PORTLAND, Oregon — Changes to the eye’s tiny blood vessels could predict a higher risk for a dangerous circulation condition in the legs that, in turn, can lead to amputation, heart attack or stroke, according to a new study released Wednesday.

Researchers studied 9,390 adult participants of a large long-term study about atherosclerosis in four communities in Mississippi, North Carolina, Minnesota and Maryland. Atherosclerosis is the buildup of fat, cholesterol and calcium in arteries. Each participant had retinal photographs, images of the inside of their eyes, taken between 1993 and 1995.

During a 19-year follow-up, 304 developed peripheral artery disease, or PAD, a narrowing or blockage of the arteries in the leg, which required hospitalization or a procedure to open narrowed leg vessels. Of those participants, 92 had the most severe form of PAD, called critical limb ischemia, or CLI, resulting in ulcers on the leg, gangrene or the need for amputation.

When investigators adjusted the results to account for common PAD risk factors, such as diabetes, they found any retinal abnormalities that showed up in the scans indicated a 2.16 times greater risk of PAD developing in the follow-up period. For CLI, it was a 3.41 times greater risk.

Individual retinal abnormalities – including bleeding, yellow spots from the breakdown of lipids, and areas of blood protruding from vessels in the back of the eye, called microaneurysms – also were associated with the risk of PAD or CLI.

PAD is a serious medical condition affecting 8.5 million Americans, but many people don’t know they have it. It is similar to coronary artery disease and caused by plaque buildup that narrows and blocks peripheral arteries, those in the outer regions away from the heart.

The condition’s most common symptoms are cramping, pain or tiredness in the leg or hip muscles while walking or climbing stairs.

People with PAD have a higher risk of heart attack or stroke. The body relies on healthy blood flow to heal wounds, but PAD can prevent healing and can lead to ulcers and, in severe cases, tissue death. So, left untreated, PAD also can lead to gangrene and amputation.

The study’s authors were Chao Yang and Kunihiro Matsushita, M.D., Ph.D., both of Johns Hopkins Bloomberg School of Public Health in Baltimore. Their work was presented at the American Heart Association’s Epidemiology and Prevention/Lifestyle and Cardiometabolic Health 2017 Scientific Sessions.