CHICAGO, April 5 (Xinhua) -- Reduced blood capillaries in the back of the eye may be a new, noninvasive way to diagnose early cognitive impairment, the precursor to Alzheimer's disease, showed a study released by Northwestern University (NU) on Friday.

NU researchers recruited 32 participants who had cognitive testing consistent with the forgetful type of cognitive impairment, and age-, gender- and race-matched them to subjects who tested as cognitively normal for their age. All individuals underwent the eye imaging with OCT angiography.

They then detected the vascular changes in the human eye non-invasively, with an infrared camera and without the need for dyes or expensive MRI scanners.

It's known that patients with Alzheimer's have decreased retinal blood flow and vessel density.

"Once our results are validated, this approach could potentially provide an additional type of biomarker to identify individuals at high risk of progressing to Alzheimer's," said Amani Fawzi, a professor of ophthalmology at NU Feinberg School of Medicine.

Therapies for Alzheimer's are more effective if they are started before extensive brain damage and cognitive decline have occurred, added Fawzi.

The researcher now hope to correlate these findings with other more standard but also more invasive types of Alzheimer's biomarkers as well as explore the longitudinal changes in the eye parameters in these subjects.

The study was published Tuesday in PLOS ONE.