Central Retinal Vein Occlusion (CRVO) occurs when the main vein responsible for draining blood from the retina, the light-sensitive tissue at the back of the eye, becomes blocked. This blockage can be likened to a “stroke in the eye,” causing blood and fluid to leak into the retina. The leakage often leads to swelling of the macula, the central part of the retina responsible for sharp, detailed vision, which in turn can cause blurry vision or sudden vision loss. Various treatments are available to manage its effects and help stabilize or improve vision. The primary goal of these interventions is to address the complications arising from the blocked vein, helping to preserve retinal function.
Intravitreal Injections
Intravitreal injections involve delivering medication directly into the vitreous humor, the clear, gel-like substance that fills the center of the eye. These injections are a common first-line treatment for CRVO, especially when vision loss is due to macular edema.
Two main types of medications are used for intravitreal injections: anti-VEGF drugs and corticosteroids. Anti-VEGF (anti-vascular endothelial growth factor) medications target a protein called VEGF, which contributes to abnormal blood vessel growth and increased fluid leakage in the eye. Common anti-VEGF drugs include ranibizumab (Lucentis), aflibercept (Eylea), and bevacizumab (Avastin), with ranibizumab and aflibercept being FDA-approved for CRVO-related macular edema. Bevacizumab is widely used off-label in ophthalmology.
Corticosteroids are another class of drugs injected to reduce retinal swelling by suppressing inflammation. Dexamethasone intravitreal implant (Ozurdex) is a sustained-release corticosteroid often used for macular edema following CRVO. This implant slowly releases dexamethasone over time, targeting various inflammatory pathways, decreasing VEGF expression, and stabilizing vessel permeability to reduce fluid buildup.
The injection procedure is typically quick and performed in an office setting. Before the injection, numbing drops are applied to the eye. The area around the eye is then cleaned, and a speculum may be used to keep the eyelids open. The medication is injected with a very fine needle into the vitreous.
Laser Therapy Procedures
Laser therapy for CRVO is distinct from injections and is generally employed to manage specific complications that can develop later in the disease course, rather than addressing the initial macular swelling. The main objective of laser treatment is to prevent or treat neovascularization, which is the growth of new, abnormal blood vessels on the retina or iris. These new vessels are prone to bleeding, leading to vitreous hemorrhage, or can cause a severe form of glaucoma known as neovascular glaucoma.
Pan-retinal photocoagulation (PRP) is the most common laser procedure for CRVO complications. This treatment involves making numerous tiny laser burns in the peripheral areas of the retina, away from the central macula. The laser creates small scars that reduce the retina’s oxygen demand. This reduction in oxygen demand helps to decrease the production of VEGF, thereby signaling the eye to stop growing harmful new blood vessels.
During the PRP procedure, the ophthalmologist uses a specialized laser to deliver controlled bursts of light. The patient’s eye is numbed with drops, and a contact lens is often placed on the eye to help focus the laser. The procedure typically takes between 10 to 15 minutes, and multiple sessions may be required. The laser carefully avoids the macula to preserve central vision.
Addressing Systemic Risk Factors
Understanding and managing systemic health conditions is an important part of the overall treatment approach for CRVO. A central retinal vein occlusion often indicates an underlying health issue affecting the body’s circulatory system, which can contribute to the blockage of the retinal vein.
Common systemic risk factors linked to CRVO include high blood pressure (hypertension), diabetes, high cholesterol (hyperlipidemia), and certain blood clotting disorders. For instance, high blood pressure can stiffen artery walls, potentially compressing the retinal vein where arteries and veins cross, leading to clot formation. Diabetes can also damage blood vessels, making them more susceptible to blockages. Blood disorders that increase the blood’s tendency to clot can also elevate the risk.
Working closely with a primary care physician to control these conditions is a significant part of managing CRVO. Effective management of blood pressure, blood sugar levels, and cholesterol can help reduce the risk of a second CRVO event in the other eye. This comprehensive approach addresses the root causes contributing to CRVO.
Surgical Interventions
Surgical intervention for CRVO is generally considered when other treatments have not resolved severe complications. The main complications that may necessitate surgery include persistent, non-clearing vitreous hemorrhage or retinal detachment caused by scarring.
Vitreous hemorrhage occurs when blood leaks into the vitreous humor, obscuring vision. If this blood does not clear on its own, a surgical procedure called a vitrectomy may be performed, which involves the removal of the blood-filled vitreous gel from the eye.
During the vitrectomy, tiny incisions are made in the eye, and specialized instruments are used to remove the cloudy vitreous. Replacing the vitreous with a saline solution or gas helps to maintain the eye’s shape. This procedure clears the visual axis, potentially improving vision, and allows for addressing other underlying issues.