Researchers identify candidate biomarker of accelerated onset diabetic retinopathy

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Posted on 4th April 2016 by Pacific ClearVision Institute in General |Retina

Researchers from Massachusetts Eye and Ear and Schepens Eye Research Institute have shown an association between a defective myogenic response — the regulatory increase or decrease in blood pressure to keep blood flow within the vessels of the retina constant — and early, accelerated development of retinopathy in patients with type 1 diabetes. These findings, published online today in Investigative Ophthalmology and Visual Science, identify one mechanism to explain why some patients develop diabetic retinopathy sooner than others. Furthermore, the findings provide a target for future study, which may lead to therapies to delay or prevent the development of accelerated onset diabetic retinopathy.

“In patients with a normal myogenic response, the retinal vessels constrict when increased pressure arrives, to maintain constant blood flow and avoid damage to the smaller vessels in the retina,” said Mara Lorenzi, M.D., senior scientist at Massachusetts Eye and Ear/Schepens Eye Research Institute and a professor of ophthalmology, part-time at Harvard Medical School. “But we saw that, in about half of the diabetic patients in our study, the vessels did not constrict. In fact, paradoxically, some patients’ vessels dilated, and the blood flow to the retina was increased. This becomes a mechanism of damage for the small vessels, because these tiny, delicate capillaries are exposed to a big flow of pressure that can lead to the little hemorrhages and fluid leakage that are characteristic of diabetic retinopathy.”

The study included a small prospective study, in which the researchers closely followed 17 patients with type 1 diabetes whose myogenic responses had been measured four years prior. In approximately half of those patients, the researchers had observed defective myogenic responses. Five out of seven patients with defective myogenic responses developed accelerated diabetic retinopathy. The study also included a different group of patients with type 1 diabetes who had just developed retinopathy. Among these patients, the defective myogenic response was found only in those in whom retinopathy had appeared after a short duration of diabetes (fewer than 15 years of diabetes).

The most common diabetic eye disease and a leading cause of blindness in American adults, diabetic retinopathy occurs when blood vessels in the retina become damaged and leak fluid. Accumulation of fluid into the retina can lead to macular edema . As the damage due to diabetes progresses, the vessels become occluded and can no longer carry blood. New blood vessels grow on the surface of the retina (proliferative retinopathy); but the new vessels are immature and may rupture impairing vision.. Loss of visual acuity as a result of diabetic retinopathy is often the first warning sign for patients yet to be diagnosed with type 2 diabetes.

Currently, there are no treatments for diabetic retinopathy beyond controlling blood sugar and blood pressure levels. The new vessels of proliferative retinopathy can be treated with laser techniques, often at the expense of a portion of the retina. With the knowledge gained from the new studies, the researchers hope to target the defective myogenic response and develop therapies to prevent the development of accelerated diabetic retinopathy in this population. A larger study is needed to test the predictive capability of this abnormality.

“Now, we have a target to be investigated for the development of drugs or interventions to halt or stall the onset of clinical retinopathy,” Dr. Lorenzi said.

The invisible world of human perception

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Posted on 4th April 2016 by Pacific ClearVision Institute in General |Retina

Stage magicians are not the only ones who can distract the eye: a new cognitive psychology experiment demonstrates how all human beings have a built-in ability to stop paying attention to objects that are right in front of them.

Perception experts have long known that we see much less of the world than we think we do. A person creates a mental model of their surroundings by stitching together scraps of visual information gleaned while shifting attention from place to place. Counterintuitively, the very process that creates the illusion of a complete picture relies on filtering out most of what’s out there.

In a paper published in the journal Attention, Perception, & Psychophysics a team of U of T researchers reveal how people have more “top-down” control of what they don’t notice than many scientists previously believed.

“The visual system really cares about objects,” says postdoctoral fellow J. Eric T. Taylor, who is the lead author on the paper. “If I move around a room, the locations of all the objects — chairs, tables, doors, walls, etc. — change on my retina, but my mental representation of the room stays the same.”

Objects play such a fundamental role in how we focus our attention that many perception researchers believe we are “addicted” to them; we couldn’t stop paying attention to objects if we tried. The visual brain guides attention largely by selecting objects — and this process is widely believed to be automatic.

“I had an inkling that object-based attention cues require a little more will on the observer’s part,” says Taylor. “I designed an experiment to determine whether you can ‘erase’ object-based attention shifting.”

