Posts tagged vision loss
Articles and news from the latest research reports.
Easier test for blindness cause
Scientists from Australia’s Vision Centre have demonstrated a quick, accurate test under lights for one of the world’s leading causes of blindness.
A new study shows that age-related macular degeneration (AMD) can be just as effectively and more rapidly and inexpensively diagnosed under bright lights, instead of requiring patients to sit for 20 minutes in a darkened room.
“AMD accounts for half of the legal blindness cases in Australia,” says Professor Ted Maddess from The Vision Centre and The Australian National University. “It affects one in seven people over the age of 50, costing the nation $2.6 billion a year. Globally, it affects 25 to 30 million people, with an annual cost of $343 billion.
“While current tests for AMD are done in the light, scientists have proposed that it might be better if the patient has their vision adapted to the dark prior to the test,” he says.
“This is because they had found that rod receptors – vision cells that we use to see in black and white and in low light – die earlier in AMD than the cone receptors we use to see in colour during the day. So it had been suggested that AMD tests would be more accurate if they were based on the health of a person’s rods.”
Surgeons at UC Davis Medical Center have successfully implanted a new telescope implant in the eye of a patient with end-stage age-related macular degeneration (AMD), the most advanced form of the disease and a leading cause of blindness in older Americans.
The device, approved by the Food and Drug Administration in 2010, is the only medical/surgical option available that restores a portion of vision lost to the disease. UC Davis Health System’s Eye Center, in collaboration with the Society for the Blind, is one of the few in California and the nation to offer the innovative procedure.
Researchers identify mechanism that leads to diabetes, blindness
The rare disorder Wolfram syndrome is caused by mutations in a single gene, but its effects on the body are far reaching. The disease leads to diabetes, hearing and vision loss, nerve cell damage that causes motor difficulties, and early death.
Now, researchers at Washington University School of Medicine in St. Louis, the Joslin Diabetes Center in Boston and the Novartis Institutes for BioMedical Research report that they have identified a mechanism related to mutations in the WFS1 gene that affects insulin-secreting beta cells. The finding will aid in the understanding of Wolfram syndrome and also may be important in the treatment of milder forms of diabetes and other disorders.
The study is published online in the journal Nature Cell Biology
“We found something we didn’t expect,” says researcher Fumihiko Urano, MD, PhD, associate professor of medicine in Washington University’s Division of Endocrinology, Metabolism and Lipid Research. “The study showed that the WFS1 gene is crucial to producing a key molecule involved in controlling the metabolic activities of individual cells.” That molecule is called cyclic AMP (cyclic adenosine monophosphate).
Insulin-secreting beta cells in the pancreas (above) cannot make enough cyclic AMP in patients with Wolfram syndrome. As a result, the pancreas produces and secretes less insulin, and the cells eventually die.
In insulin-secreting beta cells in the pancreas, for example, cyclic AMP rises in response to high blood sugar, causing those cells to produce and secrete insulin.
“I would compare cyclic AMP to money,” Urano says. “You can’t just take something you make to the store and use it to buy food. First, you have to convert it into money. Then, you use the money to buy food. In the body, external signals stimulate a cell to make cyclic AMP, and then the cyclic AMP, like money, can ‘buy’ insulin or whatever else may be needed.”
The reason patients with Wolfram syndrome experience so many problems, he says, is because mutations in the WFS1 gene interfere with cyclic AMP production in beta cells in the pancreas.
“In patients with Wolfram syndrome, there is no available WFS1 protein, and that protein is key in cyclic AMP production,” he explains. “Then, because levels of cyclic AMP are low in insulin-secreting beta cells, those cells produce and secrete less insulin. And in nerve cells, less cyclic AMP can lead to nerve cell dysfunction and death.”
By finding that cyclic AMP production is affected by mutations in the WFS1 gene, researchers now have a potential target for understanding and treating Wolfram syndrome.
“I don’t know whether we can find a way to control cyclic AMP production in specific tissues,” he says. “But if that’s possible, it could help a great deal.”
Meanwhile, although Wolfram syndrome is rare, affecting about 1 in 500,000 people, Urano says the findings also may be important to more common disorders.
“It’s likely this mechanism is related to diseases such as type 2 diabetes,” he says. “If a complete absence of the WFS1 protein causes Wolfram syndrome, perhaps a partial impairment leads to something milder, like diabetes.”
(Source: news.wustl.edu)
Implantable Telescope Technology
Implantable Miniature Telescope along with the cornea, enlarges images in front of the eye approximately 2.2 or 2.7 times their normal size (depending on the model used). The magnification allows central images to be projected onto healthy perimacular areas of the retina instead of the macula alone, where breakdown of photoreceptors and loss of vision has occurred. This helps reduce the ‘blind spot’ and allows the patient to distinguish and discern images that may have been unrecognizable or difficult to see.
The telescope is about the size of a pea (3.6 mm diameter; 4.4 mm length) and is surgically placed inside the eye.