Simple Eye Test May Assess Stroke Risk

Carotid artery stenosis (CAS) is a condition that clogs or blocks the arteries that feed the front part of the brain, and is considered a risk factor for stroke.  Pascal B. Knecht, from the University Hospital Zurich (Switzerland), and colleagues report that an ophthalmological test called ocular pulse amplitude (OPA) can reliably detect CAS. The researchers used a device called the dynamic contour tonometer to check the OPA of 67 patients who were assumed to have CAS. The OPA score is calculated by finding the difference between the two pressure levels that occur inside the eye during the two phases of the heartbeat − the systolic and diastolic. The tonometer measures the two pressure levels, then instantly computes the patient’s OPA score. When blood flow to the eye is blocked by CAS, there is not much difference between the two pressure levels, so the OPA score is low. The study confirmed that patients with the lowest OPA scores also had the most seriously blocked arteries. The researchers used ultrasound exams to corroborate that each study participant had CAS and to detail the severity of his or her blockage. The study authors conclude that: “The results of the present study provide proof of principle that the [ocular pulse amplitude] is reduced in patients with [carotid artery stenosis] and may be used as a noninvasive, inexpensive, readily available, and unconfounded screening parameter to detect [carotid artery stenosis] and possibly to reduce the incidence of stroke.”