Taylor put a new twist on an old and highly influential test known as a “two-rectangle experiment.” The original experiment was instrumental in demonstrating just how deeply objects are ingrained in how we see the world.

In the original experiment, test subjects stare at a screen with two skinny rectangles. A brief flash of light draws their attention to one end of one rectangle — say the top end of the left rectangle. Then, a “target” appears, either in the same place as the flash, at the other end of the same rectangle, or at one of the ends of the other rectangle.

Observers are consistently faster at seeing the target if it appeared at the opposite end of the original rectangle than if it appeared at the top of the other rectangle — even though those two points are precisely the same distance from the original flash of light.

The widely accepted conclusion was that the human brain is wired to use objects like these rectangles to focus attention. Alternately referred to as a “bottom-up” control or a “part of our lizard brain,” object-based attention cues seemed to evoke an involuntary, uncontrolled response in the human brain.

Taylor and colleague’s variations added a new element: test observers went through similar exercises, but they were instructed to hunt targets of a specific colour that either matched or contrasted with the color of the rectangles themselves.

“They activate a ‘control setting’ for, say, green, which is a very top-down mental activity,” says Taylor. “We found that when the objects matched the target color, people use them to help direct their attention. But when the objects were not the target color, people no longer use them — they become invisible.”

Test observers are aware of the rectangles on the screen, but when they’re seeking a green target among red shapes, those objects no longer affect the speed with which they find it. In everyday life, we continually create such top-down filters, by doing anything from heeding a “Watch for children” sign to scanning a crowd for a familiar face.

“This result tells us that one of the ways we move attention around is actually highly directed rather than automatic,” Taylor says. “We can’t say exactly what we’re missing, but whatever is and is not getting through the filter is not as automatic as we thought.”

Stem cells used to identify cellular processes related to glaucoma

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Posted on 4th April 2016 by Pacific ClearVision Institute in General |Retina

Using stem cells derived from human skin cells, researchers led by Jason Meyer, assistant professor of biology, along with graduate student Sarah Ohlemacher of the School of Science at Indiana University-Purdue University Indianapolis, have successfully demonstrated the ability to turn stem cells into retinal ganglion cells (RGCs), the neurons that conduct visual information from the eye to the brain. Their goal is the development of therapies to prevent or cure glaucoma.

In addition to glaucoma, a group of degenerative diseases that damage the eye’s optic nerve and can result in vision loss and blindness, this work has potential implications for treatment of optic- nerve injuries of the types incurred by soldiers in combat or athletes in contact sports.

In the study, which appears online in advance of publication in the journal Stem Cells, the IUPUI investigators took skin cells biopsied from volunteers with an inherited form of glaucoma and from volunteers without the disease and genetically reprogrammed them to become pluripotent stem cells, meaning they are able to differentiate into any cell type in the body. The researchers then directed the stem cells to become RGCs at which point the cells began adopting features specific to RGCs — features that were different in the cells of individuals with glaucoma than in the cells that came from healthy individuals.

Glaucoma is the most common disease that affects RGCs, which serve as the connection between the eye and the brain, sending information taken in by the eye to the brain for interpretation. When these cells are damaged or severed, the brain cannot receive critical information, leading to blindness. The National Institutes of Health’s National Eye Institute estimates that glaucoma affects more than 2.7 million people in the United States and more than 60 million worldwide.

“Skin cells from individuals with glaucoma are no different from skin cells of those without glaucoma,” said Meyer, a cell biologist and stem cell researcher, who also holds an appointment as a primary investigator with the Stark Neurosciences Research Institute at the Indiana University School of Medicine. “However, when we turned glaucoma patients’ skin cells into stem cells and then into RGCs, the cells became unhealthy and started dying off at a much faster rate than those of healthy individuals.

“Now that we have produced cells that develop features of glaucoma in culture dishes, we want to see if compounds we add to these RGCs can slow down the degeneration process or prevent these cells from dying off. We already have found candidates that look promising and are studying them. In the more distant future, we may be able to use healthy patient cells as substitute cells as we learn how to replace cells lost to the disease. It’s a significant challenge, but it’s the ultimate — and, we think, not unrealistic — long-range goal.”

