Increased Dependence on Saccades for Ocular Tracking with Low Dose Alcohol

Previous studies have shown that certain features of oculomotor performance are impaired at or slightly below the legal limit for driving in most U.S. States (0.08% Blood Alcohol Concentration or BAC). Specifically, alcohol impairs saccadic velocity and steady-state tracking at levels between 0.04% and 0.1% BAC. Here we used a suite of standardized oculometric measures to examine the effect of ultra-low levels of alcohol (down to 0.01% BAC) on steady-state tracking. Our high-uncertainty tracking task reveals that the smooth pursuit system is highly sensitive to BAC, with impairmentextrapolating back to BAC levels at or below 0.01%. BAC generates a dose dependent increase in reliance on the saccadic system that maintains overall steady-state tracking effectiveness at least up to 0.08% BAC, albeit with a significant decrease in smoothness.