Vision, Dyslexia Not Linked: Study

Findings will advance understanding, treatment of the reading disorder, says expert

By Dennis Thompson

HealthDay Reporter

THURSDAY, June 6 (HealthDay News) -- A new brain imaging study appears to rule out one potential cause of dyslexia, finding that vision problems don't lead to the common reading disorder.

The new research could have a wide-ranging impact on the detection and treatment of dyslexia, said senior study author Guinevere Eden, director of the Center for the Study of Learning at Georgetown University Medical Center. The study appears June 6 in the journal Neuron.

"It has importance from a practical viewpoint. It means you shouldn't focus on the visual system as a way to diagnose dyslexia or treat dyslexia," Eden said. "Until now, there was still this uncertainty where some people were saying, 'I know it's controversial but I still believe that vision is contributing to these kids' reading problem.' We now have a finding that really speaks to an understanding that visual system function shouldn't have a role in diagnosis or treatment."

People with dyslexia struggle to learn to read fluently and accurately. Dyslexia may affect more than one of every 10 people in the United States, and it is the nation's most common learning disability, according to background information in the study.

Earlier brain imaging studies have found that people with dyslexia experience subtle weaknesses in processing visual stimuli compared with people their same age, leading some to wonder whether this visual dysfunction causes dyslexia by interfering with a child's ability to read.

But the study found that visual problems noted in people with dyslexia likely are a result of the learning disorder rather than the cause, Eden said.

By ruling out the visual center as a culprit, the new study provides more support to the already popular theory that dyslexia occurs because of weaknesses in the part of the brain that deals with language, she said.

Researchers used functional MRIs to compare the brains of dyslexic children with the brains of children who don't have the learning disorder.

Children without dyslexia appeared to have the same level of visual processing activity as dyslexic kids, when matched by reading level instead of age, they found.

Further, children with dyslexia who received intensive tutoring in reading skills experienced a subsequent increase in visual system activity.

"When we ask children to learn to read, we are asking them to do something that is very difficult. Learning to read changes the brain," Eden said. "If you are a struggling reader because of your dyslexia, you don't have as much opportunity to read as the other kid in your class, and so your brain doesn't get the chance to change as much. The visual deficit is there, but our study allowed us to conclude it's there as a consequence of not having the same opportunity to read as children without dyslexia."

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Vision Loss, Depression May Be Linked, Study Finds

Title: Vision Loss, Depression May Be Linked, Study Finds
Category: Health News
Created: 3/7/2013 4:36:00 PM
Last Editorial Review: 3/8/2013 12:00:00 AM

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FDA Approves 'Bionic Eye' to Help Against Rare Vision Disorder

Title: FDA Approves 'Bionic Eye' to Help Against Rare Vision Disorder
Category: Health News
Created: 2/14/2013 6:36:00 PM
Last Editorial Review: 2/15/2013 12:00:00 AM

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FDA Approves 'Bionic Eye' to Help Against Rare Vision Disorder

By Steven Reinberg

HealthDay Reporter

THURSDAY, Feb. 14 (HealthDay News) -- An implanted, sight-enhancing device some are calling a "bionic eye" is the first to gain approval for use in the United States, officials announced Thursday.

According to the U.S. Food and Drug Administration, the new Argus II Retinal Prosthesis System can help patients with a genetic eye disease called retinitis pigmentosa regain some sense of vision. About 100,000 Americans are believed to be affected by the illness, which causes a gradual deterioration of the eyes' photoreceptor cells.

The new device uses a tiny video camera attached to eyeglasses that transmits images to a sheet of electrode sensors that have been sewn into the patient's eye. These sensors then transmit those signals to the brain via the optic nerve. The device helps replace the damaged cells of the retina and helps patients see images or detect movement.

"It's a start, it's a beginning," said Dr. Mark Fromer, an ophthalmologist at Lenox Hill Hospital in New York City. "It's going to be exciting for people who get this device who are currently just seeing light or dark, [they] will see shapes and that will be life-altering for them."

