A measurement of ocular pulse amplitude (OPA) may help eye care providers identify patients who are at an increased risk for stroke, according to a study in the June issue of Ophthalmology. The researchers suggest that OPA can reliably detect carotid artery stenosis (CAS), a condition that clogs or blocks the arteries that feed the frontal portion of the brain.
A measurement of OPA is calculated by determining the difference between the systolic and diastolic blood pressures within the eye. When ocular blood flow is slowed or partially obscured by CAS, there is little difference between the pressure levels—resulting in a low OPA score.
In this study, researchers used a dynamic contour tonometer to document the OPA of 67 patients with presumed CAS. At its conclusion, the researchers determined that patients with the lowest OPA scores exhibited the most acutely blocked arteries. They subsequently performed an ultrasound on each patient to corroborate the OPA testing results and determine the severity of the blockages.
“Our results show that ocular pulse amplitude is a reliable, safe screening test for carotid artery stenosis,” said lead author Pascal B. Knecht, M.D., senior researcher at the University of Zurich Eye Clinic. “We recommend further study to confirm the value of using OPA to detect and assess the severity of CAS and to define its use in stroke prevention.”
The researchers further suggested that, other than CAS, very few conditions could cause low OPA scores. Therefore, by taking a measurement of OPA, they believe that eye-care providers could efficiently determine which patients are at the greatest risk for stroke and easily rule out the presence of other diseases during a standard ocular examination.
Knecht PB, Menghini M, Bachmann LM, et al. The ocular pulse amplitude as a noninvasive parameter for carotid artery stenosis screening: a test accuracy study. Ophthalmology. 2012 Jun;119(6):1244-9.