This audio article is from VisualFieldTest.com.
Read the full article here: https://visualfieldtest.com/en/vitamins-c-and-e-in-glaucoma-antioxidants-revisited
Test your visual field online: https://visualfieldtest.com
Excerpt:
IntroductionGlaucoma is a progressive eye disease that damages the optic nerve and leads to vision loss; it affects over 70 million people worldwide and is a leading cause of irreversible blindness (). A major risk factor is high intraocular pressure (IOP), but damage can occur even at normal pressure. Over time, scientists have noticed that oxidative stress (cell damage from free radicals) may contribute to glaucoma by harming retinal ganglion cells and the eye’s drainage tissues () (). This has led to interest in antioxidant nutrients – particularly vitamins C and E – as possible protective agents in glaucoma. Vitamin C (ascorbic acid) and vitamin E (tocopherols) fight oxidation in the body, and they are highly concentrated in the eye. For example, ascorbate levels in the aqueous humor of the eye are roughly 15 times higher than in blood (), suggesting it plays a natural protective role. In healthy eyes these high antioxidant levels may guard against free radicals from light exposure and metabolism (). In glaucoma patients, however, the eye’s antioxidant defenses often appear lower: several studies report reduced vitamin C in the eye fluid of people with glaucoma (). This review will summarize the evidence—both old and new—on vitamins C and E in glaucoma. We will look at laboratory and animal studies, population surveys and clinical trials, and consider both immediate effects and long-term outcomes. Key questions include: Can high-dose vitamin C lower eye pressure? Does taking vitamin C or E supplements actually slow glaucoma? Are there risks (like kidney stones or bleeding) from megadoses? How do these supplements interact with medications? We will also compare getting vitamins from foods versus pills, note any differences seen in various populations, and finally give practical advice to patients thinking about antioxidant supplements for glaucoma. Vitamin C and GlaucomaVitamin C (ascorbic acid) is a water-soluble antioxidant abundant in fruits and vegetables. It helps regenerate vitamin E and neutralize free radicals. In the eye, high ascorbate levels help protect the lens and retina from light and oxygen damage (). Experiments in animals suggest ascorbate can increase fluid outflow from the eye – for example, low eye ascorbate was found in rabbits with glaucoma-like high pressure (). In lab models, topical or systemic vitamin C has been shown to lower IOP: for instance, applying vitamin C to the eye or injecting it into the bloodstream of rabbits and patients has produced temporary pressure drops (). This effect is thought to come from vitamin C’s ability to relax the eye’s drainage channels, improving fluid outflow. Interestingly, vitamin C levels in the eye can be boosted by taking supplements. In cataract patients without glaucoma, giving 2 g of vitamin C by mouth raised aqueous humor ascorbate from ~1350 to ~1860 μmol/L, while 20 g given intravenously raised it to ~2387 μmol/L (). In other words, high-dose vitamin C (especially IV) greatly increases antioxidant levels inside the eye, much more so than diet alone. Whether this actually translates into lasting glaucoma benefit is unclear. A few small studies and older reports noted that large doses of vitamin C – given orally, topically or by IV – could briefly lower IOP in glaucoma patients (). However, these were not large trials and such treatments are not standard care. We simply note that acutely taken vitamin C can reduce eye pressure in some studies (), but this has not proven to halt or reverse glaucoma. Obs
