ABSTRACT

The visual system's functionality is influenced by various physiological factors, including accommodation and pupil dynamics. Caffeine, a widely consumed psychoactive substance, has known effects on the central nervous system, but its impact on ocular functions such as accommodation amplitude and pupil size remains underexplored. This study investigates the short-term effects of graded caffeine doses on the amplitude of accommodation (AOA) and pupil size among young adults.

A total of 60 participants were recruited and divided into three groups, receiving caffeine doses of 2.5 mg/kg, 3.75 mg/kg, and 5 mg/kg, respectively. Baseline AOA and pupil size measurements were taken, followed by post-consumption measurements at 30-minute intervals until values returned to baseline. AOA was assessed using the push-up method, while pupil size was measured with a pupillometer. Data were analyzed using paired-sample t-tests and Pearson correlation analysis.

The results demonstrated a significant increase in AOA and pupil size across all groups, peaking approximately 60-90 minutes post-consumption before gradually returning to baseline. However, there was no statistically significant correlation between caffeine dosage and the magnitude of changes in AOA and pupil size, suggesting individual physiological variations in response to caffeine.

These findings highlight caffeine’s transient influence on ocular accommodation and pupil dynamics, which may have implications for clinical eye assessments. Further research is recommended to explore the underlying mechanisms and assess caffeine’s effects across different age groups and habitual consumers.

KEYWORDS: Caffeine, Amplitude of accommodation, Pupil Size.