Glaucoma, the second most common cause of blindness in the United States, affects around 3 million Americans, although only half of them realize they have it, according to the Merck Manuals Online Medical Library. Glaucoma, which causes progressive damage to the optic nerve, is at least partly caused by elevated intraocular pressure, or IOP. Lutein, a yellow pigment that acts as an antioxidant, might help in treating eye disorders, but it's not clear that people with glaucoma will benefit.
Causes
Fluid in the eyeball maintains its shape and acts as a cushion. If pressure rises, damage to the optic nerve, which sends signals to the brain, can occur, but this isn't the whole story in glaucoma. The pressure in the eye normally stays below 21 mm/Hg. While many people have elevated IOP, only around 10 percent develop glaucoma over a five-year period, according to Merck, and around 33 percent of people with glaucoma have normal IOP. People with glaucoma have abnormally high amounts of glutamate, a chemical that transmits nerve impulses to the brain around the optic nerve. Small amounts of glutamate are released as cells die off and are normally removed by other cells. When glutamate overwhelms the cleanup cells, glaucoma accelerates, website Macular Degeneration Support explains.
Lutein Actions
Lutein, found mostly in green leafy vegetables and other green and yellow vegetables, acts as an antioxidant. Antioxidants protect cells from damage by free radicals, which destroy cells. Lutein, which is found in high concentrations in the eye, also absorbs blue light, which can damage the back of the eye.
Potential Benefit
Lutein might protect the nerve layer of the retina, the light-sensitive layer of cells that lines the back of the eyeball, from oxidative damage. Low levels of lutein in the nerve bundle that transmits signals to the brain might be an early sign of glaucoma, according to website MD Support.
Considerations
Studies have not yet shown a strong connection between lutein and glaucoma. A study published in the October 2003 issue of the "American Journal of Epidemiology" by Harvard researchers found that antioxidants in general did not improve glaucoma, with the possible exception of lutein and zeaxanthin, but the connection was not strong enough to establish a definite reduction in glaucoma for those with a diet high in lutein.
References
- Merck Manuals Online Medical Library: Glaucoma
- Glaucoma Research Foundation: Nutrition and Glaucoma
- All About Vision: Lutein and Zeaxanthin
- "American Journal of Epidemiology"; "Antioxidant Intake and Primary Open-Angle Glaucoma: A Prospective Study"; Jae Kang et al; October 2003
- Macular Degeneration Support: A New Look At Eye Health
