion or burns.

The experiments were carried out in collaboration with Dr. Norbert Nass and Dr. Saadettin Sel, Senior consultant ophthalmologist at Martin-Luther-University Halle-Wittenberg. How well TexKpro and ArtCornea® are accepted by clinicians as an additional tool at their disposal was first tested by the doctors in the laboratory thereafter in vivo in several rabbits. After a six month healing process, the implanted prostheses were accepted by the rabbits without irritation, clearly and securely anchored within the eye. Tests carried out following the operation showed that the animals tolerated the artificial cornea well. Prof. Dr. Norbert Schrage will take charge of clinical trials that will soon commence at the Eye Clinic Cologne-Merheim. It is likely that the positive results of tests carried out thus far will be confirmed, and the co-operation partners rate the chances of success very highly. Their optimism is well founded: As early as 2009, several Ultima-Ratio patients received implants of a Kerato prosthesis specially developed for them because they had previously rejected human corneas. These patients have not suffered any complications and are still wearing their artificial corneas today.


Synthetic eye prosthesis
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 - especially those facing their last resort - with the chance to see again.

Corneal transplant technique shows promise in children
For infants and children with blinding diseases of the cornea, a sophisticated new corneal transplantation technique offers the hope of improving vision while overcoming the technical difficulty and low success rate of traditional penetrating keratoplasty (PK) in children, according to reports in the current issue of the Journal of AAPOS (American Association for Pediatric Ophthalmology and Strabismus).

Artificial cornea offers better results for infants, some blind patients
Infants and adults who are blind due to a cloudy or damaged cornea are seeing some remarkable results thanks to a new version of an artificial implant that takes the place of the cornea, the clear covering of the eye that serves as our window on the world.

An artificial cornea is in sight, thanks to biomimetic hydrogels
If eyes are "the windows of the soul," corneas are the panes in those windows. They shield the eye from dust and germs. They also act as the eye's outermost lens, contributing up to 75 percent of the eye's focusing power.

Artificial sight
An engineering team at the University of Dundee has just secured funding to work with European colleagues on the construction of artificial corneas which will allow all cornea replacements to go ahead without the patient having to wait for a donor. The Euro 2.4m project will help people who suffer from a number of diseases requiring corneal grafting including keratoconus - a thinning of the cornea. Instead of relying on donor corneas from an eye bank, the new technology invented by biochemists, tissue engineers and structural engineers will allow the European team to grow the cornea from human stem cells in a test tube. The team of structural engineers at the University of Dundee who will be More Artificial Cornea Current Events and Artificial Cornea News Articles
Artificial Cornea in Sight.(source of tissue for corneal transplants is cadavers)(white blood cells that fight infection): An article from: Transplant News
by Gale Reference Team (Author)

This digital document is an article from Transplant News, published by Thomson Gale on November 1, 2006. The length of the article is 508 words. The page length shown above is based on a typical 300-word page. The article is delivered in HTML format and is available in your Digital Locker immediately after purchase. You can view it with any web browser.

Citation Details
Title: Artificial Cornea in Sight.(source of tissue for corneal transplants is cadavers)(white blood cells that fight infection)
Author: Gale Reference Team
Publication: Transplant News (Newsletter)
Date: November 1, 2006
Publisher: Thomson Gale
Volume: 16 Issue: 19

Distributed by Thomson...

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