Changes in Choroidal Component Ratio and Circulation After Coffee Intake in Healthy Subjects

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.

Figure 1.

Two-dimensional color maps of the MBR measured using LSFG, EDI-OCT imaging, and converted binary images of a healthy 23-year-old man consuming 185 mL of canned coffee (148 mg caffeine). (A–C) LSFG images at baseline (A) and at 60 minutes (B) and 300 minutes (C) after coffee intake. A false-color composite map at a rectangle (5° × 5°) around the macula was created using the LSFG software. Rapid and slow blood flow areas are indicated as red and blue areas, respectively. The average MBR was 7.5 (arbitrary units) at the baseline; it increased to 12.8 at 60 minutes after coffee intake and then decreased to 8.2 at 300 minutes after intake. (D–F) EDI-OCT images at baseline (D) and at 60 minutes (E) and 300 minutes (F) after coffee intake. On white-on-black EDI-OCT images, the lumen is depicted as black with a low signal, and the stroma is depicted as white. (G–I) Converted binary images of the EDI-OCT images shown in panel D (G), panel E (H), and panel F (I). The choroidal thickness decreased slightly at 60 minutes after coffee intake relative to the baseline and then increased at 300 minutes. Note that the luminal area was constricted at 60 minutes relative to the baseline but was re-expanded at 300 minutes.

Figure 2.

Changes in hemodynamic parameters in all eyes of the coffee intake group (49 eyes) and the control (water intake) group (32 eyes). In all 49 eyes of the coffee intake group (closed circle), significant fluctuations were observed in the SBP, DBP, MAP, mean ocular perfusion pressure, HR, and MBR (all P < 0.001). Compared with the baseline, SBP and MAP were significantly increased at 30, 60, and 120 minutes (all P < 0.036); mean ocular perfusion pressure was significantly increased at 30 and 60 minutes (both P < 0.011); and DBP was significantly increased at 30 minutes (P = 0.001) after coffee intake. HR was significantly decreased at 30, 60, and 120 minutes after coffee intake relative to the baseline (all P < 0.013). These values returned to the baseline levels at 300 minutes (all P = 1.000). The MBR was significantly increased at 5, 30, 60, 120, and 180 minutes (all P < 0.019) and returned to the baseline level at 240 minutes (P = 0.667). In the control group (open circle), there were no significant fluctuations in any of the hemodynamic parameters during the observation period (all P > 0.117). Asterisks indicate significant changes from the baseline. Error bars indicate standard deviation.

Figure 3.

Changes in OCT parameters in all eyes of the coffee intake group (49 eyes) and the control (water intake) group (32 eyes). In all 49 eyes of the coffee intake group (closed circle), significant fluctuations were observed in the SCT, whole choroidal area, luminal area, and L/W ratio (all P < 0.001). The SCT, whole choroidal area, luminal area, and L/W ratio were significantly decreased at 5, 30, 60, 120, 180, and 240 minutes after coffee intake (all P < 0.001). These decreases peaked at 60 minutes, and the values increased thereafter. The SCT and L/W ratio returned to the baseline levels at 300 minutes (both P > 0.073). The whole choroidal area and luminal area returned to values near the baseline at 300 minutes, although these values still differed significantly from the baseline (both P < 0.027). There were no significant fluctuations in the stromal area and CRT (both P > 0.910). In the control group (open circle), there were no significant fluctuations in any of the OCT parameters during the observation period (all P > 0.194). Asterisks indicate significant changes from the baseline. Error bars indicate standard deviation.

Figure 4.

Differences in hemodynamic parameters between the coffee intake test and the control (water intake) test of the same subjects (32 eyes). The line graphs show the mean and standard deviation of the coffee test value minus the control test value at each time point in the 32 eyes that underwent both the coffee intake test and the control test. Paired testing at each time point between the two tests was performed. Compared with the respective values of the control test, significant increases in the coffee intake test were observed in SBP and MAP at 30, 60, and 120 minutes (all P < 0.024); in the MBR at 30 and 60 minutes (both P < 0.016); in MOPP at 30 and 120 minutes (both P < 0.046); and in DBP at 120 minutes (P = 0.026). There were no significant differences at any time points in HR (all P > 0.790). Asterisks indicate significant differences between the coffee intake test and the control test.

Figure 5.

Differences in OCT parameters between the coffee intake test and the control (water intake) test of the same subjects (32 eyes). The line graphs show the mean and standard deviation of the coffee test value minus the control test value at each time point in the 32 eyes that underwent both the coffee intake test and the control test. Paired testing at each time point between two tests was performed. Compared with the control test, significant decreases in the coffee intake test were observed in SCT, whole choroidal area, luminal area, and L/W ratio at all time points after the baseline (all P < 0.050). There were no significant differences at any time point in the stromal area and central retinal thickness (all P > 0.794). Asterisks indicate significant differences between the coffee intake test and the control test.