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Senior Citizen Health & Medicine
Vision Loss Risk Factors for Senior Citizens: fish
good, tobacco bad, hormone therapy neutral
Three articles in
JAMA look at Age-Related Macular Degeneration Risks
 July 10, 2006 - Eating fish frequently may be
associated with decreased chances of developing age-related macular
degeneration, while smoking nearly doubles the risk for this common
cause of vision loss and hormone therapy appears to have no effect,
according to three articles in the July issue of the Archives of
Ophthalmology, one of the JAMA/Archives journals. All three studies
involved senior citizens, since AMD is the leading cause of blindness in
older people.
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July 2, 2006 - The Food and Drug Administration has
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is a significant advance, since other drug treatments of AMD have
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Age-Related Macular Degeneration Researchers Focused
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Betty White Urges Seniors to Get Serious About
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Seniors with Macular Degeneration More Likely to Have
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April 11, 2006 - Older patients with advanced
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Age-related macular degeneration (AMD) occurs when
the macula, the area at the back of the retina that produces the
sharpest vision, begins to deteriorate. The condition affects
approximately 30 percent of Americans age 75 years and older, with 6 to
8 percent developing advanced cases, according to background information
in one of the articles.
It is the most prevalent cause of vision loss and
blindness in the elderly population. Researchers have hypothesized that
many of the risk factors for cardiovascular disease, including
atherosclerosis or blocked arteries, may also contribute to the
development of AMD, possibly by affecting blood flow to the eye.
In the first study, Johanna M. Seddon, M.D., Sc.M.,
of the Massachusetts Eye and Ear Infirmary, Boston, and colleagues
studied genetic and environmental risk factors for AMD in 681 elderly
male twins. The men underwent an examination by an ophthalmologist,
filled out a food questionnaire and participated in a telephone
interview to assess other risk factors, including demographics, smoking,
alcohol consumption and physical activity habits. AMD was diagnosed
using photographs of the inner eye.
Of the 681 men, 222 (average age 75.9 years) had
intermediate or late-stage AMD and 459 (average age 74.5 years) had no
AMD or were in the very early stages.
● Those who currently smoked had a 1.9-fold
increased risk of AMD and those who had smoked in the past had a
1.7-fold increased risk.
● Those who ate more fish and more omega-3
fatty acids (found in salmon and other fish) were less likely to have
AMD.
● The greatest reduction in risk was seen
among individuals who ate two or more servings of fish per week.
● The benefits of eating more omega-3 fatty
acids were most apparent among those who consumed less linoleic acid, an
omega-6 fatty acid, suggesting that the proper balance of fats is key,
the authors write.
"About a third of the risk of AMD in this twin
study cohort could be attributable to cigarette smoking, and about a
fifth of the cases were estimated as preventable with higher fish and
omega-3 fatty acid dietary intake," they conclude.
"Age-related macular degeneration is a common eye
disease in older persons, smoking is a common avoidable behavior and
dietary habits are modifiable; therefore, a proportion of visual
impairment and blindness due to AMD could be prevented with attention to
healthy lifestyles."
Editor's Note: This study was funded by a grant
from the National Institutes of Health, Bethesda, Md.; the Foundation
Fighting Blindness Inc., Owings Mills, Md.; DSM Inc., Parsippany, N.J.;
the Retirement Research Foundation, Chicago; the Massachusetts Lions Eye
Research Fund Inc., Northboro; and the Epidemiology Unit Research Fund,
Massachusetts Eye and Ear Infirmary, Boston.
Eating Fish Protects Against Macular
Degeneration
In a second study, Brian Chua, B.Sc., M.B.B.S.,
M.P.H., Westmead Millennium Institute and Vision Co-operative Research
Centre, Syndney, Australia, and colleagues examined the association
between dietary fat intake and AMD risk in 2,895 Australians age 49
years or older, beginning in 1992-1994.
At the beginning of the study and again five years
later, participants had a comprehensive eye exam that included
photographs of the retina. They also filled out a questionnaire with
data about food types and portion sizes consumed, including specific
information about margarines, butters, oils and supplements.
Of the 2,335 participants who participated in the
five-year follow-up, 158 had developed early AMD and 26 late-stage AMD.
After adjusting for other factors that may influence risk, including
smoking, age, sex and vitamin C intake, those in the group with the
highest intake of polyunsaturated fat had a 50 percent reduced chance of
developing early AMD compared with those who ate the least.
● Those who ate fish once a week had reduced
risk of early AMD by 40 percent compared with those who ate fish less
than once per month, and
● those who ate fish three or more times per
week also had reduced risk for late-stage AMD.
Contrary to previous studies showing an increased
risk for AMD with higher unsaturated fat intake, no link was found
between AMD and consumption of butter, margarine or nuts, which all
contain high levels of unsaturated fats.
"To explain our findings, we suggest that
insufficient essential fatty acid intake could result in abnormal
retinal metabolism and cell renewal," the authors write.
"Studies have shown cardioprotective benefits of
monounsaturated fatty acids in the Mediterranean diet and that diets
high in n[omega]-3 fatty acids, particularly docosahexaenoic acid,
derived largely from fish, may protect against retinal oxidation and
degeneration.
"Our finding that at least weekly fish consumption
was protective against incident early age-related maculopathy provides
support for this hypothesis."
Hormone Therapy Does Not Affect
Age-Related Vision Loss
Postmenopausal hormone therapy does not appear to
increase or decrease the overall risk of AMD among women, although
combination hormones may slightly reduce the chances of developing
certain risk factors or types of the condition, according to a third
report in the same issue.
Mary N. Haan, M.P.H., Dr.P.H., University of
Michigan, Ann Arbor, and colleagues studied 4,262 women age 65 years and
older who were part of the Women's Health Initiative Sight Exam Study,
part of the larger Women's Health Initiative clinical trial of hormone
therapy.
Of those, 1,627 were in the estrogen-only group of
the study, with 48.1 percent taking hormones and 51.9 percent taking
placebo. The other 2,635 women were in the combination hormone trial;
52.3 percent of those participants were taking estrogen plus progestin
pills and 47.7 percent received placebo.
Participants underwent eye assessments and retinal
photography at the beginning of the study, between April 2000 and June
2002.
After an average of five years of follow-up, 21
percent of the women had developed AMD.
Neither combination nor estrogen-alone therapy was
found to be associated with developing AMD.
Among women in the combination trial only, active
hormone therapy was associated with a slightly reduced risk of
developing soft drusen-deposits in the eye that may precede AMD-and also
lower odds of having neovascular AMD, a less common form of the
condition in which blood vessels grow underneath the retina, impairing
vision.
"We conclude that treatment with hormones does not
influence the occurrence of early AMD," the authors conclude.
"As an exception, a possible protective effect was
found for soft drusen or neovascular AMD in relation to combined equine
estrogens plus progestin."
Editor's Note: The WHI program is supported by
the National Heart, Lung and Blood Institute, U.S. Department of Health
and Human Services (this study is an ancillary study to the WHI CT and
Observational Study); and support for the evaluation of macular
degeneration in women recruited into the WHISE Study was provided by
Wyeth Ayerst Laboratories. Dr. Musch has been a consultant to Iridex,
Inc., and MacuSight, Inc.
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