Caffeine Uptake into the Vitreous after Peroral Coffee Consumption

Abstract

Introduction: Caffeine and its metabolites have antioxidant activity, scavenging reactive oxygen species. Aim of our study was to measure caffeine concentrations in vitreous samples after peroral caffeine intake. Methods: This prospective study included patients scheduled for 23G pars plana vitrectomy with membrane peeling due to epiretinal membranes. The study was performed in two parts: In the first part patients were recruited into three different groups: group A consisted of habitual coffee drinkers, that agreed to drink coffee containing 180mg caffeine one hour before surgery (n=10), group B consisted of habitual coffee drinkers, that were not offered coffee before surgery (n=5), and group C consisted of non-habitual coffee drinkers, forming the control group (n=5). In the second part (group D) patients (habitual coffee drinkers) agreed to give additional blood serum samples for measurement of caffeine concentration. Harvested samples of vitreous (group A to D), epiretinal membranes (group A to C), and blood serum samples (group D) were examined for concentrations of caffeine with gas chromatography–mass spectrometry. Results: Samples of 40 eyes of 40 patients were harvested. The concentrations of caffeine in the vitreous samples were in group A of 1998 ng/ml +- 967 ng/ml and in group B of 1108 ng/ml +-874 ng/ml. In group C caffeine concentrations were below 176 ng/ml in all vitreous samples. Both, groups A and B, had significantly higher concentrations of caffeine in the vitreous samples than group C (p<0.002, p<0.01, Mann-Whitney-U test). Caffeine concentrations in epiretinal membranes were below the limits of detection. Correlation of caffeine concentrations between blood serum samples and vitreous samples in group D was high, with significantly higher caffeine concentrations in the blood serum. Conclusion: Coffee consumption leads to significant caffeine levels in the vitreous compared to patients in the control group, and caffeine concentrations in the vitreous showed a high correlation to blood serum concentrations of caffeine after peroral coffee consumption.