[Nfbf-l] Four Emerging Vision-Enhancing Technologies

[Alan Dicey]

>From September Issue of AccessWorld
AFB American Foundation for the Blind
Vision Research
Four Emerging Vision-Enhancing Technologies: the Implantable Miniature 
Telescope, the Telescopic Contact Lens, the Argus II Retinal Prosthesis, and 
the Artificial Silicon Retina
Bill Holton

The first television sets had screens barely larger than a postage stamp and 
were housed in bulky, console cabinets. Nowadays a 60-inch high-definition 
flatscreen can hang from your wall like a painting. We've certainly come a 
long way from the first wireless phones that were so large you needed a 
briefcase, or at the very least a bag, to carry one around.

Even our low-vision aids have benefited from the trend of "make it better, 
make it smaller." The first video enlargers and OCR reading machines often 
occupied an entire desktop. Today you can carry a substantially more 
powerful unit in your pocket. And is there anyone who would even consider 
lugging around a 10-year-old braille display to use with one of today's 
super-slim accessible cell phones?

Low vision technology solutions can help the visually impaired get the most 
use from limited vision, and these days the technologies have grown so small 
and powerful, you might not even have to carry them around with you. They're 
always on and always with you, because they work from right on top of, or 
even inside of, the eye itself.

In this article we'll take a look at four emerging technologies with the 
potential to enhance the useable vision of many individuals with age-related 
macular degeneration (AMD) and retinitis pigmentosa (RP). Three of them, the 
Implantable Miniature Telescope, the Argus II and Retinal Prosthesis System, 
and the Artificial Silicon Retina microchip (ASR) do at least a portion of 
their work from inside the eye. The fourth, an experimental telescopic 
contact lens, uses tiny mirrors to magnify and redirect images around 
damaged retinal tissue.

The Implantable Miniature Telescope
Monoculars and other magnification aids can be extremely useful to many 
individuals with partial vision. But imagine if you didn't have to remember 
to carry one with you, because it was always with you. That was the thinking 
behind the Implantable Miniature Telescope from VisionCare Ophthalmic 
Technologies. The device is no larger than a pea, and to date, nearly 400 
individuals with end-stage age-related macular degeneration have received 
implants with a useable-vision success rate of over seventy-five percent.

How it Works
Macular degeneration damages the retina from the center out. As the sharper 
central vision is destroyed, people with AMD must increasingly rely on their 
peripheral vision, which is not nearly so adept at reading text, recognizing 
faces and the like. Magnification can help, which is where the Implantable 
Miniature Telescope comes in.

Recipients of the telescope undergo surgery similar to cataract removal. The 
natural lens of the eye is replaced with a small, one-piece, 2.75 
magnification telescope. The device projects a magnified image onto the 
retina, which enables the peripheral vision to resolve significantly finer 
detail, such as print or faces.

"It took me several months to get used to seeing with the telescope," says 
retired engineer Dan Dunbar, who received his device in November of 2011. 
Dan, now 82, is a long time model train hobbyist, but by the early 2000s he 
had worked his way up the size scale from N-gauge through HO-gauge all the 
way up to O-gauge model trains to accommodate his lessening vision. 
Eventually he could no longer see his trains as they circled the far side of 
his eight-by-thirty-foot O-gauge layout.

After his surgery Dan underwent several months of eye exercises with a 
low-vision specialist. He was also fitted for a pair of glasses with a 
prescription lens for his left eye, which had the implanted telescope. The 
telescope is one-size-fits-all, but retinas are not. A corrective lens is 
usually also required to adjust the focus so it strikes the retina at the 
ideal focal point, much the same as prescription lenses do for nearsighted 
or farsighted individuals.

"At first, everything looked sort of muddy out of that eye," Dan recalls. 
"Then one day things just sort of clicked." There was still work to be done. 
"Doors looked larger and closer than they actually were," he says. "And I 
remember one day in the car with my wife, she made a right turn and the car 
seemed to lurch so fast, I felt like I was sitting way in the back of an 
amusement park bumper car ride."

The miniature telescope is implanted only in one eye, the better of the two. 
The other eye continues to provide peripheral vision to help with balance 
and orientation. Gradually, Dan has learned to switch his focus back and 
forth so his brain can assimilate the visual information gathered from each 
eye. "The magnified doorknob looks larger than it is, but my other eye tells 
me it's really not as close as it seems," he explains.

Enlarging the image projected onto the retina also causes the brain to 
interpret the area covered by the degenerated macula as having grown 
proportionally smaller, reducing the effect the blind spot has on central 
vision. "These days when I look someone in the eye, to me, their face seems 
dead center in my vision," Dan says, adding, "It's taken me a long time to 
get used to not having to turn my gaze to see what's in front of me."

