optic nerve Archives - Amazing Health Advances

Researchers Discover Stem Cells in Optic Nerve That Preserve Vision

AHA Publisher — Fri, 31 Jul 2020 07:00:03 +0000

University of Maryland School of Medicine via EurekAlert – Researchers at the University of Maryland School of Medicine (UMSOM) have for the first time identified stem cells in the region of the optic nerve, which transmits signals from the eye to the brain. The finding, published this week in the journal Proceedings of the National Academy of Sciences (PNAS), presents a new theory on why the most common form of glaucoma may develop and provides potential new ways to treat a leading cause of blindness in American adults. “We believe these cells, called neural progenitor cells, are present in the optic nerve tissue at birth and remain for decades, helping to nourish the nerve fibers that form the optic nerve,” said study leader Steven Bernstein, MD, PhD, Professor and Vice Chair of the Department of Ophthalmology and Visual Sciences at the University of Maryland School of Medicine. “Without these cells, the fibers may lose their resistance to stress, and begin to deteriorate, causing damage to the optic nerve, which may ultimately lead to glaucoma.” The study was funded by the National Institutes of Health’s National Eye Institute (NEI), and a number of distinguished researchers served as co-authors on the study. More than 3 million Americans have glaucoma, which results from damage to the optic nerve, causing blindness in 120,000 U.S. patients. This nerve damage is usually related to increased pressure in the eye due to a buildup of fluid that does not drain properly. Blind spots can develop in a patient’s visual field that gradually widen over time. “This is the first time that neural progenitor cells have been discovered in the optic nerve. Without these cells, the nerve is unable to repair itself from damage caused by glaucoma or other conditions. This may lead to permanent vision loss and disability,” said Dr. Bernstein. “The presence of neural stem/progenitor cells opens the door to new treatments to repair damage to the optic nerve, which is very exciting news.” To make the research discovery, Dr. Bernstein and his team examined a narrow band of tissue called the optic nerve lamina. Less than 1 millimeter wide, the lamina lies between the light-sensitive retina tissue at the back of the eye and the optic nerve. The long nerve cell fibers extend from the retina through the lamina, into the optic nerve. What the researchers discovered is that the lamina progenitor cells may be responsible for insulating the fibers immediately after they leave the eye, supporting the connections between nerve cells on the pathway to the brain. The stem cells in the lamina niche bathes these neuron extensions with growth factors, as well as aiding in the formation of the insulating sheath. The researchers were able to confirm the presence of these stem cells by using antibodies and genetically modified animals that identified the specific protein markers on neuronal stem cells. “It took 52 trials to successfully grow the lamina progenitor cells in a culture,” said Dr. Bernstein, “so this was a challenging process.” Dr. Bernstein and his collaborators needed to identify the correct mix of growth factors and other cell culture conditions that would be most conducive for the stem cells to grow and replicate. Eventually the research team found the stem cells could be coaxed into differentiating into several different types of neural cells. These include neurons and glial cells, which are known to be important for cell repair and cell replacement in different brain regions. This discovery may prove to be game-changing for the treatment of eye diseases that affect the optic nerve. Dr. Bernstein and his research team plan to use genetically modified mice to see how the depletion of lamina progenitor cells contributes to diseases such as glaucoma and prevents repair. Future research is needed to explore the neural progenitors repair mechanisms. “If we can identify the critical growth factors that these cells secrete, they may be potentially useful as a cocktail to slow the progression of glaucoma and other age-related vision disorders.” Dr. Bernstein added. The work was supported by NEI grant RO1EY015304, and by a National Institutes of Health shared instrument grant 1S10RR26870-1. “This exciting discovery could usher in a sea change in the field of age-related diseases that cause vision loss,” said E. Albert Reece, MD, PhD, MBA, Executive Vice President for Medical Affairs, UM Baltimore, and the John Z. and Akiko K. Bowers Distinguished Professor and Dean, University of Maryland School of Medicine. “New treatment options are desperately needed for the millions of patients whose vision is severely impacted by glaucoma, and I think this research will provide new hope for them.” To read the original article click here.

