[Njtechdiv] upcoming vision research

[Mario Brusco]

Vision Tech: Recent Retinal Research	
http://www.afb.org/afbpress/pubnew.asp?DocID=aw190502

by Bill Holton

Back in our very first Vision Tech article,
Four Emerging Vision-Enhancing Technologies,
(https://www.afb.org/afbpress/pubnew.asp?DocID=aw140902)

we introduced you to the Argus II artificial retina, developed by Second 
Sight Medical Products and approved by the FDA in February of 2013 for 
the treatment
of late-stage retinitis pigmentosa (RP). The Argus II uses special 
eyeglasses with a mounted camera that streams video to a small 
receiver/computer. This unit encodes the stream and sends the 
information to a retina-implanted chip, which forwards the signal 
through tiny electrodes into the optic nerve, and from there to the 
visual cortex.

In our most recent Vision Tech article, Vision Technology in Clinical 
Trial Phase: New Approaches to AMD Treatment and Sight Restoration
(http://www.afb.org/afbpress/pubnew.asp?DocID=aw181203)

from the December 2017 issue, we noted the company has now received 
permission to begin preliminary human clinical trials of a visual 
prosthesis known as Orion. Orion will use the same type of external 
glasses and processor as the Argus, but instead of sending the signal to 
a retinal chip, the signals will be delivered to the visual cortex directly.

Both of these devices (Argus and Orion) require special glasses, an 
external power supply, and a processing unit.

But what if we could do away with at least two of these? That's the 
thinking behind a new implant currently in clinical trials from the 
German company, Retina Implant AG. The device, called the RETINA IMPLANT 
Alpha AMS is also an implanted microchip, but it works on a different 
principle than the Argus.

First, to review how the Argus works: the processing unit receives a 
video stream from the eyeglass camera, then processes and interpolates 
it. This digital signal is then streamed wirelessly to the retinal chip, 
which, in turn, stimulates a layer of specialized ganglion cells. These 
cells forward the electrical signals through the optic nerve to the 
brain, and viola--vision.

"The German thinking is that we could stimulate these ganglia cells 
using normal light that enters the eye, without an external processor," 
says Dr. Samantha De Silva, Honorary Clinical Research Associate at the 
Nuffield Department of Clinical Neurosciences at Oxford University. This 
research laboratory has collaborated with Retina Implant AG in clinical 
trials of the device. "Instead of lying atop the retina, the RI Alpha 
AMS chip is placed underneath. 1,600 photodiodes are activated by the 
light, which then stimulates remaining inner retinal cells, such as 
bipolar cells, along with any still-functioning rods
and cones. These signals are passed along to the ganglia cells upon 
which they rest. Following the natural optical path, the signal is then 
transmitted
to the brain via the optic nerve, with no need for glasses, no outside 
processing--just a small power supply the user wears behind an ear."

The surgery for implantation of the subretinal chip is complex, however, 
and De Silva is researching another, simpler way to restore vision in 
damaged retinas, one that will require a more routine operation.

Interested in finding out more, visit the article link at the top of 
this article.