Posts tagged vision
Articles and news from the latest research reports.
Back in 2004, I was awakened early one morning by a loud clatter. I ran outside, only to discover that a car had smashed into the corner of my house. As I went to speak with the driver, he threw the car into reverse and sped off, striking me and running over my right foot as I fell to the ground. When his car hit me, I was wearing a computerized-vision system I had invented to give me a better view of the world. The impact and fall injured my leg and also broke my wearable computing system, which normally overwrites its memory buffers and doesn’t permanently record images. But as a result of the damage, it retained pictures of the car’s license plate and driver, who was later identified and arrested thanks to this record of the incident.
Was it blind luck (pardon the expression) that I was wearing this vision-enhancing system at the time of the accident? Not at all: I have been designing, building, and wearing some form of this gear for more than 35 years. I have found these systems to be enormously empowering. For example, when a car’s headlights shine directly into my eyes at night, I can still make out the driver’s face clearly. That’s because the computerized system combines multiple images taken with different exposures before displaying the results to me.
I’ve built dozens of these systems, which improve my vision in multiple ways. Some versions can even take in other spectral bands. If the equipment includes a camera that is sensitive to long-wavelength infrared, for example, I can detect subtle heat signatures, allowing me to see which seats in a lecture hall had just been vacated, or which cars in a parking lot most recently had their engines switched off. Other versions enhance text, making it easy to read signs that would otherwise be too far away to discern or that are printed in languages I don’t know.
Believe me, after you’ve used such eyewear for a while, you don’t want to give up all it offers. Wearing it, however, comes with a price. For one, it marks me as a nerd. For another, the early prototypes were hard to take on and off. These versions had an aluminum frame that wrapped tightly around the wearer’s head, requiring special tools to remove.
Steve Mann: My “Augmediated” Life - What I’ve learned from 35 years of wearing computerized eyewear
Holographic Technique Could Lead to Bionic Vision
Researchers led by biomedical engineering Professor Shy Shoham of the Technion-Israel Institute of Technology are testing the power of holography to artificially stimulate cells in the eye, with hopes of developing a new strategy for bionic vision restoration.
Computer-generated holography, they say, could be used in conjunction with a technique called optogenetics, which uses gene therapy to deliver light-sensitive proteins to damaged retinal nerve cells. In conditions such as Retinitis Pigmentosa (RP) - a condition affecting about one in 4000 people in the United States - these light-sensing cells degenerate and lead to blindness.
“The basic idea of optogenetics is to take a light-sensitive protein from another organism, typically from algae or bacteria, and insert it into a target cell, and that photosensitizes the cell,” Shoham explained.
Intense pulses of light can activate nerve cells newly sensitized by this gene therapy approach. But Shoham said researchers around the world are still searching for the best way to deliver the light patterns so that the retina “sees” or responds in a nearly normal way.
The plan is to someday develop a prosthetic headset or eyepiece that a person could wear to translate visual scenes into patterns of light that stimulate the genetically altered cells.
In their paper in the February 26 issue of Nature Communications, the Technion researchers show how light from computer-generated holography could be used to stimulate these repaired cells in mouse retinas. The key, they say, is to use a light stimulus that is intense, precise, and can trigger activity across a variety of cells all at once.
The Amazing Story Of The $300 Glasses That Correct Colorblindness
Mark Changizi and Tim Barber turned research on human vision and blood flow into colorblindness-correcting glasses you can buy on Amazon. Here’s how they did it.
About 10 years ago, Mark Changizi started to develop research on human vision and how it could see changes in skin color. Like many academics, Changizi, an accomplished neurobiologist, went on to pen a book. The Vision Revolution challenged prevailing theories—no, we don’t see red only to spot berries and fruits amid the vegetation—and detailed the amazing capabilities of why we see the way we do.
If it were up to academia, Changizi’s story might have ended there. “I started out in math and physics, trying to understand the beauty in these fields,” he says, “You are taught, or come to believe, that applying something useful is inherently not interesting.”
Not only did Changizi manage to beat that impulse out of himself, but he and Tim Barber, a friend from middle school, teamed up several years ago to form a joint research institute. 2AI Labs allows the pair to focus on research into cognition and perception in humans and machines, and then to commercialize it. The most recent project? A pair of glasses with filters that just happen to cure colorblindness.
