Written by Angeline A. De Leon, Staff Writer. Of the 38 patients with open angle glaucoma, those who supplemented with 50 mg of black current anthocyanins for 24 months had significantly less MD deterioration at the end of 24 months as well as a significant increase in blood circulation to the retina at the end of 18 months compared to placebo.
One of the major causes of irreversible blindness globally, glaucoma involves damage to the optic nerve (nerve connecting eye to brain) caused by sustained fluid pressure inside the eye (elevated intraocular pressure, IOP) 1. The most common form of glaucoma, open-angle glaucoma (OAG), involves blood circulatory disturbances at the optic nerve head (round area in the back of the eye) 2, a condition which most antiglaucoma medicines and surgeries aim to modify, but show limited success in treating. Newer research suggests that for such diseases involving disrupted ocular blood circulation, anthocyanins (a type of polyphenol) found in black currants may be beneficial in altering the hemodynamics of ocular blood flow 3. Black currant anthocyanins (BCACs) demonstrate an ability to improve certain visual functions 4, and in the context of OAG, oral administration of BCACs has been found to increase blood flow at the optic nerve head (ONH) and change concentrations of plasma endothelin-1 (associated with the pathogenesis of glaucoma) 3. To understand whether BCACs might alter ocular blood circulation and thereby prevent visual field deterioration in patients with OAG, researchers at Sapporo Medical University (2012) conducted a study looking at the effects of BCACs on OAG disease progression.
A randomized, double-blind, placebo-controlled, single-center trial was carried out using a group of 38 patients with a clinical diagnosis of OAG. Subjects were randomly designated to receive daily doses of either BCACs (50 mg/day) or placebo for 24 months. At baseline and every 6 months during the 24-month period, researchers assessed IOP, ocular blood flow, and Humphrey visual field mean deviation (MD, a measure of total visual field loss).
Results of the study showed that mean change in MD deterioration from baseline to 24 months was significantly less in the BCAC group vs. placebo (unpaired t test, p = 0.039). In addition, mean change in ocular blood circulation within the ONH (inferior temporal peripapillary retina specifically) was found to be significantly higher in the BCAC group, relative to placebo, at 18 months (unpaired t test, p = 0.01). No significant changes in IOP were reported during the 24-month period.
Based on study findings, researchers conclude that the transfer of BCACs into ocular tissues has a meaningful impact on the eye health of patients with OAG. By increasing ocular blood flow and improving the visual field of perception, oral administration of BCACs offers a safe and promising supplement for glaucoma patients and those with compromised, deteriorating vision.
Source: Ohguro H, Ohguro I, Katai M, et al. Two-year randomized, placebo-controlled study of black currant anthocyanins on visual field in glaucoma. Opthalmologica. 2012; 228: 26-35. DOI: 10.1159/000335961.
Copyright © 2012 S. Karger AG, Basel
Posted August 7, 2017.
References:
- Group CN-TGS. Comparison of glaucomatous progression between untreated patients with normal-tension glaucoma and patients with therapeutically reduced intraocular pressures. American journal of ophthalmology. 1998;126(4):487-497.
- Ogawa T, Ogawa A, So K. Target intraocular pressure and risk factors for progression of visual field loss in primary open-angle glaucoma. Nippon Ganka Gakkai Zasshi. 2002;106(8):488-493.
- Ohguro I, Ohguro H, Nakazawa M. Effects of anthocyanins in black currant on retinal blood flow circulation of patients with normal tension glaucoma. A pilot study. 2007.
- Nakaishi H, Matsumoto H, Tominaga S, Hirayama M. Effects of black currant anthocyanoside intake on dark adaptation and VDT work-induced transient refractive alteration in healthy humans. Alternative Medicine Review. 2000;5(6):553-562.