New treatment for common incurable eye condition: Pterygium/pinguecula treatment results

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Posted on 4th April 2016 by Pacific ClearVision Institute in General |Retina

At the Israeli Society for Vision and Eye Research (ISVER) conference on March 10, the MedInsight Research Institute and Center for Drug Repurposing at Ariel University presented the latest findings on positive user-reported outcomes of the repurposed drug dipyridamole in treating pterygium and related dry-eye symptoms.

Dipyridamole is a cardiovascular drug, used for the past 55 years for treating angina and preventing stroke. It also has wide applicability for eye disorders, having been researched for various eye ailments over the past four decades, including diabetic retinopathy, ocular hypertension and retinal hemorrhage. In 2014, MedInsight published the first case report of a pterygium patient being successfully treated with dipyridamole eye drops.

Pterygium, or Surfer’s Eye, is a benign growth that affects 10% of the population worldwide. It is more prevalent with older age. An early-stage pterygium is known as a pinguecula, and affects 50% of the population. Besides being unsightly, pterygium and pinguecula often become inflamed and cause dry eye. Eventually, they can completely obstruct vision.

In the findings presented at ISVER in Kfar Maccabia, Israel, researchers analyzed outcomes of dry-eye symptoms reported by patients with pterygium. Using a well-accepted survey known as the Ocular Surface Disease Index, OSDI, the researchers found that there was a maximum reduction in OSDI scores averaging 52.4% during the course of treatment for 25 patients. Some patients reported a complete resolution of symptoms. Photographic evidence showed marked antiangiogenic effects and regression of the pterygia.

“These results are very exciting,” said Moshe Rogosnitzky, director of the Center for Drug Repurposing at Ariel University, who discovered this novel treatment. “Until now, the only known treatment for pterygium has been surgical removal, which involves a high recurrence rate. In addition, patients are often given topical steroids to treat their symptoms, but this can result in glaucoma. Now we have a promising potential treatment for this very difficult to treat disorder, and it appears to be not only effective, but entails only a small amount of a very safe medicine. This treatment possibility offers very distinct advantages over the existing treatment offered.”

Aaron Frenkel, research coordinator for MedInsight, added that studies are currently being planned at medical centers in Israel, Europe, Turkey and India. “This drug does not yet have commercial sponsorship, so studies are taking longer to initiate since research funds are dependent on donors. We are hopeful that clinical trials will begin later this year,” said Frenkel.

April is Sports Eye Injury Awareness Month

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Posted on 4th April 2016 by Pacific ClearVision Institute in General |Retina

Parents and coaches play an important role in making sure young athletes protect their eyes and properly gear up for the game. Protective eyewear should be part of any uniform because it plays such an important role in reducing sports-related eye injury.

Eye injuries are the leading cause of blindness in children in the United States and most injuries occurring in school-aged children are sports-related. These injuries account for an estimated 100,000 physician visits per year at a cost of more than $175 million.

Ninety percent of sports-related eye injuries can be avoided with the use of protective eyewear. Protective eyewear includes safety glasses and goggles, safety shields, and eye guards designed for a particular sport. Ordinary prescription glasses, contact lenses, and sunglasses do not protect against eye injuries. Safety goggles should be worn over them.

Currently, most youth sports leagues do not require the use of eye protection. Parents and coaches must insist that children wear safety glasses or goggles whenever they play.

Protective eyewear, which is made of ultra-strong polycarbonate, is 10 times more impact resistant than other plastics, and does not reduce vision. All children who play sports should use protective eyewear-not just those who wear eyeglasses or contact lenses. For children who do wear glasses or contact lenses, most protective eyewear can be made to match their prescriptions. It is especially important for student athletes who have vision in only one eye or a history of eye injury or eye surgery to use protective eyewear.

Whether you are a parent, teacher, or coach, you can encourage schools to adopt a policy on protective eyewear. Meanwhile, parents and coaches should insist that children wear protective eyewear whenever they play sports and be good role models and wear it themselves.

Courtesy of: National Eye Institute

Take the following steps to avoid sports eye injuries:

- Wear proper safety goggles (lensed polycarbonate protectors) for racquet sports or basketball. In order to be assured that your eyes are protected, it is important that any eye guard or sports protective eyewear are labeled as ASTM F803 approved. This eyewear is performance tested to give you the highest levels of protection.

- Use batting helmets with polycarbonate face shields for youth baseball.

- Use helmets and face shields approved by the U.S. Amateur Hockey Association when playing hockey.

- Know that regular glasses don’t provide enough protection.