Comparison of the Short-Term Effect of Coffee, Energy Drink, and Water on the Eyes in Young Healthy Subjects

Purpose: We aim to compare the short-term effects of energy drink (ED), coffee, and water on the eyes of young healthy male subjects.Materials and methods: The right eyes of 30 healthy male subjects were included in this study. We measured the intraocular pressure (IOP), mean arterial pressure (MAP), retinal thickness (RT), choroidal thickness (CT), and retinal nerve fiber layer (RNFL) thickness using spectral domain optical coherence tomography (SD OCT). The measurements for RT and CT were taken at the fovea as well as 1,500 mu m nasal and temporal to the fovea. The measurements of the subjects were performed on the first day before water consumption and at 30 minutes and 60 minutes following intake of 250 mL of water. Measurements were repeated at the same regime on the second day after drinking 250 mL of coffee containing an equal concentration of caffeine in ED (37.5 mg) and on the third day after drinking 250 mL of ED. Repeated measures one-way analysis of variance test was used for statistical analysis.Results: No significant difference was found for ocular perfusion pressure (OPP), MAP, RT, and IOP between the measurements taken on three consecutive days (p>0.05 for all). The CT values for the central, nasal, and temporal segments were significantly reduced in 0-30 and 0-60 minutes following coffee and ED intake (the range of p-value was <0.001-0.027).Conclusions: Both coffee and ED intake caused acute and significant decreases in CT that persisted for one hour in young healthy male subjects. The impact of ED intake on CT was attributed mainly to its caffeine content.