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Fighting Retinitis-Related Vision Loss
May 4, 2010
3 Min Read
By Diane E. Alexander, Ph.D.
Retinitis pigmentosa (RP) is the name of a group of inherited eye diseases that result in poor night vision in adolescence, and the loss of side (midperipheral and far peripheral) vision in adulthood with tunnel vision as the outcome. As this disease progresses, patients lose their central vision, generally by the age of 60. RP has a prevalence of 1 in 4,000 people and an estimated 50,000 to 100,000 people are affected in the United States. Since no accepted medical or surgical treatment can stop the course of the disease, a number of studies have accessed the whether nutritional supplements could improve functional vision in RP patients or slow the progression of the disease. Lutein, a component of the macular pigment, is an essential nutrient that has been shown to have a protective effect on the macula. This protection stems from the antioxidant properties of lutein, and its ability to attenuate damaging blue wavelengths of visible light.
These beneficial properties were recently affirmed in a new study, published online in the Archives of Ophthalmology (2010;128(4):403-11). The findings offer new hope for the prevention of visual field loss in patients suffering from retinitis pigmentosa.
In this randomized, placebo-controlled, double blind study conducted by lead author Eliot Berson, M.D., Harvard Medical School, 225 non-smoking RP patients aged 18 to 60 years with received either 12 mg/d of FloraGLO® Lutein, supplied by Kemin Health, or a placebo tablet. All patients received 15,000 IU/d of vitamin A and throughout the study period were advised to eat one to two servings of oily fish per week to increase their intake of long chain omega-3 polyunsaturated fatty acids (PUFA).
Patients were supplemented over the course of four years, and their serum lutein levels, macular pigment optical density (MPOD), and visual field were assessed on a yearly basis. Results of the trial were as follows:
Mean serum lutein levels were higher in the lutein group as compared to the placebo group (p<0.001) at one year and were maintained over the course of four years.
The lutein group showed a significantly greater increase in macular pigment optical density (MPOD) over four years compared with the control group (p<0.001).
During the four years of supplementation, a decline in visual field area was apparent in all patients. However, a significantly lower decline in midperipheral visual field sensitivity was observed in the group supplemented with lutein (p=0.05) after four years.
When patients were categorized by lutein serum levels, patients in the highest quartile of serum lutein levels had a significantly decreased rate of midperipheral visual field sensitivity (p=0.01) loss compared with those in the lower 3 quartiles.
When patients were categorized by MPOD levels, the rate of decline of midperipheral visual field sensitivity was significantly slower among those in the highest quartile of change in MPOD versus the rate among those in the lower 3 quartiles (p=0.006).
No adverse effects of supplementation were noted.
Based on the randomized comparison, lutein supplementation saved on average 2.7 percent of midperipheral visual field sensitivity per year. Based on the change in serum lutein level, the savings would be 4.7 percent and based on change in MPOD, the savings would be 6.3 percent per year. Over the longer term, the authors estimated supplementation with FloraGLO lutein would preserve midperipheral visual field sensitivity among RP patients also taking a vitamin A supplement and eating an oily fish diet for three to 10 additional years.
Diane Alexander, Ph.D., is a technical service manager for Kemin Health ( Kemin.com ). Her work at Kemin focuses on providing technical expertise on Kemin Healths products, assisting prospective and current customers with developing product concepts, and overseeing trials to validate product efficacy. She received her bachelors degree in microbiology from Pennsylvania State University and Ph.D. in microbiology from Washington University in Saint Louis.
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