Before his implant Dan's reading was limited to magnified text on his 
computer. Now he can slowly read the print in most paperbacks. He's also 
enjoying his trains more than ever. These days he can see them easily, even 
at the far end of the track.

The Telescopic Contact Lens
One day soon individuals with macular degeneration and others whose useable 
vision can be increased with magnification may be able to enjoy the benefits 
of an implantable telescope without having to undergo the surgery. That's 
because a team of researchers at the Jacobs School of Engineering at UC San 
Diego are developing a telescopic contact lens.

The wearable lenses are one millimeter thick, and their centers allow 
normal, non-magnified images to pass through. Within the outer edge, 
however, a collection of tiny aluminum mirrors create a ring-shaped 
telescope that magnifies images 2.8 times and helps the peripheral retina 
outside of the macula to resolve greater detail.

The lenses include polarization filters that allow light oriented in one 
direction to pass through the clear center and light oriented in another 
direction to strike the magnifying mirrors. 3D movies use special glasses to 
direct one image to the viewer's left eye and a slightly different second 
image to the right eye. These magnifying contacts will use similar glasses 
with liquid crystal shutters, only instead of sending different images to 
different eyes it will shift the polarization so it can pass through either 
the lens' clear center or the magnification mirrors, but not both.

Initially, users will flip a switch to toggle back and forth between regular 
and telescopic vision. But project leader Joe Ford and his team members are 
also working on a hands-free switch that will use an infrared LED to monitor 
when the user blinks with both eyes or winks with one eye to make the switch 
automatically.

The Argus II Retinal Prosthesis
Many individuals with little or no light perception can use light detectors 
(available either as stand-alone devices or via a number of smartphone apps) 
that can provide information about the environment, such as the position of 
doors and windows, via the location and strength of the edges between light 
and dark regions. That's the principle behind the Argus II Retinal 
Prosthesis from Second Sight Medical Products, which received FDA approval 
in February 2013 for the treatment of late-stage RP.

An inherited retinal degenerative disease, RP leads to blindness due to a 
progressive loss of the light-sensitive photoreceptor cells called rods and 
cones. Often the underlying retinal nerves are left undamaged, however, and 
the Argus II stimulates these nerves directly, bypassing the damaged rods 
and cones altogether.

The device includes an aspirin-size capsule implanted beneath the 
conjunctiva, the white of the eye, on the side nearest the temple. A tiny 
antenna receives both a wireless data signal and radio frequency power from 
outside of the eye, and then transmits these signals to a 4-by-6mm polymer 
array of 60 microscopic electrodes implanted on the retinal surface.

Argus II users wear special glasses with a miniature video camera mounted on 
the bridge. Each user also carries a Video Processing Unit (VPU) about the 
size of a deck of cards on his or her waist. The VPU powers the camera, 
processes the camera's video signal and then sends it back to the glasses, 
where a second, external antenna communicates with the implant from directly 
outside the eye.

Kathy Blake received the very first Argus II implant in a clinical trial in 
June 2007. Technicians spent several months activating the electrodes one by 
one, fine tuning the electrical current going to each so it was strong 
enough to trigger a response without being overwhelming.

"Gradually, I began sensing edges," says Kathy. "I would move my head from 
side to side, panning the camera, and when I scanned past a window, say, I 
would see a brief flash of contrast. In time, Kathy's ability to detect 
edges increased, along with her ability to sense the contrast in different 
shades of gray. "If I sit at the table and move my head side to side to pan 
the camera I can tell where the silverware is, and the difference between my 
plate and napkin," she says. "Walking with my guide dog, I can see the 
crosswalks, and if she stops and sits I can close my eyes to concentrate, 
scan ahead, and deduce, 'Oh, that's a car blocking the sidewalk.'"

The Video Processing Unit includes three special settings that can be 
customized for, and selected by, each user. In Kathy's case, the first is an 
invert mode that makes bright items dark and dark items bright, which Kathy 
uses outdoors so the bright sunlight doesn't cause everything to flash too 
bright. A contrast enhancement setting helps in dim light, and with this 
setting Kathy was able to pick out the lights on last year's Christmas tree. 
She can also sort her laundry, lights from darks, and match socks by placing 
items one by one against a white background. The third setting enhances edge 
detection, but, reports Kathy, "That one doesn't seem to make any difference 
for me."

