Vitamin C and IOP
Most studies show that Vitamin C reduces IOP. The trick is giving enough Vitamin C.
My sources for this article are:
Alternative Medicine Review (subscription required) Volume 6, Number 2,2001, edited by Kathleen A. Head, ND.
Nutrition and Glaucoma: Do Supplements Reduce IOP ? by David Bennett BSc (Hons), MCOptom, for The Association of Optometrists Ireland.
There are several postulated mechanisms for ascorbate’s ability to lower IOP. In high doses, it acts as a potent osmotic agent. Vitamin C’s ability to halt lipid peroxidation has also been hypothesised to play a role. Supplementation with vitamin C is also believed to increase aqueous humour drainage by reducing the viscosity of hyaluronic acid in the trabecular meshwork.
Most studies, some of which were controlled, have found the supplement to successfully reduce IOP.
David Bennett says,
"In one report, a single dose of 500mg/kg ascorbic acid reduced IOP in all of 39 patients with COAG by an average of 16mmHg. Also, ascorbic acid 100-150mg/kg, three to five times daily, resulted in almost normal IOPs in 15 out of 16 patients by 45 days."
He doesn't include the source for this (it is available by request), but I think he is using the same source quoted by Kathleen A. Head.89 (see below)
He also says, "Some of these patients were uncontrollable with acetazolamide and 2% pilocarpine," but the Vitamin C was effective for them. His references are available by request but are not part of the published article. However I am fairly sure his sources are 90, 91.
In the body of his paper, David Bennett gives one source that I did not see in Kathleen Head's paper. He says,
"In his 1980 dissertation at New York University, Ben C. Lane, a doctoral student in ophthalmology, found in a study of 60 people that increasing their average vitamin C intake from 75mg to 1200mg reduced IOP by one-third."
Kathleen Head makes the same statement as Bennett, and she provides the reference.
"Researchers first examined the effect of high dose IV vitamin C on animals and then humans, and found it successfully decreased IOP. IV doses used were in the range of 1 g/kg body weight; oral doses used were half that (500 mg/kg body weight)."89
Here are some other statements I obtained from a combination of the two articles:
Those with chronic open-angle glaucoma responded the most dramatically to Vitamin C.
The higher the initial IOP, the greater the drop after ascorbate (Vitamin C).
Decreases in pressure were maintained for as much as eight hours.
All but one patient experienced decreased IOP during a two-week trial of divided doses.
One study of oral ascorbate did not find it effective at lowering IOP in glaucoma. The researchers, however, used only 500 mg twice daily.
And these same researchers successfully lowered IOP with topical use of a 10-percent aqueous solution of vitamin C in a better follow-up study.90,91
In high doses Vitamin C acts as a potent osmotic agent.88
Vitamin C’s ability to halt lipid peroxidation has also been hypothesized to play a role.88
Vitamin C has also been found, in vitro, to stimulate synthesis of hyaluronic acid in trabecular meshwork from glaucomatous eyes.78
Ascorbate has also been found to reduce the viscosity of hyaluronic acid and increase outflow through the trabeculum. 92
We all know that high doses of Vitamin C can cause mild gastric upset and diarrhea. But these disappear in about 3-4 days. All the articles mentioned this effect. In my own case, gradually increasing the dose eliminates this problem. I find it very simple to completely avoid the possibility of this side effect. The thing I find harder is tapering down gradually after using a high dose of Vitamin C. I find my body gets used to it and doesn't want to do without it. I really do feel the benefit when taking those higher amounts of Vitamin C. However, I have not tried the levels suggested by these studies since I was diagnosed with glaucoma. I plan to do that in the near future when I can monitor my IOP very carefully.
Here is a one table from Kathleen A. Head's article. I have not asked for permission to reproduce this, so I may have to remove it. But for now, here it is:
And here is a partial list of references from Kathleen A. Head's article:
- 78. Schachtschabel DO, Binninber E. Stimulatory effects of ascorbic acid in hyaluronic acid synthesis of in vitro cultured normal and glaucomatous trabecular meshwork cells of the human eye. Z Gerontol 1993;26:243-246
- 88. Aleksidze AT, Beradze IN, Golovachev OG. Effect of the ascorbic acid of the aqueous humor on the lipid peroxidation process in the eye in primary open-angle glaucoma. Oftalmol Zh 1989;2:114-116. [Article in Russian]
- 89. Virno M, Bucci MG, Pecori-Giraldi J, Missiroli A. Oral treatment of glaucoma with vitamin C. Eye Ear Nose Throat Monthly 1967;46:1502-1508.
- 90. Linner E. Intraocular pressure regulation and ascorbic acid. Acta Soc Med Upsal 1964;69:225-232.
- 91. Linner E. The pressure lowering effect of ascorbic acid in ocular hypertension. Acta Ophthalmol (Copenh) 1969;47:685-689.
- 92. Liu KM, Swann D, Lee P, Lam KW . Inhibition of oxidative degradation of hyaluronic acid by uric acid. Curr Eye Res 1984;3:1049-1053.