The findings provide new information on the potential impact of even minimal alcohol consumption on high-risk human activities that rely on sharp visual and visuomotor control, such as driving, piloting, or working on heavy machinery.
In previous studies, eye movements and vision were affected only at blood alcohol concentration (BAC) approaching the legal driving limit.
A study by a research team based at NASA’s Ames Research Center in California found for the first time that hand-eye coordination is dramatically more sensitive to alcohol, with some coordination measures disrupted by more than 20 percent at a BAC level of 0.015 per cent
“Our findings provide a warning story that the subjective experience of drunkenness is often not consistent with objective impairment of sensorimotor coordination. In other words, most people feel impaired after one drink, but they are significant,” said Terence Tyson, the study’s first author. published in The Journal of Physiology.
Driving can be affected by drinking only small amounts of alcohol, although the driver may feel well and be within legal limits, Tyson added.
To reach this conclusion, the researchers measured the eye movements, reactions of the students and the BAC volunteer, several times during the day while performing a specially designed task, before and after drinking alcohol.
Coincidentally, volunteers were assigned a mixed drink that contained a certain amount of alcohol, achieving either a higher (0.06 percent) or lower (0.02 percent) peak BAC level, so they were unaware of exactly how much they drank per day.
The researchers then calculated 21 different ocular measures that were shown to assess neural processing in specific areas of the brain that contribute to different components of eye movement and pupil response.
Study participants were men and women, mostly over the age of 20, who drank an average of 1-2 drinks per week.
The researchers made sure that the participants slept all night the night before and asked them to refrain from consuming alcohol and caffeine for several nights in a row before the test.
In addition to this finding specific for alcohol-induced damage, this research further demonstrated how a specially designed collection of noninvasive ocular measurements can be used to measure mild processing deficits in the brain.
In future studies, researchers plan to examine how their eye measurements are affected by other types of neurological conditions, such as those caused by degenerative diseases or toxic exposure.
NASA is interested in developing sensitive but non-invasive methods to detect mild damage.