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Low-Carbohydrate Diet May Be Associated With Lower Risk of Blinding Eye Disease

AHA Publisher — Fri, 17 Jul 2020 07:00:19 +0000

Mount Sinai Health System via Newswise – Following a long-term diet that’s low in carbohydrates and high in fat and protein from vegetables may lower the risk of the most common subtype of glaucoma. In a first-of-its-kind study, a researcher at New York Eye and Ear Infirmary of Mount Sinai (NYEE) helped discover that if at-risk groups adhere to these dietary restrictions, they may reduce their risk of developing primary open angle glaucoma with early paracentral visual loss by 20 percent. Results from the research have been published in the July 22 issue of Eye-Nature. The study is important because glaucoma is the leading cause of blindness in the United States and primary open angle glaucoma (POAG) is the most common type. POAG is the leading cause of optic nerve degeneration that is related to the pressure level inside the eye, but other factors also contribute to this condition. Patients typically experience few or no symptoms until the disease progresses and they have vision loss. “A diet low in carbohydrates and higher in fats and proteins results in the generation of metabolites favorable for the mitochondrion-rich optic nerve head, which is the site of damage in POAG. This dietary pattern has already been shown to have favorable results for epilepsy and showed some promising results for Parkinson’s and Alzheimer’s diseases,” said co-corresponding author Louis R. Pasquale, MD, FARVO, Deputy Chair for Ophthalmology Research for the Mount Sinai Health System. “It’s important to note that a low-carbohydrate diet won’t stop glaucoma progression if you already have it, but it may be a means to preventing glaucoma in high-risk groups. If more patients in these high-risk categories—including those with a family history of glaucoma—adhered to this diet, there might be fewer cases of vision loss.” Past studies have shown that a ketogenic diet (low-carbohydrate and high-fat) has a protective effect against neurologic disorders. Ketone bodies (energy compounds produced as the body metabolizes fats) are substituted for glucose as a major energy source for the brain and using more of these under a ketogenic diet may improve function and slow down neuronal degeneration. However, more recent studies have shown that a low-carbohydrate diet that does not restrict protein or total calories may have similar neuroprotective properties; this diet has been recognized as a more practical alternative to a ketogenic diet, as it’s easier to follow and does not have the adverse effects of the ketogenic diet (which range from headache, weakness, and irritability to constipation, nausea, and vomiting). A team of researchers wanted to know if a low-carbohydrate diet could positively impact the optic nerve. The optic nerve sits in the back of the eye and transfers visual information from the retina to the brain through electrical impulses. The optic nerve has a large concentration of mitochondria (mitochondria represent the major source of a cell’s energy supply and lead to a cell’s survival), and has high-energy requirements. Since glaucoma is a condition that may be associated with mitochondrial dysfunction, researchers wanted to find out if substituting protein and fat for carbohydrates in the diet would enhance mitochondrial activity, maintain optic nerve function, and prevent optic nerve degeneration in this blinding eye disease. They performed a large-scale meta-analysis to get this answer. They followed 185,000 adult participants from three large studies in the United States, conducted between 1976 and 2017. Participants were female nurses and male health professionals between the ages of 40 and 75. Every two to four years, they filled out food frequency questionnaires that assessed what they ate and drank. They also answered questions about their health and what diseases, if any, they might be developing. If they said they had glaucoma, the researchers asked their treating eye care providers to send medical records to determine if they had POAG. The research team created statistical models based on the patients’ questionnaire responses, dividing them into groups based on carbohydrate intake, so they could look across the spectrum from high to low carbohydrate intake and see any possible relationship with POAG. They specifically looked at three different ways of achieving a low-carbohydrate diet: substituting animal-based fats and proteins for carbohydrates; substituting plant-based based fats and proteins for carbohydrates; and replacing carbohydrates with high fats and proteins regardless of the source. Researchers then calculated the relative risk of POAG after adjusting for multiple factors for each of the dietary patterns including age, race, and body mass index. Patients in the low-carbohydrate intake group who followed a diet of increased plant-based fat and protein were associated with a 20 percent lower risk of developing POAG subtype with paracentral visual field loss compared to those in the high-carbohydrate intake group. However, the researchers did not find any association between POAG and a low-carbohydrate diet without accounting for the source protein or fat, and they did not find any association between glaucoma and an animal-based low-carbohydrate diet. Their findings suggest vegetable sources may be more beneficial than animal sources for a low-carbohydrate diet with respect to reducing risk of the specific glaucoma subtype with early paracentral visual loss. “This was an observational study and not a clinical trial, so more work is needed as this is the first study looking at this dietary pattern in relation to POAG. The next step is to use artificial intelligence to objectively quantify paracentral visual loss in our glaucoma cases and repeat the analysis,” adds Dr. Pasquale. “It’s also important to identify patients who have a genetic makeup of primary open angle glaucoma who may benefit from a low-carbohydrate diet. This dietary pattern may be protective only in people with a certain genetic makeup.” To read the original article click here.

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