Blindness from some inherited eye diseases may be caused by gut bacteria

Sight loss in certain inherited eye diseases may be caused by gut bacteria, and is potentially treatable by antimicrobials, finds a new study in mice co-led by a UCL and Moorfields researcher.

The international study observed that in eyes with sight loss caused by a particular genetic mutation, known to cause eye diseases that lead to blindness, gut bacteria were found within the damaged areas of the eye.

The authors of the new paper, published in Cell and jointly led by researchers in China, say their findings suggest that the genetic mutation may relax the body's defences, thus allowing harmful bacteria to reach the eye and cause blindness.

The gut contains trillions of bacteria, many of which are key to healthy digestion. However, they can also be potentially harmful.

The researchers were investigating the impact of the Crumbs homolog 1 (CBR1) gene, which is known to be expressed in the retina (the thin layer of cells at the back of the eye) and is crucial to building the blood-retina barrier to regulate what flows in and out of the eye.

The CRB1 gene is associated with inherited eye disease, most commonly forms of Leber congenital amaurosis (LCA) and retinitis pigmentosa (RP); the gene is the cause of 10% of LCA cases and 7% of RP cases worldwide.

Using mouse models, the research team discovered the CRB1 gene is key to controlling the integrity of the lower gastrointestinal tract, the first ever such observation. There, it combats pathogens and harmful bacteria by regulating what passes between the contents of the gut and the rest of the body.

The team found that when the gene has a particular mutation, dampening its expression (reducing its effect), these barriers in both the retina and the gut can be breached, enabling bacteria in the gut to move through the body and into the eye, leading to lesions in the retina that cause sight loss.

Crucially, treating these bacteria with antimicrobials, such as antibiotics, was able to prevent sight loss in the mice even though it did not rebuild the affected cell barriers in the eye.

Inherited eye diseases are the UK's leading cause of blindness in working-age people. Onset of disease may vary from very early childhood to adulthood, but deterioration is irreversible and has lifelong implications. To date, the development of treatments has largely focused on gene therapies.

The findings of this study suggest that simply using antimicrobials might help prevent deterioration in CRB1-associated inherited eye diseases. Future work will investigate whether this applies in humans.

Co-lead author Professor Richard Lee (UCL Institute of Ophthalmology and Moorfields Eye Hospital NHS Foundation Trust) said: "We found an unexpected link between the gut and the eye, which might be the cause of blindness in some patients.

"Our findings could have huge implications for transforming treatment for CRB1-associated eye diseases. We hope to continue this research in clinical studies to confirm if this mechanism is indeed the cause of blindness in people, and whether treatments targeting bacteria could prevent blindness.

"Additionally, as we have revealed an entirely novel mechanism linking retinal degeneration to the gut, our findings may have implications for a broader spectrum of eye conditions, which we hope to continue to explore with further studies."

Read more at Science Daily

Vision via sound for the blind

Australian researchers have developed cutting-edge technology known as "acoustic touch" that helps people 'see' using sound. The technology has the potential to transform the lives of those who are blind or have low vision.

Around 39 million people worldwide are blind, according to the World Health Organisation, and an additional 246 million people live with low vision, impacting their ability to participate in everyday life activities.

The next generation smart glasses, which translate visual information into distinct sound icons, were developed by researchers from the University of Technology Sydney and the University of Sydney, together with Sydney start-up ARIA Research.

"Smart glasses typically use computer vision and other sensory information to translate the wearer's surrounding into computer-synthesized speech," said Distinguished Professor Chin-Teng Lin, a global leader in brain-computer interface research from the University of Technology Sydney.

"However, acoustic touch technology sonifies objects, creating unique sound representations as they enter the device's field of view. For example, the sound of rustling leaves might signify a plant, or a buzzing sound might represent a mobile phone," he said.

A study into the efficacy and usability of acoustic touch technology to assist people who are blind, led by Dr Howe Zhu from the University of Technology Sydney, has just been published in the journal PLOS ONE.

The researchers tested the device with 14 participants; seven individuals with blindness or low vision and seven blindfolded sighted individuals who served as a control group.

They found that the wearable device, equipped with acoustic touch technology, significantly enhanced the ability of blind or low-vision individuals to recognise and reach for objects, without causing too much mental effort.

"The auditory feedback empowers users to identify and reach for objects with remarkable accuracy," said Dr Zhu. "Our findings indicate that acoustic touch has the potential to offer a wearable and effective method of sensory augmentation for the visually impaired community."

