Study: AMD risk factors differ for drusen and pigmentary abnormalities

Factors such as alcohol consumption, diet and marital status varied in relation to risk for drusen or pigmentary abnormalities, study shows.

ByBob Kronemyer

A study investigating 5-year risk factors for the development of age-related macular degeneration found differences between the risk factors for the development of drusen and pigmentary abnormalities.

For example, alcohol consumption was found to decrease the risk of drusen formation and to increase the risk of pigmentary abnormalities, according to the study, based on a random sample of participants in the Reykjavik Eye Study.

Married participants were also found to have less risk of soft drusen, while single people had less risk of hypopigmentation compared with those who were widowed or divorced.

Dietary fiber-rich vegetable intake was also a factor for AMD. Those who consumed vegetables one to two times a week or less while between the ages of 40 and 60 years had a marked increased risk of drusen, compared with those who consumed dietary fiber-rich vegetables four to seven times a week.

Likewise, infrequent meat consumption in people between the ages of 20 and 60 years resulted in an increased risk of soft drusen, as opposed to those who ate such products four to seven times a week. However, less frequent consumption of meat and meat products was found to be protective for pigmentary abnormalities.

Major Step Forward

“Identifying factors that might delay late AMD for some years would be a major step forward,” wrote Arsaell Arnarsson, MSc, and colleagues, at the Department of Ophthalmology at the University of Iceland in Reykjavik, in the American Journal of Ophthalmology.

Unlike in many other large risk studies of AMD, smoking was not significantly associated with the disease. “The effect of smoking on developing AMD is partly masked by selective mortality,” the authors said.

The population-based, prospective cohort baseline examination for the study of age-related eye disease was performed in September and October 1996. A follow-up examination and interviews took place 5 years later, in September and October 2001. Of the 1,045 subjects examined at baseline, 846 were seen 5 years later.

Subjects filled out a comprehensive lifestyle and food frequency questionnaire and underwent an eye exam. The investigators also took fundus stereo color photographs and used a standard grading system to study the 5-year incidence of drusen, pigmentary abnormalities and AMD.

Alcohol influence

To calculate the effect of alcohol consumption on incidence risk for early age-related maculopathy, participants were divided into three groups: those who had never drank alcohol (14%), those who drank alcohol less than once a month (68%) and those who consumed it more frequently (18%).

The odds ratio of developing any of the eight evaluated characteristics in the never-drank group was 1.00. But in the other two groups (less-than-once-a-month and more-than-once-a-month consumption), the odds ratio of acquiring soft drusen was 0.47 and 0.40, respectively; large distinct drusen, 0.45 and 0.69; large indistinct drusen, 0.53 and 0.28; all soft drusen, 0.48 and 0.34; hyperpigmentation, 1.93 and 2.52; hypopigmentation, 1.09 and 1.10; pigmentary abnormalities, 1.37 and 1.42; and early age-related maculopathy, 1.65 and 1.98.

Marital status

The effect of marital status (with the divorced/widowed group having an odds ratio of 1.00 for all characteristics) could be either a benefit or a liability for the single group and married group, depending on the specific characteristic. The odds ratio of acquiring soft drusen was 0.72 for the single group and 0.45 for the married group; large distinct drusen, 0.90 and 0.79, respectively; large indistinct drusen, 1.58 and 0.82; all soft drusen, 1.04 and 0.49; hyperpigmentation, 0.96 and 0.84; hypopigmentation, 0.34 and 0.82; pigmentary abnormalities, 0.39 and 0.83; early ARM, 0.82 and 1.34; and geographic atrophy, 0.51 and 0.99.

Fiber-rich vegetables

Early AMD was also associated with the frequency of eating dietary fiber-rich vegetables (tomatoes, red peppers and cucumbers) at three different time periods in the subjects’ life: age 20 to 40, age 40 to 60, and baseline. For all three time periods and characteristics, the odds ratio was 1.00 for a frequency of four to seven times a week.

For all soft drusen, the odds ratio was 1.63 for consuming vegetables two to three times a week in the 20 to 40 age range, 2.06 in the 40 to 60 age range, and 1.34 for baseline. For vegetables one to two times every 2 weeks, the odds ratio was 1.12, 2.52 and 1.43, respectively.

For all pigmentary abnormalities, the odds ratio was 1.37 for consuming vegetables two to three times a week in the 20 to 40 age range, 0.81 in the 40 to 60 age range, and 1.46 for baseline.

For more information:

Fridbert Jonasson, MD, the corresponding author of this study, can be reached at Department of Ophthalmology, University of Iceland, Landspitalinn, 101 Reykjavik, Iceland. Dr. Jonasson has no direct financial interest in the products discussed in this article, nor is he a paid consultant for any companies mentioned.

Reference:

Arnarsson A, Sverrisson T, Stefánsson E, et al. Risk factors for five-year incident age-related macular degeneration: The Reykjavik Eye Study. Am J Ophthalmol. 2006;142:419-428.

Bob Kronemyer is an OSN Correspondent based in Elkhart, U.S.A.