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LOS ANGELES -- Abnormal retinal microvasculature was tied to a higher risk of some types of stroke, researchers reported here.

People with abnormal retinal microvasculature -- including arteriovenous nicking, focal arteriolar narrowing, retinal micro-aneurysms, and retinal hemorrhage -- had a higher cumulative incidence of stroke within 15 years compared with those with normal microvasculature, according to Michelle Lin, MD, of Johns Hopkins University School of Medicine in Baltimore, and colleagues.

In a subanalysis of the large Atherosclerosis Risk in Communities (ARIC) study cohort presented at the American Academy of Neurology annual meeting, over 4% of those with abnormal microvasculature reported a stroke compared with only 1.9% of those with normal retinas (P<0.001).

"This is not surprising at all," commented the discussant for the study, Valerie Biousse, MD, of Emory University in Atlanta. "It goes very well within the concept of small vessel disease -- small vessel disease in the eye, small vessel disease in the brain. This makes a lot of sense."

The prospective ARIC study included 10,468 individuals between the ages of 45 and 65, all of whom underwent baseline retinal photography. A total of 673 strokes were reported among the cohort -- 578 ischemic strokes and 95 hemorrhagic strokes. Among ischemic strokes, the most common subtype was nonlacunar (292), followed by cardioembolic (172), and lacunar (114).

All retinal photographs were read by trained staff at a single center, which Lin cited as a strength of the study. However, she noted that some images were ungradable and the photographs captured only a small area of the retina, which may have led to an underestimate of the prevalence of microvasculature abnormality.

Using an adjusted model, the researchers found a positive association specifically with ischemic stroke and retinal microvasculopathy. However, this relationship extended only to lacunar stroke (HR 1.8, 95% CI 1.2 to 2.7). A dose-dependent relationship was also identified, with a higher risk for both ischemic and lacunar stroke tied to a larger amount of abnormal retinal microvasculatures.

Other subtypes of stroke were not significantly tied to retinal microvasculature:

• Nonlacunar: HR 1.3 (95% CI 0.9 to 1.6)
• Cardioembolic: HR 1.2 (95% CI 0.8 to 1.6)
• Hemorrhagic: HR 1.2 (95% CI 0.8 to 1.9)

"I believe that retinal imaging now allows direct visualization of the small vessel vasculature and neuronal tissues that may give insights into the pathogenesis of cerebrovascular disease, as well as the neurodegenerative disease," Lin said.

Biousse echoed this sentiment, highlighting that the findings are an important addition to everyday clinical practice, predicting that neurologists "will use this information."

"If this is really true, though, why are we not using it yet?" she questioned, explaining that the technology is still not widely available to many practicing neurologists. "The limiting factor remains this: which magic wand do we need to be able to measure and calculate the retinal microvasculature changes? We're almost there."

Lin said she was hopeful, given the rapid advancements in retinal imaging within the past decade -- for example, newer camera technology has allowed for greater mobility, even extending to smartphone applications that make it possible for more dissemination of retinal imaging to a wider group of patients across various settings, including underserved communities.

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