Kathy uses the system for at least 15 to 20 hours every week. She's 
extremely satisfied with the results, but she's never expected miracles. 
"Mostly, I did it to participate in the research and maybe help things 
along," she says. Indeed, company scientists have used what they've learned 
from Kathy and other early implant recipients to continue to improve the 
device. Many recent recipients are able to perceive rudimentary colors. 
Others can distinguish letters less than an inch high without having to pan 
their cameras at all.

The Argus I used only 16 electrodes. The Argus II uses 60, and the company 
is planning to use even more in future versions. They have also begun 
tentative experiments with virtual electrodes, altering the signals in order 
to stimulate the retina between the electrodes, much as a stereo generates 
sound that seems to come from the far left, right, center or anywhere 
in-between.

The Artificial Silicon Retina
These days a growing number of low-vision aids contain at least one computer 
chip. Here's one that consists of a single slice of silicon.

The Artificial Silicon Retina (ASR) is a tiny computer chip, 2mm wide and 
one-third the thickness of a human hair, which is implanted in a surgically 
created sub-retinal pocket. The ASR contains approximately five thousand 
microphotodiodes, which are tiny solar cells that turn light into 
electricity, and then use that electricity to send extra stimulation to 
damaged rods and cones without the need for external power sources or 
glasses.

In the early 200os, Alan Chow, MD, Assistant Professor of Ophthalmology at 
Rush University, performed the first of a total of 42 ASR implants. "Over 
one-third of the recipients experienced the sensation of a light flash when 
the implant was stimulated," reports Dr. Chow. "However, all patients 
experienced an unexpected and even more important measureable improvement in 
their remaining central vision, including better perception of color, 
contrast, visual acuity and field size."

According to Chow, these improvements were more than could be explained from 
simple electrical stimulation of retinal cells. For some, the improvements 
took an unexpected, even more surprising turn.

"Not only did the vision in my right eye, the one with the implant, improve, 
the vision in my left eye also got stronger," says Melanie Furniss, a 
retired operations manager for a Fortune 500 company. Melanie has RP, and in 
2004 when she received her implant her visual field was less than 5% and she 
could only read print with the help of an electronic magnifier.

A few months post-implant, Melanie began to perceive colors again. After a 
year she was reading regular print, and able to thread a sewing needle by 
sight. And when she held a hand over her right eye, "The vision was still 
too blurry to make out letters," she says. "But there was definitely an 
improvement in my left eye as well. My retina specialist confirmed that the 
rods and cones in both eyes looked healthier."

As to why Melanie and many other implant recipients experienced this 
sympathetic response, Dr. Chow offers this theory: "The implant works by 
inducing certain retinal cells to increase their production of neurotropic 
factors. This has now been shown in a number of published animal studies" he 
explains. "These factors can circulate in the blood stream, so the opposite 
eye could also be receiving the benefits."

Unfortunately, the improvements may not be permanent. Melanie and others 
report that after five or six years their vision peaked, and though it is 
still sharper than before their implants, in recent years the improvements 
have begun to diminish.

"We are currently testing methods that might help preserve a greater degree 
and longer duration of vision," says Chow. For now, a second implant is not 
possible. The group that invested in the original ASR implants could not 
afford the more than $200 million standard FDA approval would have required. 
Dr. Chow has reorganized the project, however, and this time he is hoping to 
obtain a humanitarian device exemption, which would cost significantly less.

More Information
The Implantable Miniature Telescope
VisionCare Ophthalmic Technologies, Inc.

877-99-SIGHT (877-997-4448).

Currently the Implantable Miniature Telescope is FDA approved only for 
individuals over 75 with end-stage age-related macular degeneration. The 
good news is the device is now eligible for Medicare reimbursement.

The Telescopic Contact Lens
Currently, the telescopic contact lens is still in the research phase, and 
has only been tested on a handful of military volunteers. The group hopes to 
begin clinical trials sometime later this year, but access to a waiting list 
and further information are not available to the public at this time .

The Argus II Retinal Prosthesis
Second Sight Medical Products, Inc.

818-833-5060
The Argus II was FDA approved in February of 2013 for individuals over 25 
years old with loss of all functional vision from retinitis pigmentosa, 
though the company is planning upcoming trials for individuals with 
age-related macular degeneration. By the end of 2013 the company plans to 
offer the device in 12 medical centers. The Centers for Medicare and 
Medicaid Services has approved the device for reimbursement, and at this 
writing one private pay insurance company, Health Net, also reimburses for 
the implant.

The Artificial Silicon Retina
Optobionics

630-858-4411
Though no date has been set to resume ASR implants, several hundred people 
are currently on a waiting list to receive the device if and when it becomes 
available.


With Best Regards,
God Bless,
Alan
Plantation, Florida