Retinal vein occlusion: treatment

The retina is a layer of nerve tissue at the back of the eye responsible for receiving light and processing images. Retinal veins drain blood from the retina back into the general circulation. A retinal vein occlusion occurs when blood flow in a retinal vein is blocked, leading to an accumulation of blood and fluid in the retina. This condition can cause hemorrhages, retinal edema (swelling), and in more severe cases, the development of abnormal new blood vessels.

Retinal vein occlusion can manifest in two main forms: Branch Retinal Vein Occlusion (BRVO), where a smaller retinal vein is blocked, or Central Retinal Vein Occlusion (CRVO), where the main vein draining the entire retina is obstructed. CRVO tends to be more severe and affects a wider area of vision.

Retinal vein occlusion is associated with several systemic risk factors that affect blood vessels. Key risk factors include hypertension, diabetes, atherosclerosis, and glaucoma. For example, hypertension can cause the walls of arteries to thicken, which then press on adjacent veins and can obstruct them. Certain blood disorders that cause increased blood clotting or thicker blood can also elevate the risk of occlusion. While retinal vein occlusion is more common in individuals over 50, it can also occur in younger people, sometimes without any known risk factors.

In cases of retinal vein occlusion in younger individuals, a more comprehensive evaluation of blood clotting status and other systemic diseases may be recommended to identify an underlying cause. Managing systemic risk factors, such as maintaining normal blood pressure and blood sugar levels, is a crucial part of preventing recurrence and reducing the risk of complications.

The primary symptom of retinal vein occlusion is a sudden decrease or blurring of vision, which is usually painless. The severity of vision loss depends on the location and extent of the occlusion. If the occlusion involves the macula (the center of vision), the impact on vision will be more significant. In more advanced stages, if abnormal new blood vessels develop, they may bleed into the vitreous cavity, causing the perception of black spots or floaters. These hemorrhages can lead to severe vision loss.

Diagnosis is made by an ophthalmologist through a comprehensive eye examination, including pupil dilation and fundus examination with a slit lamp. Advanced imaging tests such as Optical Coherence Tomography (OCT) are also used to assess retinal thickness and detect edema. Often, Fluorescein Angiography is performed, where a contrast dye is injected into an arm vein, allowing visualization of blood flow in the retinal vessels to identify areas of blockage, leakage, or lack of blood supply.

Retinal vein occlusion can lead to several significant complications. The most common complication is macular edema, which is the accumulation of fluid in the macula, causing blurred vision. Another complication is the development of abnormal new blood vessels (neovascularization) on the retina or iris surface. These new vessels are fragile and prone to bleeding into the vitreous cavity, leading to a sharp decrease in vision.

In some cases, the growth of new blood vessels can block the drainage angle of the eye's fluid, leading to an increase in intraocular pressure and secondary glaucoma (neovascular glaucoma). This type of glaucoma can cause severe pain and irreversible damage to the optic nerve, potentially resulting in complete vision loss if not treated promptly.

The goal of treating retinal vein occlusion is to reduce macular edema, prevent the growth of new blood vessels, and preserve vision. The primary treatment currently involves intravitreal injections of medications. These medications include anti VEGF agents (such as Avastin, Lucentis, Eylea) or steroids (such as Ozurdex). Anti VEGF drugs work by blocking a protein that promotes new blood vessel growth and fluid leakage, thereby reducing edema and preventing neovascularization. Steroids act by reducing inflammation and swelling. Injections are given serially, with frequency determined by the treating physician based on the eye's response and the disease's status.

Laser treatment is considered in selected cases, particularly when abnormal new blood vessels develop. PRP or laser to the affected retinal sector reduces the signals promoting these vessels and helps prevent bleeding or neovascular glaucoma. It does not reopen the blocked vein. Severe ischemia also requires close monitoring, and laser timing is individualized. Focal or grid laser may be used for macular edema in selected branch vein occlusions. If secondary glaucoma develops, treatment to lower intraocular pressure will be given, which may include eye drops or, in some cases, surgery.

After a diagnosis of retinal vein occlusion, regular follow up with an ophthalmologist is necessary. The frequency of follow up is determined by the physician based on the severity of the condition, the type of treatment, and the eye's response. Follow up is crucial to identify potential complications such as worsening edema, new hemorrhages, or the development of glaucoma. In addition to eye treatment, it is very important to manage and balance systemic risk factors, such as hypertension and diabetes, in cooperation with your family doctor or other specialists.

Seek an eye examination as soon as possible if you experience any sudden decrease or worsening of vision, the appearance of many new black spots or floaters, or eye pain. These symptoms may indicate complications requiring immediate medical intervention to prevent irreversible vision damage.