A bionic retina implant which registers light and transmits messages to the brain could cure degenerative blindness due to retinitis pigmentosa, according to a team of German researchers.
However, the team of scientists headed by Eberhart Zrenner at the University of Tuebingen in south-west Germany cautioned that the bionic chip inside the eyeball only works on patients who have lost their eyesight due to retina damage, not to those born blind.
The research, published in Proceedings B, the journal of the Royal Society, reveals that the researchers have developed a retinal implant that has allowed three blind people to see shapes and objects within days of the implant being installed.
One blind person was even able to identify and find objects placed on a table in front of him, as well as walking around a room independently and approaching people, reading a clock face and differentiating seven shades of grey.
The device, which has been developed by the company Retinal Implant AG together with the Institute for Ophthalmic Research at the University of Tuebingen, represents an unprecedented advance in electronic visual prostheses.
It could eventually revolutionise the lives of thousands of people worldwide who suffer from blindness as a result of retinitis pigmentosa, a degenerative eye disease. The disease causes light receptors in the eye to cease functioning. (About 1.5 million people have the disease, with progressive visual impairment.)
"The results of this pilot study provide strong evidence that the visual functions of patients blinded by a hereditary retinal dystrophy can, in principle, be restored to a degree sufficient for use in daily life," writes Zrenner, founding director of Retinal Implant AG and director and chairman of the University of Tuebingen Eye Hospital.
The device, known as a sub-retinal implant, sits underneath the retina, directly replacing light receptors lost in retinal degeneration. As such, it uses the eyes' natural image processing capabilities beyond the light detection stage to produce a visual perception in the patient that is stable and follows their eye movements.
Other types of retinal implants, known as epiretinal implants, sit outside the retina and because they bypass the intact light-sensitive structures in the eyes they require the user to wear an external camera and processor unit.
The sub-retinal implant described in this paper achieves unprecedented clarity because it has a great deal more light receptors than other similar devices.
As Zrenner states, "The present study presents proof-of-concept that such devices can restore useful vision in blind human subjects, even though the ultimate goal of broad clinical application will take time to develop."
(Sapa, December 2010)
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