Females under the age of 75 years whose blood levels of vitamin D are high appear to have a reduced risk of developing AMD (Age-Related Macular Degeneration), researchers from the University of Buffalo, New York, wrote in Archives of Ophthalmology.

Macular degeneration is when the patients start losing their central vision - objects directly in front of them are harder to see, making such tasks as reading, writing, recognizing faces and driving much more difficult. The macular, or macula lutea is an oval-shaped yellow spot close to the center of the retina, in the eye. Macular degeneration, caused by damage to the retina, mainly affects elderly individuals. It is the main cause of partial-blindness among patients over the age of 50 years. Even though central vision is affected, because the patient still has peripheral vision, other activities in daily life are usually still possible to do.

The authors wrote:

"Age-related macular degeneration (AMD), a chronic, late-onset disease that results in degeneration of the macula, is the leading cause of adult irreversible vision loss in developed countries. Age-related macular degeneration affects approximately 9 percent (8.5 million) of Americans aged 40 years and older."

Amy E. Millen, Ph.D., and team set out to find out whether serum 25(OH)D blood levels were linked to age-related macular degeneration risk. They gathered data on 1,313 females who had participated in the Carotenoids in Age-Related Eye Disease Study, part of the Women's Health Initiative Observational Study.

The authors wrote:

"Serum 25(OH)D is the preferred biomarker for vitamin D status, as it reflects vitamin D exposure from both oral sources and sunlight."

After making adjustments for several AMD risk factors, they could not identify any significant link between vitamin D levels and early or advanced AMD.

Among 968 females aged less than 75 years whose serum 25(OH)D was high, the risk of developing early AMD was significantly lower, the researchers observed. However, among the 319 older females with higher serum 25(OH)D, there was a very slight increase in AMD risk.

The women under 75 with the highest vitamin D levels were found to have a 59% lower risk of developing early AMD compared to those with the lowest levels.

The authors wrote that milk, fish, fortified margarine and fortified cereals were among the top food sources of vitamin D. They found no link between self-reported direct sunlight exposure and AMD risk.

The researchers concluded:

"This is the second study to present an association between AMD status and 25(OH)D, and our data support the previous observation that vitamin D status may potentially protect against development of AMD. More studies are needed to verify this association prospectively as well as to better understand the potential interaction between vitamin D status and genetic and lifestyle factors with respect to risk of early AMD."

"Vitamin D Status and Early Age-Related Macular Degeneration in Postmenopausal Women"
Amy E. Millen, PhD; Rick Voland, PhD; Sherie A. Sondel, MS; Niyati Parekh, PhD; Ronald L. Horst, PhD; Robert B. Wallace, MD; Gregory S. Hageman, PhD; Rick Chappell, PhD; Barbara A. Blodi, MD; Michael L. Klein, MD; Karen M. Gehrs, MD; Gloria E. Sarto, MD, PhD; Julie A. Mares, PhD; for the CAREDS Study Group
Arch Ophthalmol. 2011;129(4):481-489. doi:10.1001/archophthalmol.2011.48

Written by Christian Nordqvist