Dr. Grossman’s Blog

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Early diagnosis is key to dealing effectively with eye diseases, especially diabetic retinopathy, macular degeneration, and glaucoma.

Researchers from around the country are working together to adapt the technologies that allow astronomers to observe distant galleries so that eye doctors can better examine the retina even through imperfections on the lens and cornea.  These adaptive optics–optical coherence tomography (AO-OCT) systems could be the wave of the future for eye disease diagnosis.

Read more about this technology at Scientific American.

Learn more about how to prevent eye disease at our website.

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Recent research has shown that glaucoma may not originate in the retina itself, but at the other end of the optic nerve located back in the middle of the brain.  In a study of rodents published in PNAS, it was found that the problem may stem from the nerve’s inability to transport impulses.  The scientists from Vanderbilt University and University of Washington say that this transport deficit seems related to the subject’s age and is not necessarily related in increased ocular pressure.  Locating glaucoma’s cause in the nerve rather than the retina may lead to new breakthroughs in glaucoma detection and therapy.

Source: http://www.pnas.org/content/107/11/5196.abstract

Learn more about who is at risk for glaucoma and how to prevent the eye disease known as “the silent thief.”

Australian scientists may have made a discovery that could lead to the development of better tests to detect eye diseases like glaucoma and macular degeneration.  Research published in  the Journal of Vision suggests that color sensing cells in retina, which were previously believed to be able to only respond to specific colors, can also detect black and white moving objects as well.  According to lead researcher Paul Martin: “For a long time we’ve had an image of the brain as a kind of computer, with particular pathways or ‘wires’ for particular nerve signals.  Now, it is becoming clear the wiring is a lot less precise than a computer.”

What might this mean for you when its time to be screened for eye disease?  Discoveries like this one help scientists better understand how cells in the eyes respond to stimuli, and the more they know about how the eye works, the more able they are to improve eye testing procedures and technologies.

Source: ABC Science

Scientists at UC Irvine have created an early stage retina from human embryonic stem cells.  It is the first three-dimensional tissue structure to be made from stem cells and bring us closer to the development of transplant-ready retinas to treat eye disorders such as retinitis pigmentosa and macular degeneration that affect millions.  Researchers managed to employ a technique that allowed them to create the multiple cell types necessary for the retina.

Source: Journal of Neuroscience Methods, 4-24-10.

Homocysteine, an amino acid believed to contribute to heart attack, stroke and dementia, may also play a role in retinal damage and vision loss.  Homocysteine levels rise when folic acid levels drop, a common problem for Americans whose diets are often poor in folate-rich fruits, tomatoes, vegetables and grains.

Dr. Sylvia Smith, cell biologist at Medical College of Georgia (MCG), and Dr. Vadivel Ganapathy, chair of the MCG Department of Biochemistry and Molecular Biology are studying the consequence of slightly elevated homocysteine on the retina under a $1.8 million grant from the National Institutes of Health.  They want to learn the impact of elevated homocysteine levels on the extensive blood vessel and neuronal network of the retina; their preliminary evidence suggests that it isn’t good.

“You don’t have to be a cell biologist to see that there is a problem in this retina. It’s terribly disrupted,” Dr. Smith says, looking at images of a fragmented 10-layer retina exposed to high levels of homocysteine.  A healthy retina is “beautifully” organized, horizontally and vertically, she says.

Folate and vitamin B12 convert homocysteine to methionine, an amino acid essential to protein synthesis.  Dr. Ganapathy notes that people need only about 1 microgram per day of vitamin B12, which comes from microorganisms common in animals’ gastrointestinal tract. Strict vegetarians are typically the only Americans who have problems with B12 deficiency, he says. People need about 400 micrograms of folate daily. Pregnant women as well as those trying to become pregnant need at least double that.

Researchers are studying a mouse model with a slightly elevated homocysteine level that simulates a low-folate diet in humans; a version of the mouse that also has diabetes, which goes along with cardiovascular disease and retinopathy; and a second model of the rare genetic defect that results in extraordinarily high homocysteine levels.  These mice will be put on diets that elevate and lower folate levels, so that resultant homocysteine levels and the impact on the retina can be studied.

Researchers hypothesize that sustained elevation will compromise retinal function and degrade the once well-stratified tissue; in pilot studies, the researchers have shown that diabetes exacerbates this problem.

SOURCE:  Medical College of Georgia, “Impact of elevated homocysteine levels on vision under study,” Oct. 15, 2007.