Nearly five years ago in my very first Vision Tech article, Four Emerging Vision-Enhancing Technologies, I reported on the Implantable Miniature Telescope from VisionCare, Inc. The device is perfectly described in its name. It's a tiny telescope that's implanted beneath the cornea that focuses vision so individuals with AMD can make greater use of their remaining peripheral vision. As part of that article, I spoke with retired engineer Dan Dunbar, who received his device in November of 2011. Dan is an avid model train enthusiast, 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. Eventually he could no longer see, he could only hear his trains as they circled the far side of his eight-by-thirty-foot O-gauge layout. Happily, the last time I spoke with Dan he was not only able to enjoy his trains again, he had returned to skiing. He was also able to return to using a computer with magnification. Here's where things get interesting.

During our conversation Dan described an unusual occurrence he experienced when he first returned to using a computer:

Something I didn't understand when it started out is that a person's sight—when you look at something and say, "oh, that's a pretty flower," or "I recognize that individual," or whatever it is you're looking at, when you actually see it in your mind, when you have this image, it's a memory. It's not necessarily what comes from the eye. It's managed vision, is the best way I can describe it.

I've worked on Mac computers since they started making them. We're on QuickBooks, and when my bookkeeper moved I started using QuickBooks online and it worked great. And now, every now and then, QuickBooks has an update. One time before I got on, it told me it wanted to update, and I said OK. …Pretty soon …it said it was OK now to open the program. I clicked Open and I had a blank, white screen. There was no object on that screen except the cursor. I kept moving the cursor around, and I could see the cursor, so I knew the display was working, but there was nothing else. I opened a different report, again, nothing.

What's going on here? They screwed up, I figured. So, I called into tech support, and I reach a young lady and she says no, we don't have any problems like that. Let me take your computer and make sure things are OK. So, I gave her the control, and she came back to me and said ?It's working just fine. I told her "I don't see anything. I have a blank screen with a cursor."

She told me to move the cursor to the upper left corner and tell me what you see. I did this. nothing. "Now move it to the upper right corner and tell me what you see." Again nothing. To the middle. Nothing.

She told me, "The upper left should have a magnifying glass symbol, the middle, a big plus sign, at the right looks like a gear." And the minute she said this, the entire display popped into view. And she hadn't done a thing. The updated layout was different. It didn't match my memory, so I couldn't see it.

The Circuitry of Vision

Vision involves a lot more than a functioning eyeball, optic nerve, and visual cortex. "Vision is a cognitive construction of what the world is around you," says Uday Patel, Senior Research Scientist at Second Sight Medical Products, makers of the Argus II artificial retina, and, more recently, The Orion brain implant. "There is a lot of memory and filling in of what you perceive."

It's not just the blind who don't always see what's right there in front of them. Have you ever heard of the "I Love Paris" optical illusion?

It's a famous illustration that most people misinterpret. Ask someone to read the text and most people recite, "I love Paris in the Springtime."

Actually, the text reads: "I Love Paris in the the springtime" with two "the'S." We aren't expecting to see the second "the" so often we don't see it. Just like we are likely to miss the gorilla passing his way through this game of basketball.

Out of necessity Dan had a strong memory of the Quicken screen layout. Only after his brain reconciled itself that it might look different did the new screen appear. Of course, this effect was likely enhanced by his magnified, telescopic vision.

Along with memory, signals from functioning eyes must also be processed. This processing takes place in various parts of the brain, and, according to Patel, "there is a lot of evidence that the circuitry for the visual cortex actually depends on early vision to wire itself correctly."

Some of this wiring is just now becoming known. Recently, for example, the news was filled with stories of Scottish native Milena Canning, who was left blind 18 years ago after a respiratory infection, a series of strokes, and an 8-month coma.

About six months after emerging from her coma Canning reported seeing a flash of reflection glinting off a metallic gift bag, "like fireworks." Soon she was able to follow a moving arm, and name the colors of large moving objects, though stationary objects remained invisible to her.

"She can see rainwater running down a window but cannot see through it," Glasgow ophthalmologist Gordon Dutton wrote in a 2003 paper. "When her daughter is walking away from her, she can see her daughter's pony tail moving from side to side but cannot see her daughter. She can see the movement of the water going down the plug hole, but she cannot see her child in the bath."

Dutton referred Canning to the Western University's Brain and Mind Institute in London, Ontario, where cognitive neuroscientist Jody Culham and a team of researchers performed a series of tests, including a full functional MRI.

"Canning is missing a piece of brain tissue about the size of an apple at the back of her brain—almost the entirety of her occipital lobes," Culham and her team members discovered. "However, there is an area, just at the edge of the part that's damaged—about a teaspoon on each side—that survived intact. This area, known as the MT for Middle Temporal, activates whenever someone sees movement.

"In Milena's case, we think the 'super-highway' for the visual system reached a dead end. But rather than shutting down her whole visual system, she developed 'back roads' that could bypass the damaged pathways to bring some vision—especially motion—to other parts of the brain."

