Damage to Optic Nerve in Glaucoma Patients May Indicate Carotid Artery Narrowing
Glaucoma is often associated with elevated pressure inside the eye (intraocular pressure, or IOP) which can damage the optic nerve, leading to vision loss and even blindness. Medication and/or surgery allow patients to control their IOP, thus preventing the development of vision loss. Mostafa Elgohary, MD, of Essex County and Broomfield Hospitals in the UK and his colleagues were concerned when several patients who had been under their care for several years continued to lose their vision in one or both eyes even though their IOP had been kept within normal limits either through medicine or surgery.
The authors reviewed 16 retrospective case reports to determine if there was a possible association of internal carotid artery narrowing, or stenosis, with the development of glaucoma or glaucoma-like damage to the optic nerve. The internal carotid arteries are the main arteries in the neck that carry the blood to the brain and the eye.
On further investigation, the authors found that six of those patients had significant carotid artery narrowing (greater than 60 percent of the artery lumen) and some even had total blockage of the artery on the same side as the eye with the glaucoma, or on both sides. One patient showed improvement in the visual field after undergoing surgery to remove the blockage.
The authors then extended their investigation by prospectively collecting data for 58 patients who were referred with similar optic nerve or visual field changes and carotid artery stenosis as part of the hospital audit system and found that 17 percent of these patients had significant carotid artery narrowing.
The study results are significant because they add to the evidence for the role of reduced blood flow to the optic nerve as a possible cause or predisposing factor for glaucoma or glaucoma-like optic nerve damage. Moreover, the results indicate a possible association with significant carotid artery narrowing which is a potentially serious condition as it carries the risk of stroke.
"The study is of a small scale and will obviously need further research to confirm the findings," the authors say. "However, in the meantime it may be prudent to consider referring patients with progressive or asymmetric glaucoma despite normal eye pressure - especially in the presence of cardiovascular risk factors such as hypertension, hypercholesterolemia or ischemia heart disease - for carotid artery Doppler scan to pick up those who could be at high risk for stroke and may benefit from carotid artery treatment."