THURSDAY, Feb. 28 (HealthDay News) -- People suffering from age-related macular degeneration (AMD) have twice the risk of dying from heart attack or stroke, Australian researchers report.
The degenerative eye disease is the most common cause of untreatable blindness among older adults in developed countries and affects the center of the retina at the back of the eye, which is essential for tasks such as reading and driving.
"We found a positive long-term link between AMD and subsequent cardiovascular and stroke mortality in a population of older Australians," said lead researcher Dr. Paul Mitchell, from the Centre for Vision Research in the Department of Ophthalmology at the University of Sydney. "This was particularly increased for late-blinding cases."
"Both ophthalmologists and general practitioners should be aware of this potential link and need to consider appropriate management of traditional vascular risk factors, such as smoking, blood pressure, blood lipids in their patients with AMD," Mitchell said.
In the study, Mitchell's team studied 3,654 people aged 49 years old and older. Five years later, 2,335 people were re-examined, and after 10 years, 1,952 were re-examined.
The report is published in the Feb. 28 online issue of the British Journal of Ophthalmology.
The researchers found that for people under 75, when the study began, early AMD was linked with a doubling of their risk of dying from heart attack or stroke over the next 10 years.
For those with late-stage AMD at the start of the study, their risk of dying from heart attack increased fivefold, and their risk of dying from stroke increased 10 times, Mitchell's team found.
"While AMD, particularly in its late stage, occurs in people of relatively older ages, it may be associated with an increased vascular risk," Mitchell said. "This could, in part, reflect shared risk factors such as smoking."
One expert noted that because AMD is a vascular problem, it is not surprising that it is associated with increased cardiovascular risk.
"Age-related macular degeneration and atherosclerotic vascular share common risk factors that include hypertension, hyperlipidemia and smoking," said Dr. Gregg C. Fonarow, a professor of cardiology at the University of California, Los Angeles.
In addition, systemic inflammation may increase the risk of AMD and atherosclerosis, Fonarow said.
"Just as having peripheral vascular disease is associated with an increased risk of cardiovascular disease through common risk factors, having AMD is associated with an increased risk of cardiovascular disease and mortality," Fonarow said.
"Patients and physicians should recognize that patients diagnosed with AMD are more likely to have underlying cardiovascular disease and subsequent events and take appropriate steps to lower that risk though lifestyle changes and cardiovascular protective therapies," Fonarow advised.
In another report in the same issue of the journal, British researchers concluded that genes that control the production of chemicals involved in inflammation may play a significant role in AMD.
One gene variation associated with the gene that produces an inflammatory chemical called interleukin 8, was significantly more common among people with AMD, the researchers found. This gene variant has been previously linked with inflammatory diseases and cancer.
If these findings hold up, the researchers think it could lead to genetic screening for AMD and possibly the development of medications to treat the disease.
For more on AMD, visit the U.S. National Eye Institute.
SOURCES: Paul Mitchell, M.D., Centre for Vision Research, Department of Ophthalmology, University of Sydney, Australia; Gregg C. Fonarow, M.D., professor, cardiology, University of California, Los Angeles; Feb. 28, 2008, British Journal of Ophthalmology