Changizi and Barber didn’t set out to cure colorblindness. Changizi just put forth the idea that humans’ ability to see colors evolved to detect oxygenation and hemoglobin changes in the skin so they could tell if someone was scared, uncomfortable or unhealthy. “We as humans blush and blanche, regardless of overall skin tone,” Barber explains, “We associate color with emotion. People turn purple with anger in every culture.” Once Changizi fully understood the connection between color vision and blood physiology, Changizi determined it would be possible to build filters that aimed to enhance the ability to see those subtle changes by making veins more or less distinct—by sharpening the ability to see the red-green or blue-yellow parts of the spectrum. He and Barber then began the process of patenting their invention.
When they started thinking about commercial applications, Changizi and Barber both admit their minds went straight to television cameras. Changizi was fascinated by the possibilities of infusing an already-enhanced HDTV experience with the capacity to see colors even more clearly.
“We looked into cameras photo receptors and decided that producing a filter for a camera would be too difficult and expensive,” Barber says. The easiest possible approach was not electronic at all, he says. Instead, they worked to develop a lens that adjusts the color signal that hits the human eye and the O2Amp was born.
A wirelessly controlled microchip has restored limited vision to patients in a small experimental trial, report researchers in the Proceedings of the Royal Society B.
The German medical technology company Retina Implant developed the artificial retina, which was implanted in one eye of each participant as part of a company-funded trial. The patients had all been blinded by retinitis pigmentosa or another inherited disease that cause the eye’s light-detecting rod and cone cells, called photoreceptors, to degenerate and die over time. In theory, the device could also benefit patients with degenerative eye diseases such as macular degeneration, says Katarina Štigl, a clinical scientist and ophthalmologist at the University of Tübingen, who led the study.
With the implant, eight of the nine patients in the trial could perceive light. Five were able to detect moving patterns on a screen as well as everyday objects such as cutlery, doorknobs, and telephones. Three were able to read letters. Seeing their own hands and the faces of their loved ones had the biggest impression on the patients, says Štigl. “The very personal things, such as if a mouth is smiling, or the shape of a nose, are the most exciting for them,” she says.
The implanted device consists of a three-millimeter-square chip with 1,500 pixels. Each pixel contains a photodiode, which picks up incoming light, and an electrode and an amplification circuit, which boosts the weak electrical activity given off by the diode. A thin cable that runs through the eye socket connects the implant to a small coil implanted under the skin behind the ear, which means most of the system is invisible. The coil under the skin is powered by an external battery pack that can be held behind the ear with magnets.
The results follow an announcement earlier this week from California-based Second Sight that its Argus II system was approved for use in the United States. The two technologies take different approaches to restoring vision in patients with retinal degeneration. In Second Sight’s system, a camera mounted on eyeglasses picks up images that are converted into electrical signals by a small wearable computer. That data is then sent to a 60-electrode chip to stimulate neurons in the retina. The Retina Implant device instead attempts to directly replace the lost photoreceptors, allowing the remaining retinal circuitry to do the data processing.
Our primitive reflexes may be more sophisticated than they appear
Supposedly ‘primitive’ reflexes may involve more sophisticated brain function than previously thought, according to researchers at Imperial College London.
The vestibular-ocular reflex (or VOR), common to most vertebrates, is what allows us to keep our eyes focused on a fixed point even while our heads are moving. Up until now, scientists had assumed this reflex was controlled by the lower brainstem, which regulates eating, sleeping and other low-level tasks.
Researchers at Imperial’s Division of Brain Sciences conducted tests to examine this reflex in left- and right-handed subjects, revealing that handedness plays a key role in the way it operates. This suggests that higher-level functions in the cortex, which govern handedness, are involved in the control of primitive reflexes such as the VOR.
The research, published in the Journal of Neuroscience, involved seating volunteers in a motorised chair which was then spun around at a speed of one revolution every four seconds. This allowed the experimenters to study the VOR by measuring the time it took for the eyes to adjust to the spinning motion. The subjects were then presented with what are known as bistable visual phenomena, optical illusions which appear to flip between two images. Famous examples include the duck which resembles a rabbit, and the cube outline which appears to come out of and go into the page simultaneously.
Scientists already know that this bistable perception is controlled by a part of the cortex which governs more complex, decision-based tasks. Because of this, researcher Qadeer Arshad and his colleagues did not expect to find any link between the two processes.
They were surprised to find that processing bistable phenomena disrupted people’s ability to stabilise their gaze, following rightward rotation in right handers and leftward rotation in left handers. Arshad said “This is the first time that anything of this kind has been shown. Up until now, the vestibular-ocular reflex was considered a low-level reflex, not even approaching higher-order brain function. Now it seems that this primitive reflex was specialised into the cortex, the part of the brain which governs our sense of direction.”
