Posts tagged eye
For the thousands of people who go blind every year from damage to the cornea (though trauma, disease, or missing limbal stem cells), a new cure may be in sight. The established treatment — a corneal transplant — requires finding suitable donors and doesn’t work for some patients. Now, German researchers are working to develop an artificial, implantable cornea.
The ART CORNEA project team, led by scientists at the Fraunhofer Institute for Applied Polymer Research, has developed two types of artificial corneas.
ArtCornea is for patients whose bodies reject transplanted corneas. The cornea is based on a water-absorbent polymer with a new surface coating and chemically altered haptic edge that promotes the growth of local cells that graft to the surrounding tissue, anchoring the implant into the patient’s eye. The researchers enlarged the device’s optical surface area, improving light penetration. The team says ArtCornea is hardly visible and does not trigger an immune response.
ACTO-TexKpro is for patients who are awaiting a transplant. The team developed a chemically and biologically inert base material by coating polyvinylidene diflouride synthetic tissue with a reactive molecule. This allows the patient’s cornea to bond with the edge of the implant, yet keeps the implant’s silicon optics free of cells. The team says ACTO-TexKpro is suitable as a preliminary treatment for people whose corneas have been destroyed by chronic inflammation or a serious accident or burns.
The team has successfully tested the artificial corneas in rabbits, and human clinical trials are commencing at the Eye Clinic Cologne-Merheim. The team is optimistic — several patients whose bodies had rejected human transplants received an early version of the artificial cornea in 2009 and are still wearing their implants today without complications.
A new type of artificial retina may one day allow blind people to see with much greater detail than today’s prosthetic eyes allow. The new system, described in a study by Sheila Nirenberg and Chethan Pandarinath of the Weill Cornell Medical College in New York, was designed to work more like frontline photoreceptor cells naturally do. ”If you want to really restore normal vision, you have to know the retina’s code,” Nirenberg said. “Once you have that, the door is open to the possibility of restoring normal vision.”
In mouse testing, the researchers found the new retina (center photo above) sensed more details of the original image (left) than current systems (right). ”Incorporating the [more accurate] code jumped the system’s performance up to normal levels – that is, there was enough information to reconstruct faces, newsprint, landscapes, essentially anything,” said Nirenberg. Prosthetic eyes may one day benefit over 25 million people worldwide who have lost sight due to retinal diseases– the next step forward is to begin studies in humans.
The FDA just approved a tiny implantable telescope meant to assist patients over 75 years old who suffer from end-stage macular degeneration. In a clinical trial with over 200 patients, seventy-five percent of patients with the implant “had their vision improve from severe or profound impairment to moderate impairment.” The manufacturer, VisionCare Opthalmic Technologies, is planning a follow-up study with these patients, along with another one involving 770 new patients.
The device replaces the eye’s natural lens and provides a magnified image (the two available versions offer 2.2x or 2.7x zoom), which is then projected onto a healthy part of the patient’s retina. The implant can only be used in one eye, as the other eye is needed for peripheral vision. Since the brain has to adjust to the implant’s image, patients must go through rehabilitation for the telescope to work. The FDA warns the treatment is still risky and could even necessitate a corneal transplant.
VisionCare says each implant will cost $15,000, so start saving up.
Bionic Vision Australia, in collaboration with a team at the University of New South Wales, has unveiled a working prototype of a bionic eye implant. The system uses an eyeglass-mounted camera and pocket image processor that wirelessly transmit the image to a receiver implanted in the eye. The implant is a chip with 98 electrodes that directly stimulate neurons in the eye’s retina, which can restore some vision to people with optical nerve problems like retinitis pigmentosa and age-related macular degeneration.
The company plans to start clinical trials later this year, with normal patients receiving the implants by 2013.
Full press release after the break.