Scientists at UCSF assessed the use of statins and aspirin among more than 300 elderly patients with age-related macular degeneration, or AMD, a common condition among people over 70. About one in eight cases of AMD deteriorates into what is called wet AMD, the leading cause of irreversible severe vision loss in older people.
The scientists found that those patients already taking statins were half as likely as those without statins to develop the more severe wet AMD, caused by the growth of new blood vessels underneath the retina. Those already on aspirin were about 40 percent less likely to develop this new blood vessel growth, technically called choroidal neovascularization (CNV).
The research is reported in the April issue of the American Journal of Ophthalmology.
"Standard treatments for wet AMD often result in stabilization of vision loss, rather than improved vision, so it's important to identify treatments that may prevent the disease," said Jacque L. Duncan, MD, assistant professor of ophthalmology at UCSF and senior author of the study.
Of the few earlier studies of the possible relationship between statins and either early or late AMD, three supported an association and one did not. All these studies involved relatively small numbers of people with wet AMD, Duncan said.
"This study is probably the strongest support we can get for the benefits of statins and aspirin against AMD," Duncan said. "A randomized controlled trial is unlikely to occur, because it would withhold statins and aspirin from the control group, and these drugs have been shown to save lives."
Some patients were on statins alone, some on aspirin alone, and some on both, Duncan noted. A statistical analysis found that both statin use and aspirin use were independently associated with reduced risk of CNV.
Earlier studies had suggested that statins' ability to lower cholesterol levels in the blood may account for their protective effect against macular degeneration, since some evidence suggests that fat deposits in eye membranes may lead to AMD. But Duncan and her colleagues found no association between cholesterol levels after statin treatment and wet AMD.
The most likely, but still unproven, explanation involves the anti-inflammatory properties of both statins and aspirin, Duncan said. Tissue studies of patients with CNV reveal chronic inflammatory cells and other evidence of inflammation. Statins inhibit production of proteins involved in inflammation and reduce the role of immune cells in inflammation. They also are antioxidants, which have been shown to reduce risk of CNV in AMD patients.
"There are lots of good reasons to be on statins and aspirin," Duncan concludes. "This study suggests yet another potential benefit. Although we are not sure of the mechanism, these drugs appear likely to have a protective effect against the leading cause of irreversible severe vision loss in older people."
The study also supported earlier findings that development of the harmful CNV is significantly more common among smokers.
Lead author of the study is Hilary L. Wilson, MD, first-year resident in ophthalmology at Loma Linda University and former medical student at UCSF. Co-authors of the paper and collaborators in the research are Daniel M. Schwartz, MD, associate professor of ophthalmology at UCSF; Charles E. McCulloch, PhD, professor of epidemiology and biostatistics at UCSF; and Hilarey R. F. Bhatt, MD, assistant professor of medicine at the UCSF-affiliated Veteran Affairs Medical Center.
The research is supported by the National Eye Institute, by Research to Prevent Blindness, and grants from That Man May See, Inc. and The Foundation Fighting Blindness.
Journal
American Journal of Ophthalmology