This study could help scientists understand why some people become dizzy through experiencing purely visual stimuli, such as flickering lights or busy supermarket aisles. Professor Adolfo Bronstein, a co-author on the paper, said “Most causes of dizziness start with an inner ear - or vestibular - disorder but this initial phase tends to settle quite rapidly. In some patients, however, dizziness becomes a problematic long term problem and their dizziness becomes visually induced. The experimental set-up we used would be ideally suited to help us understand how visual stimuli could lead to long-term dizziness. In fact, we have already carried out research at Imperial around using complex visual stimuli to treat patients with long-term dizziness”
(Source: www3.imperial.ac.uk)
Brain plasticity
Babies’ brains are highly plastic, meaning they’re constantly adapting as they learn and respond to the world and people around them.
Daphne Maurer, director of the Visual Development Laboratory at McMaster University in Hamilton, Ontario, has found clues as to when plasticity might be locked off in babies and how in some adults it actually may persist unbeknown to them.
Queen’s University study aims to use stem cells to help save sight of diabetes sufferers
Scientists at Queen’s University Belfast are hoping to develop a novel approach that could save the sight of millions of diabetes sufferers using adult stem cells.
Currently millions of diabetics worldwide are at risk of sight loss due to a condition called Diabetic Retinopathy. This is when high blood sugar causes the blood vessels in the eye to become blocked or to leak. Failed blood flow harms the retina and leads to vision impairment and if left untreated can lead to blindness.
The novel REDDSTAR study (Repair of Diabetic Damage by Stromal Cell Administration) involving researchers from Queen’s Centre for Vision and Vascular Science in the School of Medicine, Dentistry and Biomedical Sciences, will see them isolating stem cells from donors, expanding them in a laboratory setting and re-delivering them to a patient where they help to repair the blood vessels in the eye. This is especially relevant to patients with diabetes were the vessels of the retina become damaged.
At present there are very few treatments available to control the progression of diabetic complications. There are no treatments which will improve glucose levels and simultaneously treat the diabetic complication.
The €6 million EU funded research is being carried out with NUI Galway and brings together experts from Northern Ireland, Ireland, Germany, the Netherlands, Denmark, Portugal and the US.
Professor Alan Stitt, Director of the Centre for Vision and Vascular Science in Queen’s and lead scientist for the project said: “The Queen’s component of the REDDSTAR study involves investigating the potential of a unique stem cell population to promote repair of damaged blood vessels in the retina during diabetes. The impact could be profound for patients, because regeneration of damaged retina could prevent progression of diabetic retinopathy and reduce the risk of vision loss.
“Currently available treatments for diabetic retinopathy are not always satisfactory. They focus on end-stages of the disease, carry many side effects and fail to address the root causes of the condition. A novel, alternative therapeutic approach is to harness adult stem cells to promote regeneration of the damaged retinal blood vessels and thereby prevent and/or reverse retinopathy.”
“This new research project is one of several regenerative medicine approaches ongoing in the centre. The approach is quite simple: we plan to isolate a very defined population of stem cells and then deliver them to sites in the body that have been damaged by diabetes. In the case of some patients with diabetes, they may gain enormous benefit from stem cell-mediated repair of damaged blood vessels in their retina. This is the first step towards an exciting new therapy in an area where it is desperately needed.”
The research focuses on specific adult stem-cells derived from bone-marrow. Which are being provided by Orbsen Therapeutics, a spin-out from the Science Foundation Ireland-funded Regenerative Medicine Institute (REMEDI) at NUI Galway.
The project will develop ways to grow the bone-marrow-derived stem cells. They will be tested in several preclinical models of diabetic complications at centres in Belfast, Galway, Munich, Berlin and Porto before human trials take place in Denmark.
Further information on the Centre for Vision and Vascular Science at Queen’s is available online at http://www.qub.ac.uk/research-centres/CentreforVisionandVascularScience/
Vision restored with total darkness
Restoring vision might sometimes be as simple as turning out the lights. That’s according to a study reported on February 14 in Current Biology, a Cell Press publication, in which researchers examined kittens with a visual impairment known as amblyopia before and after they spent 10 days in complete darkness.
Researchers Kevin Duffy and Donald Mitchell of Dalhousie University in Canada believe that exposure to darkness causes some parts of the visual system to revert to an early stage in development, when there is greater flexibility.
