Caffeine Consumption and Dynamic Visual Acuity

Article: Coffee time: Caffeine improves reaction to moving targets 
Source: University of Waterloo, Optometry & Vision Science (Canada)
Published: December 1, 2021 

Widespread testimony supports the acute stimulating effect of caffeine consumption. Researchers in Canada conducted the first study to examine the effect of caffeine ingestion on dynamic visual acuity (DVA). They argue in favor of dynamic vision testing in the sense that "[t]esting visual acuity under dynamic conditions can provide more information about our functional performance in these [everyday] scenarios than traditional static visual acuity measurements alone." Since most of the objects we interact with in our environment are moving, dynamic visual acuity skills are especially important in daily activities. The study recruited 21 low-caffeine consumers aged early to mid-twenties to take part in a placebo-controlled, double-blind, and balanced crossover study. On two separate days, participants were divided into two groups, ingesting a capsule containing either caffeine (4 mg/kg) or a placebo; DVA was measured before and 60 minutes after ingestion. The researchers found that caffeine ingestion improved the accuracy of both horizontal and random motion paths of DVA. However, while caffeine ingestion was associated with faster reaction time for horizontal moving targets, it had no effect on improving reaction time for randomly moving targets. They infer that caffeine has an ergogenic effect to positively influence participants' stimulus processing. One of the authors remarks, "Our findings show that caffeine consumption can actually be helpful for a person’s visual function by enhancing alertness and feelings of wakefulness. This is especially true for those critical, everyday tasks, like driving, riding a bike or playing sports, that require us to attend to detailed information in moving objects when making decisions."

My rating of this study: ⭐

Redondo B, Jiménez R, Molina R, et al. "Effects of caffeine ingestion on dynamic visual acuity: a placebo-controlled, double-blind, balanced-crossover study in low caffeine consumers." Psychopharmacology.  238:3391-3398. 22 August 2021. https://doi.org/10.1007/s00213-021-05953-1