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Eye on fetal alcohol spectrum disorders

May 2009
Laura S. Marshall,

Diagnosis of a medical condition whose symptoms vary can be tricky: Without specific tests, it can take a long time to pin down the cause – time in which the condition can reduce quality of life or even worsen.

Such is the case with fetal alcohol spectrum disorders (FASD), caused by prenatal exposure to alcohol. Experts at the Mayo Clinic in Rochester, Minn., say early diagnosis reduces the risk of long-term problems for children with FASD. But it’s not as easy, quick or definitive as a blood test. Physicians can screen for growth impairment, facial malformations and heart defects as the baby grows; language development and IQ tests also are used, and genetic testing can rule out other disorders. And the majority of children with FASD show no physical manifestations of the disorder but are affected by the brain injury and resulting behavioral and learning deficits, which may not show up at birth.

James N. Reynolds, professor of pharmacology and toxicology at Queen’s University in Kingston, Ontario, Canada, with help from neuroscience master’s students Loriann Williams and Rebecca Titman, demonstrates the eye-movement test that he and his group use to identify children with fetal alcohol spectrum disorders. Courtesy of Jeff Drake/Queen’s University.

But now a Canadian research team has come up with an objective test to help doctors find FASD. James N. Reynolds, a professor in the pharmacology and toxicology department and at the Centre for Neuroscience Studies, both at Queen’s University, has been studying the effects of alcohol on brain function for nearly 20 years. He said recent studies have considered eye-movement behaviors as a potential research and diagnostic tool in fetal alcohol spectrum disorders. “Eye movements can be viewed as a ‘window’ into the brain and can be used to reveal deficits in brain function,” he said.

Enter the head-mounted video-based infrared eye tracker from Iscan Inc. of Woburn, Mass. The company’s systems have a variety of applications, from advertising research, drug impairment testing and brain research to pointing systems for users with disabilities, said Rikki Razdan, president.

The unit used in this study consists of a headband-mounted system that uses a video camera system to view the subject’s eye with the help of a transparent dichroic mirror and low-level IR illumination from a single LED. A second video camera system captures what the subject is viewing with specialized line-of-sight optics, and data is collected and analyzed using dedicated software.

Reynolds said that he and his team chose Iscan’s unit because it was the first truly portable system they found – and portability was key because the study was carried out in nine communities in different parts of Canada.

“Many children affected by FASD live in rural or remote areas of the country,” he said. “They do not have access to sophisticated neuroimaging equipment found in major hospitals and research centers, and, therefore, access to specialized diagnostic assessment is difficult, if not impossible.

“The real breakthrough in this study was getting out of the laboratory and going where the kids live.”

In eye-movement tests, Reynolds noted, children with fetal alcohol spectrum disorders exhibit much longer reaction times and make more errors than children without FASD. “Reaction time” is the time that elapses between the appearance of a visual target and the first eye movement; an “error” occurs when a child makes eye movements in the wrong direction relative to the instruction for the task.

Other influences

Testing children from around the country provided a chance to investigate the possible influence of age, gender, medications and co-morbidities, and other factors on eye-movement behaviors in children with FASD. “Overall,” Reynolds said, “the analysis indicates that deficits in eye-movement control in children with FASD are independent of these other factors.” That is to say, they are a result of prenatal exposure to alcohol.

Current clinical assessment and screening protocols for FASD do not include eye-movement tests, but that’s the next step. “What we need to do now is engage in a prospective study that integrates eye-movement testing into the diagnostic process,” he said, “to determine the sensitivity and specificity of deficits in eye-movement control for identifying children affected by prenatal exposure to alcohol.”

Fetal alcohol syndrome is an incurable condition, according to the Mayo Clinic. Symptoms include distinctive facial features; heart defects; limb and joint deformities; slow growth; impaired vision or hearing; small head circumference and brain size; mental retardation and delayed development; and behavioral problems. In the US, up to 40,000 babies are born each year with some kind of alcohol-related damage.

Biophotonicsfacial malformationsfetal alcohol spectrum disordersNews & Featurestoxicology

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