Effects of Black Currant Anthocyanins on Intraocular Pressure in Healthy Volunteers and Patients with Glaucoma

Purpose: The purpose of the present study was to elucidate the effects of oral administration of black currant anthocyanins (BCACs) on intraocular pressure (IOP) in both healthy subjects and patients with glaucoma. Methods: (1) A placebo-controlled, double-masked, crossover study (n = 12) was conducted, during which BCACs (50 mg/day) or placebos were orally administered to 12 healthy subjects once daily for 4 weeks. (2) A total of 21 glaucoma patients (BCACs, n = 12; placebo, n = 9) treated with a single antiglaucoma medication who had participated in a previous study (a randomized, double-masked, placebo-controlled trial, Ophthalmologica 2012) were selected and analyzed. Systemic blood pressure, pulse rates, IOP, and Humphrey visual-field mean deviation (MD) (program 30-2, SITA standard) were evaluated. Results: (1) A statistically significant decrease in the mean IOP was observed at 2 weeks (P = 0.002, paired t-test) and 4 weeks (P = 0.039, paired t-test) from the baseline in BCAC-treated healthy subjects. This decrease, however, was not observed in the placebo group. In addition, at 2 weeks after the baseline, changes were also statistically significant between the groups (P = 0.027, paired t-test). (2) Intergroup and between-group analyses revealed statistically significant decreases in mean IOP in the glaucoma patients taking BCACs (P = 0.027, paired t-test; P = 0.024, unpaired t-test) at 24 months after the baseline. In addition, mean changes of MD deterioration were significantly less in BCAC glaucoma patients administered with BCACs at 12 months (P = 0.017, Mann-Whitney U test) and 18 months (P = 0.050, Mann-Whitney U test) after the baseline. No clinically significant changes were observed in systemic blood pressure or pulse rates in either trial. Conclusions: Our results suggested that oral administration of BCACs may induce a beneficial decrease in IOP levels in healthy subjects as well as in patients with glaucoma.