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Professors team up for vision research

Windows to the brain

(March 23, 2000, Gazette)

It’s impossible for six-month-old Jagger to read a standard eye chart but researchers at MUN have devised a new test that should permit accurate measurement/diagnosis of vision in the critical first few years of life.

By Tanya Bolduc
SPARK student

Look around and it seems like half of the people you see are wearing glasses these days, not to mention contact lenses. More and more people are availing of a new laser surgery technique to correct their vision problems and cataract surgery is no more painful than getting a tooth filled. It certainly seems that at the rate medical technology is going, it will only be a matter of time before everyone will be able to claim 20/20 at the DMV.

Think again, warn Drs. Russell Adams and Mary Courage, Psychology.

“People don’t often realize that it’s not just the eyes that control vision, but also certain visual areas of the brain. Problems can’t always be fixed at the eye level,” said Dr. Adams. “Vision problems, particularly in children, are often brain problems. It’s important to catch vision problems early because permanent changes to the cells of the brain simply isn’t possible after five or six years of age.

“Vision is highly organized in the nervous system with different routes laid out for different types of stimulation,” he explained.

“And while we know what these routes are and where they are in adults and animals, we have yet to understand when they develop in human beings, specifically during the first few years of life.”

As researchers in infant vision studies, Drs. Adams and Courage seek to understand the ways in which brain function is modified by early visual experience in both normally and abnormally developing infants. To determine how parts of the brain and eye develop together, Dr. Adams along with Avery Earl, a computer consultant in Psychology, developed a new and comprehensive test that looks at pattern recognition in infants.

Using a contrast sensitivity test, Dr. Adams presents his test subjects, children ranging from 10 week premature to three years of age, with a series of large cards comprised of striped circles of varying contrasts. A subject’s fixation on one of the circles indicates that the subject has developed a pathway sensitive to that particular level of contrast.

“Contrast sensitivity is itself one of the most sensitive measures of human vision,” he said. “It is the best single test for telling us about visual and neurological processes. But most importantly, it allows you to make an educated guess at where problems may lie, whether it’s in the eye or in the brain.

“The contrast sensitivity test will help us to develop new tests for diagnosis down the road and if these tests help us to scan for possible vision problems, that’s great. That’s our hope, that we could start testing early with the best technology available.”

Dr. Adams, with the help of PhD candidate Jamie Drover, has already developed and published a growth chart based on the data collected from normally developing infants and children.

“What we’ve found thus far we tried to apply to kids we suspect are at risk for poor vision or poor neurological development such as very premature babies and children with Down Syndrome.”

Another project that the team is working on seeks to better understand visual information processes and how they relate to early memory retention. This may have implications for the early detection of cognitive delay.

This aspect of the research utilizes two tests – the Fagan Test and the Paired Comparison Procedure – to measure the amount of time visual information is retained in the brain. In each experiment the subject is exposed to a pair of similar visual stimuli. Over pre-determined periods, one of the stimuli is changed slightly.

“Typically, the baby fixates on the altered stimulus,” explained Dr. Courage. “We know that babies prefer the new over the familiar and patterns over the plain. What we’re looking for are differences in the way they recognize patterns. For example, we look at whether they are what we call short-lookers or long-lookers.

“In other words, how long it takes for them to notice a change in the pattern. This reflects the speed at which they are processing information.”

Dr. Courage warns that speed in processing may not necessarily be an indication of intelligence.

Dr. Courage hopes that the data she is collecting will one day help to in the early diagnosis of General Developmental Delay or more specific problems such as Attention Deficit Hyperactivity Disorder.

Dr. Adams and Dr. Courage are also collaborating with Dr. James Friel, Biochemistry. Dr. Friel is investigating antioxidants and nutrition as ways to combat brain disorders, including vision problems, caused by oxygen deprivation and respiratory diseases in very premature infants. All three are working closely with neonatologists Dr. Khalid Aziz and Dr. Wayne Andrews of the Janeway Children’s Hospital.

The infant vision research currently being conducted by Drs. Adams and Courage boasts the highest number of newborns tested in the world. It also boasts regular support in the form of funds provided by the Natural Science and Engineering council of Canada (NSERC), the Medical Research Council (MRC), and the Janeway Foundation.

SPARK, Students Promoting Awareness about Research Knowledge, is a NSERC funded program designed to encourage writing about research.