The eyes rely on the free flow of blood to operate correctly. When this flow is interrupted it can lead to retinal damage and other complications that can put an individual at increased risk of vision loss. This includes things like eye strokes and occlusions in the arteries or veins of the eye.
What Is An Eye Stroke?
An eye stroke is typically associated with a blockage in an artery or vein that supply the eyes with blood. In some of these cases, the interruption of blood flow to the eyes can cause vision loss and other eye-health complications. This is especially concerning if the eye stroke cuts off blood flow to vital structures like the retina or optic nerve.
An eye stroke is associated with a lot of the same risk factors as a stroke that occurs in the brain. This includes things like high blood pressure, artery disease, or other forms of heart disease. In some cases, the risk of an eye stroke can be detected during a comprehensive eye exam.
It’s also worth bearing in mind that there are different types of eye strokes known as central retinal artery occlusion and central retinal vein occlusion.
What Is Central Retinal Artery Occlusion?
Sometimes referred to as CRAO, central retinal artery occlusion typically occurs with sudden, and significant vision loss in one eye with little to no pain. Many CRAO sufferers can barely see their hand in front of their face or perceive light in the affected eye.
A central retinal artery occlusion is sometimes preceded by episodes of vision loss known as amaurosis fugax. Most CRAO events are the result of a clot or embolus that travels from the neck via the carotid artery and essentially blocks critical blood flow to the retina in the back of the eye.
Roughly two-thirds of patients who experience a CRAO have underlying high blood pressure issues and a quarter of those individuals have significant carotid artery disease which causes arterial plaque to narrow the blood vessel walls.
Fortunately, an ophthalmologist might be able to diagnose CRAO after an examination of the eye as part of a dilated pupil exam. With most CRAOs the retina will be pale and the blood vessels will be narrow. Though sometimes a fluorescein angiogram may be needed to diagnose the CRAO, where an injection of fluorescein is intravenously administered followed by retinal photography.
CRAO is difficult to treat. Though in some cases an ophthalmologist might be able to dislodge the embolus using special glaucoma medications to decrease internal pressure in the eye. This might also be done in conjunction with an ocular massage while inhaling a solution of 5% carbon dioxide gas.
In some cases, a surgical procedure known as an anterior chamber paracentesis can be performed. This involves applying numbing drops before a small amount of fluid is withdrawn from the front of the affected eye.
If the blood flow is restored to the eye in a reasonably short amount of time, the retina’s function might be partially restored. Though most people who suffer a CRAO with retina damage suffer irreversible loss of vision after 90 minutes.
Some CRAO sufferers will also have temporal arteritis, which is sometimes called giant cell arteritis. This is an inflammatory condition that affects the arteries and might be treated with systemic steroids to prevent loss of vision to both eyes.
Central Retinal Vein Occlusion
Also known as CRVO, central retinal vein occlusion causes sudden, yet painless vision loss that can vary in severity. Many CRVO sufferers have unregulated high blood pressure, or chronic open-angle glaucoma with a significant hardening of the arteries.
African Americans and males over the age of 55, have a higher risk for CRVO and CRVO complications that can lead to vision loss. Individuals with blood clotting disorders who are not specifically taking blood thinner medications are also at heightened risk of suffering a central retinal vein occlusion. It’s also worth noting that people with diabetes and end-organ damage, such as diabetic retinopathy, are at increased risk of suffering a CRVO.
When CRVO occurs, a thrombus or clot develops in the central retinal vein just where blood flow enters the eye. Many times the treating physician will find mild to severe hemorrhages and cotton-wool spots in the retina as a result.
CRVOs can be broken down into two categories. An ischemic CRVO is related to poor blood flow and accompanying poor vision. In a non-ischemic CRVO, the end result is a much better vision when you are first seen.
With both an ischemic CRVO and non-ischemic CRVO treatment often involves using a laser in a pan-retinal photocoagulation treatment in attempts to cause regression of the neovascularization in the retina. Neovascularization is a type of vision-impairing hemorrhage that can cause significant scar tissue and even the potential separation of the retina from the back of the eye.
In some CRVO cases, ocular massage or glaucoma medications might be able to lower eye pressure. This might be administered as part of the retinal photocoagulation treatment process.
Initial vision loss in a CRVO event is a good indicator of the final visual outcome. In general, the more severe the initial vision the worse the final visual acuity will be after treatment. Roughly 50% of people who experience a CRVO, final visual acuity remains is limited to three lines on an eye chart.
How To Reduce The Risk Of Suffering An Eye Stroke?
Diabetics are particularly at high risk for suffering a CRAO or CRVO eye stroke. If you have recently been diagnosed with diabetes or borderline diabetes, it’s important to closely monitor your blood sugar with a glucometer. Exercise and improvements in your diet will also help reduce the risk of suffering an eye stroke.
Individuals with glaucoma are also at increased risk of suffering a CRAO or CRVO eye stroke. If you have glaucoma you need to follow your eye doctor’s recommended treatment plan closely. An annual eye exam is also a good idea to catch any possible complications in the early stages.
It’s also worth bearing in mind that a lot of the things you would do to reduce heart disease and stroke risk will also reduce your risk of suffering a CRAO or CRVO eye stroke. This includes seeking treatment for high blood pressure, checking your cholesterol and keeping it in a healthy range, and quitting smoking.