Nanotechnology Eye Implant Could Help to Restore Sight

Engineers from the University of California, San Diego and Nanovision Biosciences Inc., a start-up based in Southern California, have developed technology that is one step closer to helping millions of people suffering from neurodegenerative diseases that affect eyesight.

The technology blends nanotechnology and wireless electronics into a new type of retinal implant that has the ability to respond to light in the retina. The engineers demonstrated how the technology responds to light in a rat retina with a prototype device.

An array of optoelectronics nanowires interact with cortical neurons in a retina prosthesis. Source: UC San DiegoVision diseases such as macular degeneration, retinitis pigmentosa, and loss of vision due to diabetes are problems that impact millions of people worldwide. Treatment options today help regain functional vision but still severely limits patients leaving them legally blind in most cases.

 Primary cortical neurons cultured on the surface of an array of optoelectronic nanowires. Here a neuron is pulling the nanowires, indicating the the cell is doing well on this material. 

Primary cortical neurons cultured on the surface of an array of optoelectronic nanowires. Here a neuron is pulling the nanowires, indicating the the cell is doing well on this material. 

 

The engineers went about looking at crafting a new class of devices that would dramatically improve vision. The prototype prosthesis consists of arrays of silicon nanowires that simultaneously sense light and electrically stimulate the retina accordingly. The nanowires improve the resolution in the prosthesis while a wireless device transmits power and data to the nanowires over a wireless link.

Engineers tout that their development does not require a vision sensor outside of the eye to capture a visual scene and transform it into alternating signals to stimulate retinal neurons. Instead, the silicon nanowires mimic the retina’s light-sensing cones and rods to stimulate retinal cells. This makes for a simpler yet scalable architecture for the retinal prosthesis, engineers say.

“To restore functional vision, it is critical that the neural interface matches the resolution and sensitivity of the human retina,” said Gert Cauwenberghs, a professor of bioengineering at the Jacobs School of Engineering at UC San Diego.

How It Works

To power the prosthesis, power is delivered wirelessly from outside the body to the implant through an inductive powering telemetry system. The device is energy efficient because it minimizes energy losses in wireless power and data transmission and then recycles electrostatic energy within the inductive resonant tank during the stimulation process.

Engineers say up to 90 percent of the energy that is transmitted is actually delivered and used in stimulation resulting in less RF wireless power emitting radiation in the transmission and less heat being generated in the surrounding tissue.

When testing the device, engineers inserted the wirelessly powered nanowire device in rat retina resulting in the degenerated retina interfacing with the microelectrode array. The device then activated when a combination of light and electrical potential was exposed and went silent when either light or electrical bias was absent. This confirmed the light-activated and voltage-controlled response of the nanowire prosthesis.

Engineers are currently testing the device on animals and the goal is to translate their findings for clinical use to restore vision in patients with severe retinal degeneration.