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Ocular ischemic syndrome occurs when atherosclerotic plaques affect the blood vessels that provide blood to the eyes. (Learn More) Treatment usually requires a multidisciplinary approach.
Treatments may include carotid surgery or blood thinners followed by intravitreal injections or panretinal photocoagulation. (Learn More)
Ocular ischemic syndrome is a rare condition that affects about 5 percent of people who have carotid artery obstruction. In the United States, approximately 2,100 patients experience this syndrome every year. It is typically observed in people ages 65 and older. The ratio of men to women who experience this syndrome is 2:1.
People can experience pain and vision loss with this condition. (Learn More) Amaurosis fugax is another symptom that occurs in the form of a transient episode.
Diagnosis involves examining the eyes and looking for signs of carotid artery disease via a cardiovascular examination. (Learn More)
After making an accurate diagnosis, the doctor can determine if medications or surgery should be the first step. From here, photocoagulation or injections might be considered. (Learn More)
What Is Ocular Ischemic Syndrome?
Ocular ischemic syndrome occurs when the eyes are not getting adequate blood. This can result from carotid artery disease. Among people ages 65 and older, about 3 percent have carotid artery disease.
Carotid artery disease is characterized by the blood vessels getting at least partially obstructed by fatty deposits. This results in reduced blood flow to the brain and other areas served by the carotid arteries.
The carotid arteries are located in the neck, and they are the primary arteries sending blood to the brain. As people get older, plaque starts building up in the arteries.
If the carotid arteries are affected, this can result in stenosis, or narrowing of these arteries. This can reduce blood flow and cause small clots to form and break off.
Ocular ischemic syndrome can be a complication of carotid artery disease. When people have this condition, 90 percent or more of a stenosis of the internal carotid arteries is typically observed. This is on the same side.
It is estimated that the stenosis decreases the perfusion pressure by about 50 percent in the central retinal artery. This condition typically develops in people who have poor collateral circulation between their two internal carotid arteries or between the external and internal carotid arteries.
The primary cause of ocular ischemic syndrome is atherosclerosis. Other causes include:
- Dissecting aneurysm. An aneurysm is a bulge that happens in an artery. When a dissection occurs, the layers of the vessel can tear or separate. Over time, this may cause the affected area to burst.
- Fibrovascular dysplasia. The cells in the arterial walls may develop abnormally, which can result in the vessel bulging or narrowing.
- Aortic arch syndrome. This syndrome is characterized by different structural issues affecting the arteries that connect to the aortic arch.
- Giant cell arteritis. This condition can cause the temporal artery to thicken and swell.
- Takayasu arteritis. This condition is rare, and it is unknown what causes it. It is characterized by inflammation of the large blood vessels.
Approximately 90 percent of people with ocular ischemic syndrome experience vision loss in the eye that the condition affects. This is typically due to acute or chronic retinal ischemia or optic nerve damage associated with secondary glaucoma.
In about 12 percent of people, vision loss can occur suddenly. However, it usually happens over days or months.
Issues with visual acuity can occur. In the later stages of this syndrome, neovascular glaucoma may occur and cause a loss of light perception.
Neovascular glaucoma is characterized by the eye’s angle closing as a result of new blood vessels. The ischemia of ocular ischemic syndrome affects the retina and results in this eye structure not getting enough oxygen due to reduced blood flow. As a result, the retina tries to counteract the ischemia by releasing chemicals, including vascular endothelial growth factor (VEGF).
The formation of new blood vessels is due to VEGF. Instead of these new blood vessels bringing more blood to the retina, they are abnormal and leaky. This can result in redness, pain, and reduced vision.
Making the Diagnosis
The diagnostic process usually involves both a cardiovascular exam and an ophthalmic exam. During the cardiovascular exam, the doctor performs carotid and cardiac auscultation and checks the pulses in the arm.
The ophthalmic exam is more extensive. The doctor dilates the eyes, so they can get a better view of the different structures. The doctor can usually see the retinal veins irregularly dilated while the retinal arteries are narrowed.
Certain blood tests might be performed if the doctor suspects specific causes of this condition. For example, if giant cell arteritis is believed to be present, they may order a C-reactive protein or erythrocyte sedimentation test. These are both blood tests.
Certain imaging studies may be helpful to make the diagnosis, such as:
- Fluorescein angiography. If someone has ocular ischemic syndrome, this test may show prolonged arm-to-retina or arm-to-choroid circulation times, choroidal filling, retinal vessel staining, patchy or delayed, higher retinal arteriovenous transit time, and retinal capillary nonperfusion.
- Magnetic resonance imaging. This test allows the doctor to see the anatomical details of the vessels in greater detail.
- Color doppler imaging. This test allows the doctor to look at the blood flow in the ophthalmic artery to determine if it is increased or decreased.
- Carotid angiography. This test may be performed to determine a person’s risk for stroke.
If additional testing is necessary, doctors may recommend:
- This test may be performed if the doctor cannot exclude an occlusion of the central retinal vein. The doctor is looking for normal or increased pressure to indicate an occlusion of the central retinal vein. The pressure of the ophthalmic artery is low if someone has carotid disease.
- If someone has ocular ischemic syndrome, this test will show an absence or decrease in B-waves and A-waves.
In severe cases, doctors may perform carotid endarterectomy. This procedure works to restore normal blood flow.
If an ultrasound showed blockages in the carotid arteries, doctors may perform this surgery as a diagnostic test. When used as a treatment, it is not a cure. The plaques can accumulate in the carotid arteries again without other measures to treat high cholesterol or another underlying problem.
During the surgery, people receive general anesthesia so they are asleep, or they get local anesthesia to numb the area that the doctor is working on. The blocked carotid is exposed, and the plaque is removed.
In less severe cases, blood-thinning medications may be sufficient to alleviate the blockage. Doctors prescribe these medications to stop existing clots from growing or to prevent a clot from developing at all.
These drugs work in two ways, depending on the exact medication the doctor prescribes.
- Some prevent blood cells from being able to stick together.
- Some increase how long it takes for a clot to develop.
After carotid surgery, additional procedures may be performed if the retina or iris have new blood vessel growth. These procedures include:
- Intravitreal injections. The doctor injects medicine into the eye near the retina. This is done if there is an occlusion in the central retinal vein. It takes about 30 minutes or less to complete this procedure, and it is done in the doctor’s office.
- Panretinal photocoagulation. This procedure may be performed if proliferative diabetic retinopathy is also present. It uses a special laser that seals the retina, so new blood vessels stop growing. It helps to reduce the risk of retinal detachment and vitreous hemorrhage. Once the right areas are treated, abnormal blood vessels that are already present usually disappear or decrease.
If ocular ischemic syndrome is suspected, it is important to see a doctor right away. In the early stages, surgery might not be necessary, but if the condition is allowed to continue, treatment can become more invasive.
With prompt and proper treatment, people have options. The artery is completely obstructed in about 50 percent of cases.
Detecting the Ocular Ischemic Syndrome. American Academy of Ophthalmology.
Carotid Artery Disease. Society for Vascular Surgery.
The Ocular Ischemic Syndrome. Clinical, Fluorescein Angiographic and Carotid Angiographic Features. International Ophthalmology.
Ocular Ischemic Syndrome - A Systematic Overview. Medical Science Monitor.
The Ocular Ischemic Syndrome. Visual Prognosis and the Effect of Treatment. International Ophthalmology.
Ocular Ischemic Syndrome. Survey of Ophthalmology.
Carotid Endarterectomy. National Heart, Lung, and Blood Institute.