Dr. Grossman’s Blog

A new study indicates that the carotenoids lutein and zeaxanthin may help improve vision under glare conditions such as bright sunlight or the beams of car headlights.

Scientists at the Vision Science Laboratory at the University of Georgia recently studied the relationship of lutein and zeaxanthin on macular pigment (MP), glare disability, and photostress recovery.

The macula helps filter damaging light rays. When the concentration of lutein and zeaxanthin in the macula is higher, the higher density of macular pigment enables the macula to absorb the light rays more efficiently.

Researchers studied forty healthy subjects (average age of 23.9) for six months, giving assessments at baseline, 1, 2, 4, and 6 months. Subjects were given 12mg daily of lutein and zeaxanthin supplements.

After 6 months, the lutein and zeaxanthin supplementation was shown to significantly reduce the negative effects of glare for both the visual performance tasks assessed for most of the subjects.

Read other studies about lutein and zeaxanthin, including their role in preventing macular degeneration and cataracts.

Learn more about natural leutein and zeaxanthin supplements

SOURCE: “Macular pigment and visual performance under glare conditions”, Stringham and Hammond, Optom Vis Sci., 2008 Feb;85(2):82-8

Homocysteine, an amino acid believed to contribute to heart attack, stroke and dementia, may also play a role in retinal damage and vision loss.  Homocysteine levels rise when folic acid levels drop, a common problem for Americans whose diets are often poor in folate-rich fruits, tomatoes, vegetables and grains.

Dr. Sylvia Smith, cell biologist at Medical College of Georgia (MCG), and Dr. Vadivel Ganapathy, chair of the MCG Department of Biochemistry and Molecular Biology are studying the consequence of slightly elevated homocysteine on the retina under a $1.8 million grant from the National Institutes of Health.  They want to learn the impact of elevated homocysteine levels on the extensive blood vessel and neuronal network of the retina; their preliminary evidence suggests that it isn’t good.

“You don’t have to be a cell biologist to see that there is a problem in this retina. It’s terribly disrupted,” Dr. Smith says, looking at images of a fragmented 10-layer retina exposed to high levels of homocysteine.  A healthy retina is “beautifully” organized, horizontally and vertically, she says.

Folate and vitamin B12 convert homocysteine to methionine, an amino acid essential to protein synthesis.  Dr. Ganapathy notes that people need only about 1 microgram per day of vitamin B12, which comes from microorganisms common in animals’ gastrointestinal tract. Strict vegetarians are typically the only Americans who have problems with B12 deficiency, he says. People need about 400 micrograms of folate daily. Pregnant women as well as those trying to become pregnant need at least double that.

Researchers are studying a mouse model with a slightly elevated homocysteine level that simulates a low-folate diet in humans; a version of the mouse that also has diabetes, which goes along with cardiovascular disease and retinopathy; and a second model of the rare genetic defect that results in extraordinarily high homocysteine levels.  These mice will be put on diets that elevate and lower folate levels, so that resultant homocysteine levels and the impact on the retina can be studied.

Researchers hypothesize that sustained elevation will compromise retinal function and degrade the once well-stratified tissue; in pilot studies, the researchers have shown that diabetes exacerbates this problem.

SOURCE:  Medical College of Georgia, “Impact of elevated homocysteine levels on vision under study,” Oct. 15, 2007.

Researchers in Italy have released a study indicating that nutritional supplements of bilberry and French maritime pine bark can help reduce intra-ocular pressure (IOP). While several factors contribute to the development of glaucoma, elevated IOP is one of the greatest risks. An improved ocular blood flow may help prevent glaucoma.

Authors of the study from the University of Chieti-Pescara in Italy studied thirty-eight subjects with intraocular hypertension. Twenty subjects were given bilberry and French maritime pine bark; eighteen subjects were not treated. The visual acuity, IOP, and ocular blood flow were measured at two, three, and six months. After two months, the group taking the supplements showed a decrease in the mean IOP. No side effects were observed and ocular blood flow improved.

Having reviewed the results, these researchers believe that food supplements of bilberry and pine bark may represent a safe preventative intervention for lowering the risk of developing glaucoma by supporting a healthier pressure in the eyes.

Read more research on glaucoma

Learn about bilberry and other natural supplements for healthy vision

SOURCE: “Effects of Mirtogenol on ocular blood flow and intraocular hypertension in asymptomatic subjects”, Robert Steigerwalt Jr., et al, Molecular Vision 2008; 14:1288-1292.