Ocular ischemic syndrome (OIS) is a rare eye condition resulting from a significant reduction in blood flow to the eye. This decrease in blood supply means the various structures within the eye, which rely on a steady delivery of oxygen and nutrients, do not receive what they need. The condition can affect both the front and back parts of the eye, impacting its overall function. It can lead to vision problems and other ocular issues.
Underlying Causes and Risk Factors
Ocular ischemic syndrome often signals an underlying systemic vascular condition. The most common cause is severe carotid artery disease, where plaque builds up in the carotid arteries located in the neck. These arteries are responsible for supplying blood to the head and eyes, and significant narrowing, often 90% or more, can severely restrict this flow.
Several other factors contribute to the development of OIS, primarily those linked to widespread atherosclerosis, a condition where arteries harden and narrow due to plaque buildup throughout the body. Advanced age is a common factor, with the condition typically affecting individuals between 50 and 80 years old, and men are affected about twice as often as women. Other significant risk factors include diabetes mellitus, high blood pressure (hypertension), and a history of smoking. Heart disease and previous strokes or transient ischemic attacks also increase a person’s susceptibility to OIS.
Recognizable Signs and Symptoms
Patients with ocular ischemic syndrome often experience a gradual decline in vision, typically affecting one eye over weeks or months. This differentiates it from the sudden vision loss seen in some other eye conditions.
A distinct symptom is “ocular angina,” a dull, aching pain in or around the affected eye that may spread to the eyebrow. This pain often worsens when a person is upright and may improve when lying down. Another indicator can be prolonged recovery of vision after exposure to bright light, which occurs because the light-sensing cells in the eye take longer to recover due to reduced blood flow. Some individuals may also notice floaters in their vision, which are small specks or cobwebs that drift across the field of view.
The Diagnostic Process
Confirming a diagnosis of ocular ischemic syndrome involves a thorough eye examination combined with specialized imaging tests. An ophthalmologist will carefully examine the eye’s internal structures, looking for specific signs of reduced blood flow. These signs can include narrowed retinal arteries and dilated retinal veins. The doctor also checks for neovascularization, which is the growth of new, abnormal blood vessels, often on the iris or retina, in response to low oxygen levels.
To visualize the blood flow in the eye, doctors may perform fluorescein angiography, a procedure where a dye is injected into a vein, and special cameras capture its movement through the retinal blood vessels. This test can reveal delayed filling of blood vessels or areas of non-perfusion. To identify the root cause of the reduced blood flow, a carotid artery ultrasound, also known as Doppler imaging, is commonly performed. This non-invasive test uses sound waves to create images of the carotid arteries in the neck, helping to detect blockages or narrowing that restrict blood flow to the head and eyes.
Medical Management and Treatment Approaches
Treatment for ocular ischemic syndrome has two primary aims: addressing the eye-specific issues and managing the underlying systemic cause of reduced blood flow. For the eye, one common approach is pan-retinal photocoagulation, a laser procedure that selectively treats areas of the retina. This laser treatment reduces the retina’s overall oxygen demand, helping to prevent the growth of abnormal blood vessels and stabilize the eye.
Another eye treatment involves anti-VEGF injections, which are medications injected directly into the eye to control the growth of new, fragile blood vessels and reduce swelling. Addressing the systemic cause, particularly the carotid artery blockage, is a paramount step. This may involve procedures such as carotid endarterectomy, a surgical procedure where plaque is physically removed from inside the carotid artery, or carotid artery stenting, where a small mesh tube is placed to hold the artery open and improve blood flow. Collaboration between an ophthalmologist and a vascular or primary care physician is needed to manage both eye and systemic conditions.
Associated Health Implications
Ocular ischemic syndrome signals widespread cardiovascular disease. The carotid artery blockages causing OIS indicate a higher risk for other life-threatening events. Individuals with OIS face an elevated risk of experiencing a stroke or a heart attack.
About 40% of patients diagnosed with OIS may die from a heart attack or stroke within five years of diagnosis. This underscores the broader importance of managing overall health, beyond just eye health. Controlling blood pressure, managing diabetes, and lowering cholesterol levels are all part of a comprehensive strategy to reduce the risk of future cardiovascular events and improve long-term survival.