"There may be ways to increase brain plasticity and recover from disorders such as amblyopia without drug intervention," Duffy says. "Immersion in total darkness seems to reset the visual brain to enable remarkable recovery."
Amblyopia affects about four percent of the general population and is thought to develop when the two eyes do not see equally well in early life, as the connections from the eyes to visual areas in the brain are still being refined. Left untreated, that imbalance of vision can lead to permanent vision loss.
In the new study, the researchers examined kittens with amblyopia induced by experimentally depriving them of visual input to one eye. After those animals were plunged into darkness, their vision made a profound and rapid recovery. Further examination suggested that the restoration of vision depends on the loss of neurofilaments that hold the visual system in place. With those stabilizing elements gone, the visual system becomes free to correct itself.
Darkness therapy holds promise for the treatment of children with amblyopia, the researchers say, but don’t try this at home. They think that the darkness must be absolute to work, with no stray light at any time. It is also important to address the original cause of the amblyopia first, and to ensure that a period of darkness will not harm an individual’s good eye.
The researchers are still working out just how much darkness is required, and for how long. Regardless, they say it is unlikely that a drug could ever adequately mimic the effects of darkness that they’ve seen.
"The advantage of a simple nonpharmacological sensory manipulation, such as a period of darkness, is that it may initiate changes in a constellation of molecules in a beneficial temporal order and in appropriate brain regions," they write.
Birds evolved ultraviolet vision several times
Ultraviolet vision evolved at least eight times in birds from a common violet sensitive ancestor finds a study published in BioMed Central’s open access journal BMC Evolutionary Biology. All of these are due to single nucleotide changes in the DNA.
Modern daytime birds either have violet sensitive or ultraviolet sensitive vision. Being ultraviolet sensitive alters visual cues used to select a mate, avoiding predators, and in finding food. Researchers from Uppsala University and the Swedish University of Agricultural Sciences sequenced the genes responsible for producing the light sensitive pigment (SWS1 opsin) from 40 species of birds, in 29 families.
Generating a phylogenetic tree from these sequences shows that there have been at least 14 shifts between violet and ultraviolet sensitive colour vision and back. An ancestor of Passeriformes (perching birds including larks, swallows, blackbirds, finches, birds of paradise, and crows) and Psittaciformes (parrots and allies) changed from the ancestral violet sensitive colour vision to ultraviolet and, in some cases passerines have reverted back to violet vision.
Anders Ödeen and Olle Håstad, who performed this research commented, “There are two different amino acid alterations that can each change bird colour vision from violet to ultraviolet. One particular single nucleotide change has occurred at least 11 separate times. In general during evolution once a colour shift has occurred all species from this ancestor keep it meaning that the rest of the eye and physiology, must also evolved to ‘cement’ in the new colour sensitivity.”
(Image: webexhibits.org)
Breakthrough: New lenses cure colour blindness
Scientists have developed glasses with purple-tinged lenses that enhance reds and greens, allowing those with the most common form of the condition to see them properly.
One tester of the Oxy-Iso lenses has told how he “shivered with excitement” after putting on the glasses for the first time. Dr Daniel Bor, an academic from the University of Sussex, said: “The main thing I have problems with is when people use red and green on graphs in seminars and I can’t tell the difference between them.
"And there’s my occasionally weird dress sense, which my wife puts me right on. But putting on the glasses for the first time was really quite an exciting moment. I was with my daughter in the gym and suddenly her lips stood out.
"She was wearing a red-orange jumper and suddenly it stood out from the surroundings."
The glasses, which were originally developed for medical use, are the brainchild of US scientist Mark Changizi. The lenses filter out bands of light that interfere with the ability to distinguish various shades of red and green.
Dr Changizi, of Idaho firm 2AI Labs, said: “It makes it so they can suddenly see red-green differences in the world which were originally too small for them to notice.”
Wearing the glasses, Dr Bor managed to pass the colour blindness test used in schools around the world. However, they were not without their drawbacks. He said: “My daughter’s baby monitor has a yellow light on it and normally I can see that. But with the glasses on, it was completely invisible.
"Without the glasses, nothing is invisible. It was a bit disturbing that some things disappeared out of my vision.
"I wouldn’t wear them all the time but if I was going to an art gallery or a flower show, I’d take them with me. I’d really welcome them then."
The glasses only work for red-green colour blindness. This is the most common form and although rare in women, it affects up to 8 per cent of men. You can pick up a pair on Amazon from $297.