An FDA official was similarly enthused.

"For many of the approximately 1,300 individuals who will develop the disease this year, this technology may change their lives," Dr. William Maisel, deputy director for science and chief scientist at FDA's Center for Devices and Radiological Health, said in an agency blog post. "It's the difference between night and day," he added.

Maisel's post also included testimony from people who had tested the device and spoke in favor of its approval at a recent FDA hearing:

"The biggest thing to me was being able to see the crosswalk lines on the street so I can safely cross streets in Manhattan," one user said.

"The most exciting day to me was October 27th, in 2009," another testified. "It was the first time I was able to see letters on the monitor screen [during a test of visual perception]. I had not seen letters since 1994, so that was huge."

A third person said he had a 17-year-old son, "and I don't mind telling you how much -- I mean, how happy that made me, not only to see the silhouette of my son, but to hear that voice coming and saying, 'Yeah, it's me, Dad. I'm here and I love you.'"

People with retinitis pigmentosa suffer damage to the light-sensitive cells of the retina. As these cells slowly degenerate, patients lose side vision and night vision and later on, central vision. The disease can cause blindness,

The FDA's approval is a limited one, labeled a "humanitarian use device" approval, meaning the Argus II can be used only for fewer than 4,000 patients per year.

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Vision Problems Rising Rapidly in the U.S.

Dec. 11, 2012 -- The diabetes and obesity epidemics may be fueling a dramatic rise in the number of people with vision problems, a new study suggests.

Rates of vision problems that can’t be treated with glasses or contact lenses, known as nonrefractive vision problems, increased by 21% between two survey periods: 1999 to 2002 and 2005 to 2008. The findings suggest that as many as 700,000 more people developed these types of vision problems in a short amount of time.

Nonrefractive vision problems include glaucoma, macular degeneration, cataracts, and diabetes-related eye disease. They are caused by underlying diseases. Many of these diseases are age-related and would not be expected to increase among young people. Diabetes, however, is occurring in younger and younger people.

“The increasing diabetes prevalence in the U.S. is leading to more vision loss,” says researcher David S. Friedman, MD, PhD, MPH. He is the director of the Dana Center for Preventive Ophthalmology at the Johns Hopkins Wilmer Eye Institute and Bloomberg School of Public Health in Baltimore. “We have to recognize that this is a large public health problem so we can start developing methods to deal with it.”

The findings appear in the Dec. 12 issue of the Journal of American Medical Association.

Friedman and colleagues analyzed data from a large national database in 1999-2002 and 2005-2008. Participants aged 20 or older answered questions and underwent lab tests and physical exams.  

Those most at risk were older, poorer, had less education, and had diabetes for 10 or more years. The only one of these risks that increased between the two surveys was a history of diabetes.

“The number of people who have had diabetes for more than 10 years has more than doubled in the last six or seven years,” Friedman says. The new findings are likely just the tip of the iceberg. If current diabetes rates continue, “we will see more and more people with diabetes and vision impairment.”

Preventing diabetes in the first place is key to preserving vision, he says. This includes losing weight (if necessary), eating a healthier diet, and getting regular exercise. But, he says, “if you have diabetes, make sure get your eyes checked, as this type of vision loss is preventable.”

Alan N. Carlson, MD, says that it is too early to say that the increase in vision problems is driven by diabetes. “Diabetes is on the rise and vision problems are on the rise, and patients with diabetes are more likely to have eye problems, but that is all we can say right now.” He is the chief of the corneal and refractive surgery services at the Duke Eye Center in Durham, N.C.

“Certainly people need to be aware of the risks of getting nonrefractive vision impairment down the road,” he says. “If there is a family history of certain diseases like macular degeneration, glaucoma, or diabetes, you should be seen more regularly by an eye doctor to make sure these diseases are caught earlier when they are much more treatable.”

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