Abstract
Purpose :
Higher doses of caffeine have been shown to impact passive saccadic eye movements, yet the effects on active saccadic eye movements, such as those involved in complex visual search or reading text, have not been extensively studied. Understanding the effects of caffeine on eye movements during complex visual tasks like reading is crucial, particularly for graduate students who often rely on caffeine to enhance their academic performance.
Methods :
15 graduate students (mean age of 28.53 + 4.25 years; 11 males) from the Chicago College of Optometry with a history of daily caffeine use and no history of binocular vision disorders were randomly assigned to receive either a 450 mg rice flour pill (n = 8) or an identical looking 200 mg caffeine pill (n = 7). Eye movements were measured using the RightEye Sensorimotor System at baseline and 30 minutes after pill consumption. Passive eye movements were measured using the built-in Functional Vision EyeQ protocol involving simple visual targets, while active eye movements were measured using the Reading EyeQ protocol, involving self-paced reading of an age-appropriate long passage and “yes” or “no” comprehension questions.
Results :
Our results revealed a significant improvement with caffeine compared to placebo in the targeting accuracy of horizontal saccades (milliseconds; z = -2.791, p = .028), fixation dispersion (millimeters; z = -2.371, p = .018), and comprehension scores (percentage correct; z = -2.226, p = .026). There was no statistically significant difference in the velocity of horizontal saccades, reading rate, number of fixations, fixation duration, or number of regressions between groups during the reading task. Habitual caffeine use, including the average number of cups per day and the number of days per week, did not influence the outcomes.
Conclusions :
Overall, this study indicates a potential beneficial effect of caffeine in the accuracy of eye movement and reading comprehension. These findings support prior research linking eye movement alignment with text and improved comprehension scores. Further research is warranted to explore the dose effect of caffeine on various aspects of eye movements and cognitive performance across diverse populations and visual tasks.
This abstract was presented at the 2024 ARVO Annual Meeting, held in Seattle, WA, May 5-9, 2024.