Oculoplethysmography (OPG)

Carotid patency evaluation and ocular pneumoplethysmography.

To detect narrowing or blockage of the carotid arteries that run on both sides of the neck. Their narrowing can interrupt blood supply to the brain and cause transient ischemic attacks or stroke.

It provides an indirect measurement of blood flow in the opthalmic artery, which reflects the blood flow to the brain through the carotid arteries.

You remove contact lenses if you wear them, and anesthetic eyedrops are placed into your eyes.

• Eye pressure is measured through small suction cups placed over the eyes.
• Eyecups that look like contact lenses are attached to the corneas of the eyes, and probes are attached to the earlobes. Both have sensors that allow them to detect the pulse rates in the vessels supplying the eyes and ears.
• As a vacuum is applied to the eyecups, they may be used to measure the blood pressure in the eye artery.

• You are free to resume normal activities.
• Avoid rubbing your eyes for 30 minutes.
• After 30 minutes, you can reinsert your contact lenses.
• You may experience blurred vision for a short while.

• Blinking and eye movements.
• High blood pressure.
• Abnormal heart rhythm.

The pulse rates in the eye and earlobe are compared. Normally, the pulse should occur simultaneously in the two locations. If there is a delay between the pulses, a carotid artery may be narrowed or blocked.

It's quick and noninvasive.

• It detects only severe narrowing or blockage.
• Other tests (ultrasound or angiography) are required to confirm the diagnosis and have largely replaced this technique.

Angiography.