The research underscores the importance of developing assistive technology in overcoming the challenges such as locating specific household items and personal belongings.

By addressing these day-to-day challenges, the acoustic touch technology opens new doors for individuals who are blind or have low vision, enhancing their independence and quality of life.

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Scientists achieve promising results towards restoring vision in blindness caused by cellular degeneration in the eye

A preclinical study using stem cells to produce progenitor photoreceptor cells -- light-detecting cells found in the eye -- and then transplanting these into experimental models of damaged retinas has resulted in significant vision recovery. This finding, by scientists at Duke-NUS Medical School, the Singapore Eye Research Institute and the Karolinska Institute in Sweden, marks a first step towards potentially restoring vision in eye diseases characterised by photoreceptor loss.

"Our laboratory has developed a novel method that enables the production of photoreceptor progenitor cells resembling those in human embryos," said Assistant Professor Tay Hwee Goon, first author of the study from Duke-NUS' Centre for Vision Research. "Transplantation of these cells into experimental models has yielded partial restoration of the retinal function."

The degeneration of photoreceptors in the eye is a significant cause of declining vision that can eventually lead to blindness and for which there is currently no effective treatment. Photoreceptor degeneration occurs in a variety of inherited retinal diseases, such as retinitis pigmentosa -- a rare eye disease that breaks down cells in the retina over time and eventually causes vision loss -- and age-related macular degeneration, a leading cause of vision impairment worldwide.

Asst Prof Tay and her team developed a procedure to grow human embryonic stem cells in the presence of purified laminin proteins that are involved in normal development of human retinas. In the presence of the laminins, stem cells could be directed to differentiate into photoreceptor progenitor cells responsible for converting light into signals that are sent to the brain.

When these cells were transplanted into damaged retinas, the preclinical models showed significant recovery of vision. A diagnostic test called electroretinogram also identified significant recovery in the retinas via electrical activity in the retina in response to a light stimulus. The transplanted cells established connections with surrounding retinal cells and nerves in the inner retina. They also survived and functioned for many weeks after transplantation.

Moving forward, the team hopes to refine their method to make it simpler and achieve more consistent results than earlier attempts to explore stem cell therapy for photoreceptor cell replacement.

"It is exciting to find these results, which suggest a promising route towards using stem cells to treat those forms of visual deterioration and blindness caused by the loss of photoreceptors," said Dr Helder Andre, Head of Molecular and Cellular Research from Karolinska Institute's Department of Clinical Neuroscience and a senior author of the study.

Associate Professor Enrico Petretto, Director of the Centre for Computational Biology at Duke-NUS and the study's bioinformatics analysis lead, added: "Our method may also be useful for understanding the molecular and cellular pathways that drive the progression of macular degeneration, perhaps leading to the development of other therapeutic approaches."

The next challenge for the researchers is to explore the efficacy of their method in models of photoreceptor degeneration that more closely match the human condition.

"If we get promising results in our future studies, we hope to move to clinical trials in patients," said Professor Karl Tryggvason, from Duke-NUS' Cardiovascular and Metabolic Disorders Programme, and the corresponding author of the study. "That would be an important step towards for being able to reverse damage of the retina and restore vision."

Read more at Science Daily

'Smart' walking stick could help visually impaired with groceries, finding a seat

Engineers at the University of Colorado Boulder are tapping into advances in artificial intelligence to develop a new kind of walking stick for people who are blind or visually impaired.

Think of it as assistive technology meets Silicon Valley.

The researchers say that their "smart" walking stick could one day help blind people navigate tasks in a world designed for sighted people -- from shopping for a box of cereal at the grocery store to picking a private place to sit in a crowded cafeteria.

"I really enjoy grocery shopping and spend a significant amount of time in the store," said Shivendra Agrawal, a doctoral student in the Department of Computer Science. "A lot of people can't do that, however, and it can be really restrictive. We think this is a solvable problem."

In a study published in October, Agrawal and his colleagues in the Collaborative Artificial Intelligence and Robotics Lab got one step closer to solving it.

The team's walking stick resembles the white-and-red canes that you can buy at Walmart. But it also includes a few add-ons: Using a camera and computer vision technology, the walking stick maps and catalogs the world around it. It then guides users by using vibrations in the handle and with spoken directions, such as "reach a little bit to your right."

The device isn't supposed to be a substitute for designing places like grocery stores to be more accessible, Agrawal said. But he hopes his team's prototype will show that, in some cases, AI can help millions of Americans become more independent.

