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Wednesday, October 10, 2007 Eye RepairFor millions with eye damage, a new artificial cornea could prove a safer, more effective treatment.
A novel artificial cornea that adheres to eye cells could bring new hope to the estimated 10 million people worldwide who are blind because of corneal damage or disease. The new design should relieve some of the complications--such as tissue rejection--that often accompany corneal transplants or the implantation of existing artificial corneas. The device, which has been extensively tested in rabbits, is expected to be in clinical trials early next year. Existing artificial corneas are held in place solely by sutures, which leaves patients susceptible to inflammation, infection, and even losing an eye, says John Huang, an assistant professor in the Department of Ophthalmology and Visual Science at the Yale University School of Medicine. "We certainly need a better way to get an artificial cornea in place," he says. Today's implants are large--"just one big piece of plastic," says Huang--but they have to be, to prevent excess corneal tissue from growing over them and impairing patients' vision. In the long run, however, their size can be problematic: the difficulty of stitching them into place increases the chance that the surgical wound will reopen or become inflamed, says Huang. The implants are also too big to be stitched directly to eye tissue. Instead, they are built around a layer of corneal tissue extracted from a donor, which acts as a bridge to the recipient's tissue. The key to the new implant is a protein-coated polymer developed by researchers at the Fraunhofer Institute, in Postdam, Germany; the group is led by Joachim Storsberg, head of the institute's medical-polymer research unit. The polymer, which is commercially available, repels water, so it won't absorb tear-duct secretions that could cause it to swell. It also prohibits cell growth, so natural tissue will not cloud it over. This is an advantage at the center of the implant, which needs to remain clear. But it would be a disadvantage at the edges, which need to bind to existing corneal tissue. So the outer rim of the cornea is coated with a protein that attracts existing corneal cells. "This special coating allows the implant to firmly connect with the cells [of the natural cornea]," says Storsberg. Although the new implant still has to be sutured into place, that firm connection helps prevent the kind of infection that posed problems in earlier implants. The protein was also chosen for its ability to withstand the thermal sterilization process that the device must go through to meet medical-safety requirements. And because the German researchers' polymer prevents cell growth, the implant can be made small enough to be sutured directly to the eye. As a consequence, the layer of donor tissue is unnecessary. This is a "huge advantage," says Huang. Donor corneal tissue is in short supply, so existing implants end up using tissue of poor quality. |
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Artificial Cornea Mimics Natural Counterpart
05/22/2008
Comments
kris.38 on 10/10/2007 at 6:01 AM
2
deirdrebeth on 10/10/2007 at 2:35 PM
25
lmburk on 10/17/2007 at 6:09 AM
1
I had RK/AK surgery and had over 30 cuts per eye. My vision is poor with quadruple vision, blurriness, star bursts, and radial rings around bright lights that blind me at night while driving. The shape of my corneas is like a pie that fell after removing from the oven. It is now concave in shape not convex.
Contact lenses are helping, but in my line of work as an electronic engineer, I feel my vision is becoming more a hindrance. Can I see, Yes. But for my career, not so good. I no longer have fine detail in my vision. Can't read well the fine print on electronic components without the aid of a microscope (reading glasses are useless) when a person of normal vision has no troubles.
I suffer multiple vison of shapes causing such fuzziness that I can no longer see clearly. If I have to continue to defer my work to a person with better vision, I feel my employer may decide to remove me for a better sighted person because I take longer and am costlier to do the work.
It feels funny and yet, doesn't work well to wear contact lenses and glasses at the same time in order to see.
The cornea is the problem - contact lenses and glasses are the band-aids. I really hope this new artificial cornea works because I'm learning that there are others, like me, with the same or similar problem I am experiencing. All we want is our clear and sharp vision back. It seems to me replacing a broken or run-down cornea even if there is still vision capability is a better solution than the band-aids. Especially when a career is on the line. Its what is driving people to risk the AK/RK and Lasik surgeries in the first place. To get rid of the contacts and glasses that are an inconvenience and a nuisance.
Lonnie Burk
visioncareindia on 10/21/2007 at 7:31 AM
1
anita.handa on 04/21/2008 at 8:12 AM
1