Hypoglycaemia, or low blood sugar, is common, and is the single most preventable cause of brain damage at birth.
Research, published this month in the New England Journal of Medicine involving the University of Waterloo finds evidence that current guidelines on maintaining blood sugar levels in newborns with hypoglycaemia reduces their risk for brain damage.
Ben Thompson, an associate professor at School of Optometry and Vision Science in the Faculty of Science, led the project’s vision team, who tested the infants at two years of age for evidence of impairment affecting visual areas of the brain.
Until this study, no one had any empirical evidence showing whether current treatment guidelines were safe or correct,” says Thompson.
The study tracked more than four hundred infants. Those who developed low blood sugar levels, were treated to maintain a minimum blood sugar level above 47 milligrams per decilitre.
Thompson, an expert in human visual cortex development and plasticity, designed a test to assess whether two years later the children treated at birth had suffered any vision loss when compared with children who did not develop low blood sugar levels.
Testing children this young is tricky,” says Thompson. “We had to design a whole new test to encourage cooperation and keep their attention. This was a ground-breaking study on many levels.”
The test uses movement to elicit our visual tracking, or optokinetic, reflex, which develops early in infancy.
When you see a repeated pattern moving past you, such as train cars, your eyes smoothly track and follow part of the pattern – for example, a window. Once the window moves out of the visual range, the eyes quickly snap back to follow another part of the pattern or window.
Using moving patterns of dots presented in between entertaining cartoons, Thompson’s team manually recorded the children’s optokinetic reflex. By determining the proportion of dots moving in the same direction at which the reflex kicked in, the researchers were able to measure the ability of the brain to process movement.
Since the two-year-old low blood sugar group performed as well as the controls on this and other tests, the researchers concluded that intervention at the threshold of 47 milligrams per decilitre worked and avoided hypoglycaemic brain damage.
Thompson’s test now automatically records subjects’ eye movements and will be used to measure neurological damage in other groups in future studies.
The study was led by the Liggins Institute at the University of Auckland in collaboration with researchers from the Universities of Auckland and Canterbury and the Walkato District Health Board in New Zealand.
Professor Thompson’s vision team included co-authors Sandy Yu, Nabin Paudel, Nicola S. Anstice and Robert J. Jacobs.
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