Stanford varsity team finds PV implants effective in restoring sight

Retinal implant

A team led by Stanford University researchers has found photovoltaic implants effective in providing functional vision to patients with blindness caused by retinal degenerative diseases such as retinitis pigmentosa or macular degeneration.

The team claims the implant could restore vision five times better than existing devices.

They have demonstrated through sub-retinal implants in rats with such visual impairment that electrical stimulation of surviving retinal neurons provides an alternative route for the delivery of visual information.

The said implants are able to convert light transmitted from special glasses into electrical current. The current stimulates the retina’s bipolar cells.

Retinal degeneration leads to loss of sight owing to the gradual death of photoreceptors.

“We demonstrate that subretinal implants with 70-μm-wide photovoltaic pixels provide highly localized stimulation of retinal neurons in rats. The electrical receptive fields recorded in retinal ganglion cells were similar in size to the natural visual receptive fields,” a research paper published in Nature says.

“In rats with retinal degeneration, these photovoltaic arrays elicited retinal responses with a spatial resolution of 64 ± 11 μm, corresponding to half of the normal visual acuity in healthy rats,” the paper adds.

So far, the researchers have tested the device only in animals, but a clinical trial is planned next year in France.

“The performance we’re observing at the moment is very encouraging,” said Georges Goetz, a lead author of the paper and graduate student in electrical engineering at Stanford. “Based on our current results, we hope that human recipients of this implant will be able to recognize objects and move about.”

Ajith Kumar S