Retinal Vein Occlusions & Artery Occlusions
As with other eye structures, your retina, an ultrathin nerve layer found on the back eyewall, must be continuously nourished with oxygen-rich blood. While the buildup of fatty deposits or blood clots is never beneficial, within the retina’s blood vessels, these are especially harmful. You may then be at risk for retinal artery or vein occlusions, The resulting blockages can prevent this crucial oxygen and blood from arriving at its destination, the retina. You can then go through unpleasant symptoms, like swelling, and as eye inflammation and swelling, and as time progresses, fragile, abnormal new blood vessels may sprout, with permanent vision loss a possibility.
Considered a leading cause of acute vision loss, 1 to 2 cases of retinal artery occlusions (RAO) are found for every 100,000 people per year. As for retinal vein occlusions (RVO), they’re very common, shown to afflict more than 16 million people. While RAOs and RVOs are incurable, their underlying conditions and risk factors can be managed. If treatment is needed, injectable medications and laser therapy may seal leaking blood vessels and break down blood vessel damage. While these conditions are considered medical emergencies, immediate treatment may enable you to preserve some vision. At Retina Consultants of Charleston, we’re experienced in treating retinal artery occlusions and retinal vein occlusions.
Retinal Artery and Vein Occlusion Development
Your circulatory system continuously performs an intricate process, with one type of blood vessel, arteries, transporting blood from the heart and distributing it throughout the body. At the same time, blood vessels called veins return all of the tissues’ blood, and related waste materials, to the heart. Oxygenated blood is delivered by the retinal vascular system. The primary components are the central retinal vein and the central retinal artery, extending from the neck’s internal carotid artery. These vessels extend from the optic nerve, getting closer together, reducing in size, and speeding up as they approach the retina.
With hypertension (high blood pressure), over time, your arterial walls slowly get thicker and become more solid. This causes neighboring veins to condense, with blood flow delaying and stopping. You may then experience breaks in your smallest and most abundant blood vessels, the capillaries. This pressure accumulates, culminating in inflammation and retinal bleeding.
If you have significant retinal leakage, this can cause swelling in the macula, the center of the retina. Known as macular edema, this condition may be serious, as the macula controls your sharp, straight-ahead vision, enabling close-up activities like reading and driving. As blood loss within the retina gets worse, irregular blood vessels may grow, and permanent vision loss may develop.
Familiarizing Yourself With Different Retinal Occlusion Types
There are various types of retinal artery and vein occlusions, dependent on the specific artery or vein affected and its placement within the retina.
A branch retinal artery occlusion (BRAO) is the result of blood clots developing in a branch stemming from the central retinal artery. Should oxygen-rich blood fail to reach the macula, the retina’s center, you may experience a loss of central vision, enabling “close-up” activities, like reading. Research suggests that the incidence of BRAO is about 30% of CRAO.
Referred to as “eye stroke,” a central retinal artery occlusion (CRAO) is a critical condition. While its main symptom is sudden, painless vision loss, there may be blind spots, distorted vision, and peripheral (side) loss of vision. The development of CRAOs can impede retinal blood flow, leading to severe vision loss. CRAO incidence is about 1 to 2 in 100,000, and men, specifically those averaging 60-65 years, are more likely to be afflicted.
A BRVO is a blockage in a smaller retinal vein. Generally, if they occur outside of the eye's center, they cause painless, sudden vision loss. They can cause blood and other fluids to leak into the retina. While BRVOs may have no symptoms, you may experience eye floaters, loss of peripheral vision, and distorted or blurry central vision. You may also have bleeding in the vitreous, the clear, jelly-like gel that makes up most of the eye’s volume.
Should a blockage develop in the main retinal vein, this is known as a central retinal vein occlusion (CRVO). A serious condition, CRVOs can cause structural damage to the veins, leading to retinal bleeding and fluid leakage. To compensate, your eyes develop new, fragile veins, but they’re prone to bleeding and leaking and may cause floaters.
CRVOs target 1-4 in 1,000 people, while branch retinal vein occlusions (BRVOs) develop in 6-12 in 1,000 people.
What Are Typical Retinal Artery Occlusion Symptoms?
Sudden, painless vision loss is the most common RAO symptom. CRAO leads to the complete loss of vision in one eye, while BRAO affects only part of one eye. It is possible that vision lost in the past may return, due to blood clots. Other symptoms include the sudden appearance of:
- Complete vision loss
- Loss of side (peripheral) vision
- Distorted vision, in which things may look wavy or out of shape
- Blind spots in your vision
Any of these symptoms are considered an emergency, requiring immediate medical attention, as this will prevent the development of a brain stroke.
