Novel nano-implant may help restore sight

Scientists have developed a high-resolution retinal prosthesis using nanowires and wireless electronics that may aid neurons in the retina to respond to light.

The technology could help tens of millions of people worldwide suffering from neurodegenerative diseases that affect eyesight, including macular degeneration, retinitis pigmentosa and loss of vision due to diabetes.

In the study, detailed in the Journal of Neural Engineering, the researchers demonstrated this response to light in a rat retina interfacing with a prototype of the device in vitro.

"We want to create a new class of devices with drastically improved capabilities to help people with impaired vision," said Gabriel A. Silva, Professor at the University of California San Diego in the US.

The new prosthesis relies on two ground-breaking technologies. One consists of arrays of silicon nanowires that simultaneously sense light and electrically stimulate the retina accordingly.

The nanowires give the prosthesis higher resolution than anything achieved by other devices -- closer to the dense spacing of photoreceptors in the human retina.

The other is a wireless device that can transmit power and data to the nanowires over the same wireless link at record speed and energy efficiency. Further, the new system does not require a vision sensor outside of the eye to capture a visual scene and then transform it into alternating signals to sequentially stimulate retinal neurons.

Instead, the silicon nanowires mimic the retina's light-sensing cones and rods to directly stimulate retinal cells. Nanowires are bundled into a grid of electrodes, directly activated by light and powered by a single wireless electrical signal.

The power provided to the nanowires from the single wireless electrical signal gives the light-activated electrodes their high sensitivity while also controlling the timing of stimulation.