Taking aspirin regularly can more than double the risk of wet age-related macular degeneration (AMD), a leading cause of blindness in older people, according to a 15-year study.
The researchers found a significant link between taking aspirin once or more per week and wet AMD that could not be explained by a history of heart disease or smoking.
Wet AMD is caused by the growth of abnormal blood vessels in the retina and leads to a progressive blurring of central vision.
The researchers, led by Dr Gerald Liew from the University of Sydney in Australia, followed over 2,000 regular and non-regular aspirin users for 15 years, comparing rates of wet AMD.
At five, 10 and 15 years rates of wet AMD among non-regular users were 0.8%, 1.6% and 3.7%, respectively, compared with rates of 1.9%, 7%, and 9.3% among regular users - defined as taking aspirin once or more per week.
The authors of the study, published in the journal JAMA Internal Medicine, said: “Currently, there is insufficient evidence to recommend changing clinical practice, except perhaps in patients with strong risk factors for neovascular AMD… in whom it may be appropriate to raise the potentially small risk of incident neovascular AMD with long-term aspirin therapy.”
However, they added that any decision on whether to stop aspirin treatment was “complex and needs to be individualised”.
Commenting on the findings, US experts Dr Sanjay Kaul and Dr George Diamond, from Cedars-Sinai Medical Center in Los Angeles, wrote in the journal: “From a purely science-of-medicine perspective, the strength of the evidence is not sufficiently robust to be clinically directive.”