What Are Typical Retinal Vein Occlusion Symptoms?
RVO generally targets a single eye, with symptoms including:
- Blurry vision or vision loss, which may start suddenly or develop gradually over hours or days.
- Eye floaters, which are dark spots or lines in your field of vision.
- Pain or pressure in your eye, which is generally seen in more severe cases.
With RVO, symptoms may not manifest until complications develop. Patients may not be aware that they have an issue until their ophthalmologist identifies it during a routine eye exam.
Are Retinal Occlusions Considered Medical Emergencies?
A significant risk of BRAO and CRAO is that they may signal higher risks for cerebral stroke development. If not treated in under 24 hours, CRAO can give rise to permanent vision loss. With earlier CRAO treatment, the likelier your chances of keeping some vision. CRAOs are also considered medical emergencies.
Risk Factors For Artery And Vein Occlusions
Studies show that for retinal artery and vein occlusions, patients are typically in their 60s, and men tend to develop them more than women. Assuming blood flow is restored, occlusions usually last for only a few seconds or minutes. In most cases, occlusions target a single eye, with both eyes being affected in only 1-2% of cases. Among the common risk factors are:
- Aging
- Smoking
- Being overweight or obese; having an increased body mass index (BMI)
- Cardiovascular disease
- Diabetes
- High blood pressure, especially among senior patients
- High cholesterol
- Narrowing of the carotid artery
- Glaucoma
- For younger BRVO patients, there may be an abnormal blood clotting tendency
- Female CRAO patients may have blood that is thicker and stickier than normal; this may be associated with birth control pill use.
Diagnosis of Retinal Vascular Occlusions
If you suspect a retinal occlusion, your retina specialist will conduct a thorough eye exam. The exam’s purpose is to assess your eye’s health and function, and it will include the doctor checking your vision, measuring your eye pressure, and taking your blood pressure.
For mild artery or vein occlusions, the retinal specialist will usually just monitor your eyes. You can expect your eyes to be dilated, which involves special eye drops being applied to keep the pupil open, allowing a closer, unobstructed look at your retina. In addition, there may be such diagnostic tests as:
The test known as an ophthalmoscopy involves a retinal specialist employing an ophthalmoscope, an instrument enabling retinal damage to be observed and evaluated. If you are afflicted with diabetes, you are advised to have this test at least once per year.
With this diagnostic test, involving highlighting the eye’s blood vessels, the retinal specialist injects a colored dye into the bloodstream. They then take photographs and analyze these images for signs of closed, broken, or leaking blood vessels.
Optical coherence tomography (OCT) is a diagnostic test in which infrared light captures cross-sectional retinal images. The goal of OCT is to find out if any fluid has seeped into the retinal tissue.
Should you undergo indocyanine green angiography, this involves the technician injecting dye that lights up when exposed to infrared light. However, with this test, the retina’s deeper blood vessels are examined.
Retinal Artery And Vein Occlusion Treatments
Retinal artery or vein occlusions are, as of now, incurable, and typically, your ophthalmologist will advise you to follow a precise management regimen for underlying conditions and related risk factors, including cardiovascular disease and hypertension. Should treatment be recommended for a retinal occlusion, the primary goal is to close off any leaking blood vessels.
If you experience any bleeding or the formation of macular edema — swelling within the macula — anti-vascular endothelial growth factor (anti-VEGF) medications may be administered. These drugs work by helping to halt the development of unusual, fragile blood vessels by constraining the proteins at fault. Anti-VEGF medications are injected by ophthalmologists, using a very thin needle, directly into your problem eye’s vitreous. Anti-VEGF medications have been found to effectively regulate retinal vascular diseases and assist in the maintenance of healthy vision.
As you undergo this process, there may be the need for accompanying techniques, such as focal laser therapy. Your ophthalmologist may also perform a surgery, known as photocoagulation, in which a high-energy laser beam is used to reduce blood vessel damage or close off blood vessel leakage.
What Is The General Retinal Occlusion Prognosis?
In most cases, if you are diagnosed with a retinal occlusion, you can expect to do well. If macular edema is the only condition present, you’ll probably require injections, which will need to be continued for several years, until the impaired blood vessels restore themselves. Should macular blood vessel loss manifest, permanent vision loss is a potential risk.
Learn More About Retinal Artery and Vein Occlusions
Retinal artery occlusions and retinal vein occlusions can cause extensive damage to your eyes. However, the vitreoretinal surgeons of Retina Consultants of Charleston are experienced in treating these conditions. If you suspect an occlusion or have general retinal questions, please contact our retinal specialists for an appointment.
