Shining light on diabetes-related blindnessMarch 12, 2009A group of scientists in California is trying to develop a cheaper, less invasive way to spot the early stages of retinal damage from diabetic retinopathy, the leading cause of blindness in American adults, before it leads to blindness. As described in the special Interactive Science Publishing (ISP) issue of Optics Express, the Optical Society's (OSA) open-access journal, the scientists are using beams of light to measure blood flow in the back of the eye. "The more severe the retinopathy, the lower the blood flow to the retina," says David Huang of the Keck School of Medicine at the University of Southern California in Los Angeles. This observation may lead to better ways to diagnose the condition early. Diabetic retinopathy is caused by damage to blood vessels in the eye's retina. According to the U.S. Centers for Disease Control and Prevention, 5.5 million people over the age of 40 suffered from this condition in 2005, and this number is expected to triple by 2050 as the number of people with diabetes continues to increase. But there's hope; vision loss is preventable if retinal damage is detected early enough. Affecting everyone who has type 1 diabetes and most people with type 2, diabetic retinopathy progresses in two stages. It begins when the small vessels that carry blood to and from the eye swell and leak, which can lead to slow vision loss as the health of the retina degenerates. In 20 percent of patients, the disease then progresses to advanced "proliferative" retinopathy. The oxygen-starved retina calls out to the circulatory system for help, which responds by forming new, abnormal blood vessels. These fragile vessels have thin walls that tend to scar and hemorrhage, causing sudden vision loss. Huang and colleagues have adapted a spectroscopic technology called optical coherence tomography (OCT) -- normally used take cross-sectional pictures of the retina -- to directly detect the amount of blood flowing through retinal blood vessels. A diode on the OCT instrument beams infrared light into the blood vessel of interest. The frequency of light that bounces back is shifted slightly by the fast-moving blood, a Doppler effect similar to the pitch shift in the sound of a train as it rushes by. Using this technique, the team estimated the total amount of blood flow in the retinal veins of two people with diabetes, to within 10 percent. They detected less blood flowing in the person who had advanced proliferative retinopathy. Further unpublished results in six more patients support this finding, but the next step, according to Huang, will be a larger clinical trial to verify this observation with statistical significance. The most common method currently used by ophthalmologists to detect retinopathy is a fluorescein angiography, an injection of dye into retinal veins used to spot leaks. This moderately invasive technique can cause nausea and vomiting and, in rare cases, severe allergic reactions. OCT may provide a more quantitative, less invasive way to diagnose the condition, says Huang. It may also cut costs by circumventing the expensive equipment required for flourescein angiography. "It just requires special scanning software that could easily be put on the OCT machines that most retinal specialists have," he says. He hopes that this combination of factors will give ophthalmologists an easy way to check for problems early and often. Detecting leaky blood vessels early helps patients choose between different treatment options. "People with poor blood flow don't respond well to some of the laser treatments used for retinopathy, and they are at a higher risk for proliferative retinopathy," says Huang. Huang's research takes advantage of ISP, an initiative undertaken by OSA in partnership with the National Library of Medicine, part of the National Institutes of Health, and with the support of the United States Air Force Office of Scientific Research. This initiative allows scientists to expand upon traditional research results by providing software for interactively viewing underlying source data and to objectively compare the performance of different technologies. This data may be related to medical images, such as those taken with X-rays, MRIs, CT scans and ultrasounds, or it may be created in research involving oil and gas exploration, climatology, pollution monitoring and many other fields. Specifically in this instance, researchers are able to look at the actual OCT scans from the study patients as they read the paper. The software was developed in conjunction with Kitware, Inc. For more information on ISP, visit http://www.opticsinfobase.org/isp.cfm. Optical Society of America |
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| Related Retinopathy Current Events and Retinopathy News Articles Cataract surgery helps AMD patients; steroid improves DME; online eye health forum This month's Ophthalmology, the journal of the American Academy of Ophthalmology (Academy) reports on a national study that finds cataract surgery is likely to benefit patients with age-related macular degeneration (AMD) at all stages of the disease, on a clinical trial showing that the steroid triamcinolone may be effective in advanced diabetic macular edema (DME) patients when standard treatment fails, and on the public's use of two Academy-sponsored online eye health forums. Clues to visual variant Alzheimer's; myopia and diabetic retinopathy risk Two studies are of particular note in today's Scientific Program of the 2009 Joint Meeting of the American Academy of Ophthalmology (AAO) and the Pan-American Association of Ophthalmology (PAAO): a report by Swiss neuro-ophthalmic researchers about vision exam clues that should make ophthalmologists suspect an atypical variant of Alzheimer's disease; and new evidence from a Singapore National Eye Center study that diabetics who are nearsighted may be less susceptible to diabetic retinopathy. Treating ROP in tiny preemies; better glaucoma follow-up in urban clinic Highlights of today's Scientific Program of the 2009 American Academy of Ophthalmology (AAO) - Pan-American Association of Ophthalmology (PAAO) Joint Meeting include: John T. Flynn, MD, Columbia University School of Medicine, discussing the ever-tougher challenges Eye M.D.s face in caring for the vision of the tiniest premature babies; and a report by Bradford W. Lee, MD, Stanford University School of Medicine, on barriers to glaucoma follow-up as perceived by patients in an urban, culturally diverse clinic. First in New York: Bionic technology aims to give sight to woman blinded beginning at age 13 A 50-year-old New York woman who was diagnosed with a progressive blinding disease at age 13 was implanted with an experimental electronic eye implant that has partially restored her vision. More infants surviving pre-term births results in higher rates of eye problems As more extremely pre-term infants survive in Sweden, an increasing number of babies are experiencing vision problems caused by abnormalities involving the retina. New device finds early signs of eye disease in preemies Tell-tale signs of a condition that can blind premature babies are being seen for the first time using a new handheld device in a study at Duke University Medical Center. Rare genetic disease successfully reversed using stem cell transplantation A recent study by Scripps Research Institute scientists offers good news for families of children afflicted with the rare genetic disorder, cystinosis. Elevated arginase levels contribute to vascular eye disease such as diabetic retinopathy Elevated levels of the enzyme arginase contribute to vascular eye damage and Medical College of Georgia researchers say therapies to normalize its levels could halt progression of potentially blinding diseases such as diabetic retinopathy. Anti-growth factor drugs raise hope and concern for treatment of children's eye diseases A new class of antibody drugs may provide a powerful new tool for the treatment of eye diseases in children, but specialists need to be alert for the possibility of serious side effects, according to an editorial in the August Journal of AAPOS (American Association for Pediatric Ophthalmology and Strabismus), published by Elsevier. Natural Compound Stops Diabetic Retinopathy Researchers at the University of Oklahoma Health Sciences Center have found a way to use a natural compound to stop one of the leading causes of blindness in the United States. More Retinopathy Current Events and Retinopathy News Articles |
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