To investigate the changes in the subfoveal choroidal thickness measured by enhanced depth imaging optical coherence tomography after a single administration of a cup of coffee in healthy subjects.
In this prospective study, 62 healthy subjects (study group) who received a cup of 100 mL Turkish coffee (57 mg caffeine/100 mL) and 54 healthy subjects (control group) who received the same amount of water were enrolled. In the study group, the participants underwent enhanced depth imaging optical coherence tomography scanning at baseline, and at 5 minutes, 30 minutes, 1 hour, 2 hours, 3 hours, 4 hours, and 6 hours after coffee drinking. The participants of the control group simultaneously underwent enhanced depth imaging optical coherence tomography scanning. Subfoveal choroidal thickness measurements were performed on both groups at another time.
Baseline choroidal thickness was 328 ± 79 μm in the study group and 311 ± 79 μm in the control group (P = 0.381). In the study group, choroidal thickness was significantly lower at 5 minutes, 30 minutes, 1 hour, 2 hours, 3 hours, and 4 hours after coffee drinking when compared with the baseline measurement (P < 0.001, for all); however, there were no significant differences between the measurements at 6 hours and 24 hours after coffee drinking and the baseline measurement (P = 0.113 and P = 0.342, respectively). In the control group, no significant difference was found between each choroidal thickness measurement (P > 0.05, for all).
The findings of this study revealed that drinking of a cup of coffee causes a significant decrease in choroidal thickness for at least 4 hours after coffee drinking.