Retinal vein occlusion (RVO) is a common eye condition that affects the retina, the light-sensitive tissue at the back of the eye. It occurs when a vein in the retina becomes blocked, leading to fluid leakage and blood accumulation within the retinal layers. This blockage can severely impact vision, and recent advancements in treatment offer promise for improving patient outcomes and preserving sight.
Understanding Retinal Vein Occlusion
RVO develops when a blood clot forms in one of the retinal veins, obstructing normal blood flow. This blockage causes blood and fluid to leak into the surrounding retinal tissue, leading to swelling, particularly in the macula, which is responsible for sharp central vision. The primary impact on vision includes blurred vision, distorted sight, or a sudden, noticeable loss of vision.
There are two main types of RVO: Central Retinal Vein Occlusion (CRVO) and Branch Retinal Vein Occlusion (BRVO). CRVO involves the main retinal vein, affecting a larger area of the retina and potentially leading to more widespread vision impairment. BRVO, more common than CRVO, occurs when a smaller branch vein is blocked, typically impacting a more localized area of vision. The underlying problem in both types is the compromised blood supply to the retinal cells, which can result in damage and vision loss if left unaddressed.
Primary Modern Treatments
Modern advancements in RVO treatment primarily involve anti-vascular endothelial growth factor (anti-VEGF) injections and steroid implants, which target the underlying mechanisms of vision loss. These therapies have significantly improved patient outcomes compared to older approaches. Anti-VEGF agents work by inhibiting a protein called vascular endothelial growth factor, or VEGF, which promotes abnormal blood vessel growth and increases fluid leakage in the retina. By blocking VEGF, these injections help reduce macular edema, the swelling that causes blurred vision, and can slow the progression of the disease.
Common anti-VEGF medications include ranibizumab (Lucentis), aflibercept (Eylea), and bevacizumab (Avastin). Ranibizumab and aflibercept are FDA-approved for RVO treatment, while bevacizumab is often used off-label. Clinical trials have demonstrated that ranibizumab and aflibercept significantly improve visual acuity and reduce retinal thickness in RVO patients. Faricimab (Vabysmo), approved in October 2023, also targets angiopoietin-2 (Ang-2), offering extended dosing intervals for some patients, potentially up to every four months.
Steroid implants represent another category of modern RVO treatments, designed to reduce inflammation and swelling in the retina. These implants release corticosteroids directly into the eye over an extended period. Dexamethasone intravitreal implant (Ozurdex) is a biodegradable implant that releases dexamethasone for up to six months, reducing macular edema and improving visual acuity in both BRVO and CRVO cases. Studies have shown the efficacy of dexamethasone implants in treating RVO-related macular edema.
Another steroid option is the fluocinolone acetonide (FAc) implant (Iluvien), a non-biodegradable implant capable of releasing medication for up to three years. While primarily used for diabetic macular edema, it has also been explored as an off-label treatment for chronic RVO. These implants offer a sustained therapeutic effect, potentially reducing the frequency of clinic visits and injections compared to some other treatments.
The Patient’s Treatment Journey
Receiving treatment for retinal vein occlusion involves a series of in-office procedures, primarily intravitreal injections. Before the injection, the eye is numbed with anesthetic drops to minimize discomfort. Some patients may still experience mild to moderate pain during the injection itself, although pain scores often decrease with subsequent treatments.
The injection involves a small-gauge needle inserted into the vitreous, the jelly-like substance in the eye. This allows the medication, either an anti-VEGF agent or a steroid, to be delivered directly to the retina. While the procedure is generally quick, some patients report a frightening visual experience during the injection. After the injection, patients might experience temporary blurring of vision, floaters, or mild discomfort, with most recovering within one day.
Treatment frequency varies based on the medication and individual patient response. Anti-VEGF injections often begin with monthly treatments for several months, followed by a “treat-and-extend” approach where intervals between injections are gradually lengthened if the condition remains stable. Dexamethasone implants can provide sustained release for up to six months, potentially reducing the need for frequent visits. Ongoing monitoring with regular eye exams and imaging, such as optical coherence tomography (OCT), is necessary to assess the treatment’s effectiveness and determine if further injections are required. Adherence to the prescribed treatment plan is important for maximizing visual outcomes and preventing recurrence of macular edema.
Complementary and Emerging Therapies
While anti-VEGF injections and steroid implants are primary treatments, other therapies play a role in specific RVO cases or represent future directions. Laser photocoagulation, a long-standing treatment, involves using a laser to create controlled burns on the retina. Grid laser photocoagulation is primarily used for macular edema in branch retinal vein occlusion (BRVO) to reduce swelling by sealing leaking vessels, though it typically stabilizes rather than significantly improves vision. For central retinal vein occlusion (CRVO), panretinal photocoagulation (PRP) is recommended if abnormal new blood vessels (neovascularization) develop, aiming to prevent serious complications like vitreous hemorrhage or neovascular glaucoma.
Vitrectomy surgery, a procedure to remove the vitreous gel from the eye, is generally reserved for more complex RVO complications. It may be considered for persistent vitreous hemorrhage that does not clear on its own or for severe macular edema that has not responded to other treatments. While vitrectomy can improve retinal thickness and visual acuity in some cases, its functional benefits are not always clear. Other surgical techniques have been explored to relieve venous compression or obstruction but are less commonly performed due to variable outcomes and potential complications.
Looking ahead, research continues into novel therapies that aim to improve durability and reduce treatment burden. Emerging areas include new anti-VEGF agents that aim for longer intervals between injections. Gene therapies and stem cell therapies are also being investigated for their potential to regenerate damaged retinal tissue, reduce inflammation, or provide sustained delivery of therapeutic agents. These advanced approaches seek to offer more personalized and less frequent treatment options for RVO patients in the future.