While eating your carrots won't necessarily prevent weak eyes, like your parents may have suggested, vitamin supplements and nutrition do play a part in keeping your eyes healthy. Glaucoma, an often painless compression of the optic nerve that carries impulses from the retina to the brain, may improve when consuming certain nutrients, but more studies are needed. Around 3 million Americans have glaucoma, the leading cause of blindness in African Americans, who develop the disease more frequently than Caucasians. Don't take vitamins or other supplements to prevent glaucoma without your medical practitioner's approval.
Types
Vitamins A, B1, B12, C and E have not been found to have any benefit in treating glaucoma, according to the Glaucoma Research Foundation. Experts consider some older studies that claimed benefit from B12 to be inadequate. Lutein and zeaxanthin, yellow pigments called xanthophylls, may also have some benefit in treating glaucoma. Vitamin C may reduce intraocular pressure, but only if massive amounts, which cause severe diarrhea and dehydration, are given, the GRF reports.
Mechanisms
Because lutein and zeaxanthin act as antioxidants, substances that reduce damage from free radicals, they may reduce oxidative damage around the optic nerve. B-complex vitamins may protect and repair damaged nerves, according to Macular Degeneration Health. B12 may protect the myelin sheath that insulates nerve cells.
Possible Benefits
In one 1992 Japanese study reported by Macular Degeneration Support, 1,500 micrograms of B12 daily for five years resulted in less vision loss and better control of the fluid pressure within the eye that compresses the optic nerve. In a 1998 University of Bologna study, a combination of omega-3 fatty acids and vitamins E plus B-complex vitamins widened the field of vision of 30 patients with glaucoma under good control with local therapy in 90 days.
Risks
Clinical trials on the effects of vitamins and other antioxidants such as lutein haven't proven of definite benefit in glaucoma. Long-term results of their use against glaucoma have also not been proven.
Considerations
Because glaucoma can cause permanent vision loss, studies that test vitamins and other substances are only practical if done as an adjunct to known effective medical drugs and treatments. Medications that reduce pressure in the eye either by decreasing the amount of fluid produced or by increasing drainage are known to be effective. Alternative treatments should be used only to promote general good health that might also benefit your eyes, not as a primary treatment, the University of Maryland Medical Center warns.
