Researchers from the Kanuni Sultan Suleyman Education and Research Hospital, Department of Ophthalmology demostraded that choroidal thickness changes after a single administration of coffee in healthy subjects. Vural et al. included in this study 62 healthy subjects who received a cup of 100 mL Turkish coffee and 54 healthy subjects (control group) who received the same amount of water. 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. However, there were no significant differences between the measurements at 6 hours and 24 hours after coffee drinking and the baseline measurement.
Vural AD, Kara N, Sayin N, Pirhan D, Ersan HB. Choroidal thickness changes after a single administration of coffee in healthy subjects. Retina. 2014;34(6):1223-8.