Prosthetic retina shows promise in restoring sight

Scientist are developing a prosthetic retina which can restore sight to patients suffering from age-related macular degeneration (AMD), one of the commonest causes of blindness. The thin silicon device acts by electrically stimulating neurons (nerve cells) in the retina, which are left relatively unscathed by the effects of AMD while other image capturing cells, known as photoreceptors, are lost. It requires no wires and would make surgical implantation simpler. Keith Mathieson, study co-author and reader at the Institute of Photonics, University of Strathclyde, UK, said: "AMD is a huge medical challenge and, with an aging population, is continuing to grow. This means that innovative, practical solutions are essential if sight is to be restored to people around the world with the condition," the journal Nature Photonics reports. "The current implants are very bulky, and the surgery to place the intraocular wiring for receiving, processing and power is difficult. With our device, the surgeon needs only to create a small pocket beneath the retina and then slip the photovoltaic cells inside it," said Jim Loudin Daniel Palanker, study co-author from the Stanford University. "The implant is thin and wireless and so is easier to implant. Since it receives information on the visual scene through an infra-red beam projected through the eye, the device can take advantage of natural eye movements that play a crucial role in visual processing," added Mathieson, according to a Strathclyde and Stanford statement. AMD results in a loss of vision in the centre of the visual field (the macula) because of damage to the retina. It occurs in "dry" and "wet" forms. This condition can make it difficult or impossible to read or recognize faces, although enough peripheral vision remains to allow other activities of daily life.