The artificial retina is the first device of its kind to move from the laboratory to the clinic, after a trial of 30 patients, ten of whom were treated in Britain, has shown that it can safely restore some vision to people who have lost their sight to a genetic disease.
Argus II uses a camera on dark glasses to send signals to a network of 60 electrodes implanted in the retina, which relays them to the optic nerve. Patients with no sight who have received the prosthetic retina can see light, motion and colour, discern the outlines of objects, and even read large letters on a computer screen.
The implants are designed for patients with retinitis pigmentosa (RP), a degenerative and incurable disease that affects about one in 4,000 people. It damages the light-sensitive rod and cone cells of the retina, leading to impaired vision in poor light, followed by tunnel vision that often deteriorates into complete blindness.
The results of the trial, presented at the weekend at the Euretina ophthalmology conference in London, represent a landmark in bionic eye technology because they demonstrate that electronic implants can reliably restore worthwhile sight.
Lyndon Da Cruz, a consultant ophthalmic surgeon at Moorfields Eye Hospital in London who treated seven of the ten British patients, said: "Patients with RP who can afford it can now have an artificial retina. It is proof of principle, always the great unknown with new technology.
"This demonstrates that plugging in technology to the neural structure of the eye is possible, and that this can integrate stably over a long period. Now we have something that works we can begin to think about how to make it better."
The award of a CE mark to the device means that it can be given to private patients, at a cost of $A81,000. Recipients also require training in the use of device, which costs a further $A17,000.
Argus II is not yet available on the NHS, though Second Sight, the company that makes it, has applied to the National Specialist Commissioning Advisory Group for approval and the matter has been referred to the National Institute for Health and Clinical Excellence.
Gregoire Cosendai, vice president of Second Sight, said: "The initial feedback has not been favourable, but reimbursement has been agreed in other countries and we are making the case. As the cost of supporting a blind person over a lifespan is 3 million pounds to 4 million pounds ($3.6-$6.1 million), we believe this can save money.
"The approval is very significant because no treatment like this has been approved in patients before. There is no therapy for retinitis pigmentosa, which makes it a difficult diagnosis for doctors and patients. They know that they are going to lose their sight."
Mr Da Cruz said he had not yet treated any private patients with the device. Dr Cosendai said that his company was manufacturing devices, and expected to begin selling them this summer.
To use Argus II, patients first have an operation to fit an implant, which includes a radio receiver and an electrode pad that stimulates the ganglion cells of the retina. After recovering from the surgery, they can begin to use the camera mounted on dark glasses.
Images are converted into electrical pulses, using a computer about the size of a wallet that can be worn around the neck. These pulses are transmitted wirelessly to the implant, and the electrodes turn them into pixels of light.
Improved versions may be suitable for people with other conditions.
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