ABSTRACT
Purpose: The effects of coffee intake on the ratio of stromal and luminal components in the choroid and the underlying mechanism remain unclear. This prospective cross-sectional study aimed to explore how coffee intake affects the choroidal component ratio and circulation. Methods: Forty-nine right eyes of healthy adult volunteers were evaluated as the coffee intake group. Thirty-two right eyes of healthy volunteers served as the control group. The participants consumed 185 mL of coffee or water, respectively, and the systemic hemodynamics, enhanced-depth imaging optical coherence tomographic (EDI-OCT) images, and foveal mean blur rate (MBR), an indicator of blood flow velocity, were recorded at baseline and after coffee or water intake. The EDI-OCT images were binarized using ImageJ software, and subfoveal choroidal thickness (SCT) and whole, luminal, and stromal choroidal areas were calculated. Results: In the coffee intake group, significant decreases in SCT and luminal area peaked at 60 minutes after intake (both P < 0.001), whereas a significant increase in MBR peaked at 30 minutes (P < 0.001). No significant stromal area fluctuations were observed. SCT and luminal area fluctuations exhibited a significant positive correlation (r = 0.978, P < 0.001). Significant negative correlations of luminal area fluctuations with MBR fluctuations were observed by stepwise regression analysis (r = -0.220, P < 0.001). The control group exhibited no significant fluctuations. Conclusions: Coffee-induced choroidal thinning may result mainly from a reduction in the choroidal vessel lumen, and this vessel lumen reduction correlated with an increased choroidal blood flow velocity after coffee intake. These coffee-induced changes in choroidal component ratio and circulation should be considered when evaluating choroids.