The condition is known as Riddoch syndrome, or the Riddoch phenomenon, also known as statokinetic dissociation—where someone who is otherwise blind can see moving objects.

The opposite condition also exists. It's called akinetopsia and these patients have a damaged MT, and are left viewing the entire world as a series of still images.

"Sort of like what a person with normal vision might see in a room where a strobe light has been switched on," says Culham.

Persons with akinetopsia have trouble knowing when a drinking glass is about to overflow, and are probably the last to be picked in a game of beach volleyball or motorcycle racing, though Culham did relate she once knew of a man with akinetopsia who drove a motorcycle regularly.

Facial Recognition

Another aspect of vision that most experts agree is learned early in life is the ability to recognize faces. Some people grow up lacking this ability. It's known as face blindness or developmental prosopagnosia (DP) and among its sufferers was the famed British neurologist Oliver Sacks, author of The Man Who Mistook His Wife for a Hat and other ground-breaking works that diagnosed and described unusual brain anomalies.

In a 2010 New Yorker article entitled "Face-Blind" he wrote:

At the age of seventy-seven, despite a lifetime of trying to compensate, I have no less trouble with faces and places. I am particularly thrown if I see people out of context, even if I have been with them five minutes before. This happened one morning just after an appointment with my psychiatrist. (I had been seeing him twice weekly for several years at this point.) A few minutes after I left his office, I encountered a soberly dressed man who greeted me in the lobby of the building. I was puzzled as to why this stranger seemed to know me, until the doorman greeted him by name—it was, of course, my analyst. (This failure to recognize him came up as a topic in our next session; I think that he did not entirely believe me when I maintained that it had a neurological basis rather than a psychiatric one.)

Reports of prosopagnosia date back centuries, although it wasn't until 1947 that the condition was officially recognized. Until recently it was thought there were only a few hundred face-blind individuals in the world, but recent studies at Harvard and University College London have discovered that up to two percent of the population may have some degree of face-blindness.

In his New Yorker article, Sacks also describes how he has to ride his bike along the same route every day because otherwise he will get lost.

This, too, is not unusual, as at least one recent study has demonstrated that the inability to recognize faces is linked to broader visual recognition problems.

"Our research indicates that neural abnormalities in many people with DP are more widespread than previous studies have suggested," says psychology and brain sciences professor Bradley Duchaine, the principal investigator of the Social Perception Lab at Dartmouth College. The study he refers to included 22 people with DP and 25 control subjects. Each were shown videos that included faces, objects, and scenes. Those with DP tended to respond less strongly than the control subjects in brain areas associated with facial recognition, but also less strongly in areas associated with scene recognition.

The takeaway here is that while previously it was thought that DP was caused by a lack of experience with faces, it's more likely a result of a broader neurobiological cause affecting a broad region of the cortex.

Mind Blindness

One of the most unusual "vision" problems I encountered researching this article has nothing at all to do with actual eyesight. It's called mind blindness, or congenital aphantasia. It's the inability to form any sort of mental images. According to recent estimates between two and five percent of the population may experience this condition.

In a recent interview with Australia's news channel nin.com.au, 22-year-old recent graduate Maddie Burrows described her experience of the condition: "When I try to really visualize someone's face, really I'm just thinking about how there is nothing there. But I still have so much information about what their face looks like, I just can't bring the image together. When I think about whether it's a round or narrow face and if they have brown or blonde hair, all of that detail I still know, I just can't put it into an image."

In her interview, Burrows stated that her problems weren't limited to picturing faces. She also has trouble imagining anything at all. She can't picture her home, her bedroom, or even simple shapes like a circle or square.

Later in the interview Burrows stated that her mind blindness makes it difficult for her to do math in her head. "Another negative is that I'm not the best at navigation and direction. If I am walking to a place that I've been to a million times before I don't need to think about it. But if it's a place I only vaguely know I need to remember street names and building names."

Mental calculations and navigation. Hmmm.

The Future of Vision Tech

With all the groundbreaking research and development on artificial retinas, brain implants, stem cell patches, and even the possibility of whole-eye transplant, it's important for us to remember vision involves a lot more than sending and receiving pixels. "There is no little man inside your head watching TV," says Culham.

What will happen when someone blind since birth undergoes a successful whole-eye transplant or stem cell retinal replacement at the age of 30? Will he or she ever be able to distinguish letters of the alphabet without touching them and a lot of training? What about that same person, only he or she went blind at 12 years of age? The average length of time a person has been blind before receiving an Argus II retinal implant is 20 years. Will someone who has been blind for 50 years do better than someone blind for only 2 years? Would it be possible to perform brain scans to determine likely success rates before the blind individual undergoes complex surgery? How much do mental calculations and orientation depend on creating a workable mental image, and are there ways to improve a blind person's ability to do this? Are there better ways to stimulate the brain with the tiny electrodes of an ocular bypass system such as the Argus?

Happily, we are living in times when answers to these and other similar questions may come from science rather than science fiction.

This article is made possible in part by generous funding from the James H. and Alice Teubert Charitable Trust, Huntington, West Virginia.

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Author
Bill Holton
Article Topic
Vision Research