Branch retinal vein occlusion (BRVO) is an eye condition where a small vein in the retina becomes blocked. This blockage often leads to macular edema, which is swelling in the macula, the part of the eye responsible for sharp central vision. This swelling can significantly impair sight and requires prompt medical attention.
What is Branch Retinal Vein Occlusion with Macular Edema?
The retina, a light-sensitive tissue at the back of the eye, converts light into electrical signals for vision. Retinal veins drain blood from the retina, ensuring proper blood flow and nutrient exchange.
During a branch retinal vein occlusion, one of these smaller veins becomes obstructed. This blockage can occur where a retinal artery crosses over a vein, compressing it and leading to turbulent blood flow and clot formation. The superotemporal quadrant is most commonly affected, occurring in approximately 63% of cases.
When a branch vein is blocked, blood and fluid leak into the surrounding retinal tissue. This leakage often accumulates in the macula, the central part of the retina responsible for detailed, sharp vision.
Fluid accumulation in the macula results in macular edema, the primary cause of vision loss in BRVO. Reduced blood flow also triggers inflammatory substances and vascular endothelial growth factor (VEGF). These factors increase blood vessel permeability, contributing to swelling and fluid leakage.
Identifying the Symptoms and Causes
Symptoms of branch retinal vein occlusion with macular edema appear suddenly and affect one eye. Common signs include blurred or distorted central vision, which can worsen over hours or days. Individuals may also notice dark spots or “floaters” from tiny clumps of blood leaking into the vitreous.
A partial or complete loss of vision in a specific part of the visual field can also occur. While less common, some individuals might experience pain. The severity of these symptoms can vary depending on the location and extent of the vein blockage and the resulting macular edema.
Several factors increase the likelihood of developing BRVO. High blood pressure (hypertension) is a significant risk factor, as it can cause arteries to harden and compress nearby veins. Other contributing conditions include diabetes, high cholesterol, and glaucoma, which can all damage blood vessels over time.
Certain blood clotting disorders can also increase the risk of a blockage. BRVO is more common in individuals over 50.
Diagnosis and Treatment Options
Diagnosing branch retinal vein occlusion with macular edema involves a comprehensive eye examination. An ophthalmologist will dilate the pupils to get a clear view of the retina. The examination may reveal retinal hemorrhage, thickened and twisted blood vessels, and swelling.
Optical Coherence Tomography (OCT) provides detailed cross-sectional images of the retina, allowing doctors to detect and measure macular edema. Fluorescein angiography is another diagnostic tool where a special dye is injected into an arm vein.
As the dye travels through retinal blood vessels, a specialized camera captures images, highlighting areas of leakage or inadequate blood flow. Blood tests may also be conducted to check for underlying systemic conditions like high blood pressure or diabetes.
Treatment for BRVO with macular edema primarily aims to reduce swelling and improve vision. Anti-VEGF (vascular endothelial growth factor) injections are often the first-line treatment. These medications, such as ranibizumab (Lucentis), aflibercept (Eylea), and bevacizumab (Avastin), block the action of VEGF, a protein that promotes abnormal blood vessel growth and leakage.
These drugs are administered directly into the eye through a fine needle, typically requiring regular injections to maintain their effect. Steroid injections or implants, like the dexamethasone implant (Ozurdex), are another treatment option. Corticosteroids work by reducing inflammation and swelling in the retina.
Laser photocoagulation uses a laser to make small burns around the macula to seal leaking blood vessels. Laser treatment is still used to address specific areas of poor blood flow or abnormal new vessel growth.
Prognosis and Management
With timely and appropriate treatment, many individuals with branch retinal vein occlusion and macular edema experience significant improvement in their vision. Factors like the initial severity of the occlusion, the duration of the macular edema, and the presence of underlying health conditions can influence the long-term visual outcome. While vision often improves, some individuals may still have some persistent visual impairment.
The condition can recur, emphasizing the ongoing need for careful monitoring. Regular follow-up appointments with an ophthalmologist are important to track the condition, assess treatment effectiveness, and make adjustments as needed. These appointments help detect any recurrence of macular edema or development of new complications.
Managing systemic health conditions is a part of long-term care and helps prevent future events. This includes controlling blood pressure, diabetes, and cholesterol levels, along with lifestyle modifications like a balanced diet and regular exercise. This comprehensive approach supports better long-term outcomes and reduces the risk of future vascular events in the eye.