Eyes may someday be used to assess if you're more likely to develop a stroke, researchers reported Monday in the American Heart Association journal Hypertension.

Researchers from the National University of Singapore tracked stroke occurrence for an average 13 years in 2,907 patients with high blood pressure who had not previously experienced a stroke.

At the start of the study, each participant had photographs taken of the retina, the light-sensitive layer of cells at the back of the eyeball. Damage to the retinal blood vessels attributed to hypertension, called hypertensive retinopathy, evident on the photographs was scored as none, mild,moderate or severe.

During the follow-up, 146 participants experienced a stroke caused by a blood clot and 15 by bleeding in the brain.

After adjusting for several stroke risk factors such as age, sex, race, cholesterol levels, blood sugar, body mass index, smoking and blood pressure readings, the researchers found the risk of stroke was 35 percent higher in those with mild hypertensive retinopathy and 137 percent higher in those with moderate or severe hypertensive retinopathy.

Even in patients on medication and achieving good blood pressure control, the risk of a blood clot was 96 percent higher in those with mild hypertensive retinopathy and 198 percent higher in those with moderate or severe hypertensive retinopathy, they said.

"The retina provides information on the status of blood vessels in the brain," said Mohammad Kamran Ikram, lead author of the study and assistant professor in the Singapore Eye Research Institute at the National University of Singapore. "Retinal imaging is a non-invasive and cheap way of examining the blood vessels of the retina."

Worldwide, high blood pressure is the single most important risk factor for stroke. However, it's still not possible to predict which high blood pressure patients are most likely to develop a stroke.

Ikram said that it's "too early to recommend changes in clinical practice" about assessing the stroke risk. "Other studies need to confirm our findings and examine whether retinal imaging can be useful in providing additional information about stroke risk in people with high blood pressure," Ikram said.