Supplements and Glaucoma
By Leo Semes, OD, FAAO
A review of the literature on supplements for common eye diseases published in 2006 by West et al did not find support for the use of supplements in managing glaucoma. Since then, however, the tide appears to be changing. Complementary and alternative medicine has moved from the public realm (perhaps even from out of the shadows) to a place in evidence-based medicine. According to the Age-Related Eye Disease Study (AREDS), supplements have demonstrated efficacy in slowing the progression of age-related macular degeneration (AMD) in selected cases (Sangiovanni et al, 2009; AREDS Research Group, 2008).
What about other eye diseases and disorders? Vitamin and mineral supplementation has not been shown to be beneficial for diabetic retinopathy or cataract, but recent information on glaucoma suggests there may be a role for their use. For example, higher vitamin C intake was associated with a reduced risk for glaucoma (Klein et al, 2008). Very high doses of vitamin C produce a positive osmotic effect on aqueous production, and this may be the mechanism by which it is protective in glaucoma.
At the molecular level, oxidative stress is at the root of the pathophysiology of glaucoma. Regulating calcium channels at the cellular level may be beneficial for regulating cellular function, if not intraocular pressure (IOP), in glaucoma. A recent proposal suggests that reducing oxidative stress at the lamina cribrosa may limit mitochondrial dysfunction and help preserve cellular and visual function (McElnea et al, 2011).
Somewhat closer to home, we manage glaucoma by lowering IOP, the one modifiable risk factor. Although alternative strategies, such as neuroprotection and enhanced blood flow, have generally proven less than spectacular, one recent study (Steigerwalt, 2010) has demonstrated improved IOP lowering and improved blood flow when the oral supplement Mirtogenol (Horphag/Indena) was added to the prostaglandin analog latanoprost (Xalatan, Pfizer). The study monitored the IOPs of 79 patients who had asymptomatic ocular hypertension. While latanoprost alone lowered mean IOP from a baseline of 37.7mmHg to 27.2mmHg within 4 weeks, the combination of latanoprost and the supplement produced mean IOPs of 23.0mmHg; however, this result occurred after 24 weeks of treatment.
In addition, diastolic blood flow velocity gradually increased with treatment duration in both groups. From 12 weeks onward, the diastolic component with combination treatment was higher than with individual treatments. Doppler imaging to ascertain blood flow measured the peak systolic flow velocity and end diastolic flow velocity of the central retinal artery.
Mirtogenol is a proprietary formulation consisting of 80mg of Mirtoselect standardized bilberry extract (Vaccinium myrtillus L, Indena). It is composed of flavonoids and standardized to contain 36% anthocyanins (conforming to USP 31 on “Powdered Bilberry Extract”). Mirtogenol tablets further contain 40mg of French maritime pine bark extract, Pycnogenol (Horphag Research), which consists of flavan-3-ols standardized to 70% ± 5% procyanidins (conforming to the USP 31 on “Maritime Pine Extract”).
Complementary medicine strategies to improve blood flow in neurodegenerative diseases, such as glaucoma, have been suggested in the past. It appears that Mirtogenol may possess that capacity as well as the ability to lower IOP.
Keep in mind, however, that patients are unlikely to volunteer information regarding supplement intake (Rhee et al, 2002; Wan et al, 2010), so remember to ask. CLS
For references, please visit www.clspectrum.com/references.asp and click on document #192.
Dr. Semes is a professor of optometry at the UAB School of Optometry. He is also a consultant or advisor to Alcon, Allergan, Optovue, and Zeiss.