Regular vitamin C

“We found that cells in the retina need to be ‘bathed’ in relatively high doses of vitamin C, inside and out, to function properly,” says author Henrique von Gersdorff, PhD, senior scientist at the Oregon Health & Science University in Portland.
“Because the retina is part of the central nervous syst, this suggests that there’s likely an important role for vitamin C throughout our brains, to a degree we had not realized before.”
Using goldfish eyes, the researchers noted that GABA-type receptors (receptors that respond to neurotransmissions) in the retinal cells stopped functioning properly when vitamin C was roved.
Considering that retinal cells are a form of brain cell, the researchers postulated that GABA receptors elsewhere in the brain also require vitamin C for proper function. They concluded that because vitamin C is a natural antioxidant, it likely helps to preserve and protect both brain and retinal cells from prature breakdown.
The findings also could have major clinical implications for patients with glaucoma and epilepsy, because both conditions are induced by nerve cell dysfunction in the retina and brain secondary to improper GABA receptor function.
“For example, maybe a vitamin C-rich diet could be neuroprotective for the retina and for people who are especially prone to glaucoma,” Dr. von Gersdorff said.
Calero CI, Vickers E, Moraga Cid G, et al. Allosteric modulation of retinal GABA receptors by ascorbic acid. J Neurosci. 2011 Jun 29;31(26):9672-82.