"AI and computer vision are improving, and people are using them to build self-driving cars and similar inventions," Agrawal said. "But these technologies also have the potential to improve quality of life for many people."

Take a seat

Agrawal and his colleagues first explored that potential by tackling a familiar problem: Where do I sit?

"Imagine you're in a café," he said. "You don't want to sit just anywhere. You usually take a seat close to the walls to preserve your privacy, and you usually don't like to sit face-to-face with a stranger."

Previous research has suggested that making these kinds of decisions is a priority for people who are blind or visually impaired. To see if their smart walking stick could help, the researchers set up a café of sorts in their lab -- complete with several chairs, patrons and a few obstacles.

Study subjects strapped on a backpack with a laptop in it and picked up the smart walking stick. They swiveled to survey the room with a camera attached near the cane handle. Like a self-driving car, algorithms running inside the laptop identified the various features in the room then calculated the route to an ideal seat.

The team reported its findings this fall at the International Conference on Intelligent Robots and Systems in Kyoto, Japan. Researchers on the study included Bradley Hayes, assistant professor of computer science, and doctoral student Mary Etta West.

The study showed promising results: Subjects were able to find the right chair in 10 out of 12 trials with varying levels of difficulty. So far, the subjects have all been sighted people wearing blindfolds. But the researchers plan to evaluate and improve their device by working people who are blind or visually impaired once the technology is more dependable.

"Shivendra's work is the perfect combination of technical innovation and impactful application, going beyond navigation to bring advancements in underexplored areas, such as assisting people with visual impairment with social convention adherence or finding and grasping objects," Hayes said.

Let's go shopping

Next up for the group: grocery shopping.

In new research, which the team hasn't yet published, Agrawal and his colleagues adapted their device for a task that can be daunting for anyone: finding and grasping products in aisles filled with dozens of similar-looking and similar-feeling choices.

Again, the team set up a makeshift environment in their lab: this time, a grocery shelf stocked with several different kinds of cereal. The researchers created a database of product photos, such as boxes of Honey Nut Cheerios or Apple Jacks, into their software. Study subjects then used the walking stick to scan the shelf, searching for the product they wanted.

"It assigns a score to the objects present, selecting what is the most likely product," Agrawal said. "Then the system issues commands like 'move a little bit to your left.'"

He added that it will be a while before the team's walking stick makes it into the hands of real shoppers. The group, for example, wants to make the system more compact, designing it so that it can run off a standard smartphone attached to a cane.

But the human-robot interaction researchers also hope that their preliminary results will inspire other engineers to rethink what robotics and AI are capable of.

Read more at Science Daily

Using visual information to learn voluntary behavior while blind

The visual cortex makes up one of the largest regions of the brain, which is a testament to how much information we receive from our eyes. The primary visual cortex, or V1, is the first stage of processing visual input in the brain. Without a functional V1, a person is oblivious to an object that their eyes receive the visual input. However, scientists are in disagreement about whether we must be conscious of what we receive a visual input in order to learn from it. A new study in Scientific Reports by researchers at ASHBi and the University of Sheffield suggests that even if monkeys do not realize they have received a visual signal, they still change their behavior using it.

The loss of the V1 does not mean they do not respond to a visual object, as explained by blindsight, a condition first defined about 50 years ago, in which patients do not consciously detect a visual stimulus but nevertheless localize the target by eye movements or hand reaching. In other words, in blindsight, individuals use visual information of the object but are unaware that they do. Then, to what extent is it possible to act independently of consciousness?

To test this question with regards to blindsight, ASHBi Professor Tadashi Isa, Dr. Rikako Kato and colleagues lesioned V1 in one hemisphere of two monkeys and had them conduct a hidden area search task. In this task, the lesioned monkeys were required to identify the hidden area within a blank screen. When their eyes located the hidden area, a visual signal appeared informing them the area had been discovered, and the monkeys were rewarded with a drop of juice after two seconds delay.

The experiment was designed so that in some cases the visual signal would appear to the intact V1 side and in others it would appear to the lesioned side. The study shows that regardless of the side, the monkeys still identified the hidden area and received the reward. Moreover, the findings suggest that oculomotor behavior after visual cue presentation can be an indicator of confidence. When the confirmation feedback signal was shown to the intact V1 side, the monkeys were certain that they had found the hidden area, as demonstrated by the stopping of searching movements. In contrast, these searching saccadic movements continued when the confirmation signal was shown to the lesioned side.

Dr. Rikako Kato believes deeper study of the brain regions and neural pathways will go beyond understanding the human brain.

Read more at Science Daily