Central Retinal Vein Occlusion — How It Works, Benefits & Recovery — Procedure Guide, Recovery & Risks | MyMedicPlus

Central retinal vein occlusion (CRVO) is a blockage of the central retinal vein — the primary venous drainage channel of the entire retina — causing haemorrhage across all four retinal quadrants, disc swelling, macular oedema, and acute visual loss. It is the second most common retinal vascular disorder after diabetic retinopathy. CRVO is classified as non-ischaemic (perfused, 75% of cases) — where macular oedema is the dominant cause of vision loss and prognosis is better — or ischaemic (non-perfused, 25%) where extensive capillary dropout causes permanent retinal damage and a high risk of neovascular complications. Treatment of CRVO focuses on two priorities: reducing macular oedema to restore visual acuity using intravitreal anti-VEGF agents or corticosteroids, and preventing neovascular complications (neovascular glaucoma, vitreous haemorrhage) in ischaemic CRVO using panretinal laser photocoagulation (PRP). A full systemic cardiovascular workup is mandatory as CRVO is a marker for hypertension, hyperlipidaemia, diabetes, glaucoma, and hypercoagulable states. Central retinal vein occlusion (CRVO) is a blockage of the central retinal vein — the primary venous drainage channel of the entire retina — causing haemorrhage across all four retinal quadrants, disc swelling, macular oedema, and acute visual loss. It is the second most common retinal vascular disorder after diabetic retinopathy, with an annual incidence of approximately 0.8 per 1,000 adults over 50 years. CRVO is classified as non-ischaemic (perfused, better prognosis) or ischaemic (greater than 10 disc areas of capillary non-perfusion on fluorescein angiography, higher risk of neovascular glaucoma). Key risk factors include hypertension, hyperlipidaemia, diabetes, glaucoma, and thrombophilia. Treatment is delivered by vitreoretinal specialists (ophthalmologists with retinal subspecialty training) and focuses on treating macular oedema — the primary cause of vision loss — using anti-VEGF injections or intravitreal steroids. Systemic risk factor management by the patient's physician is equally important to prevent second-eye involvement.

All patients with CRVO and macular oedema reducing visual acuity to 6/12 or worse (Snellen) are candidates for intravitreal anti-VEGF treatment, following the CRUISE and COPERNICUS trial protocols that established ranibizumab and aflibercept as effective agents. Treatment initiation should be prompt — within 1–2 weeks of presentation — as earlier intervention is associated with better visual recovery. Ischaemic CRVO is identified on fluorescein angiography by an ischaemic area exceeding 10 disc areas and requires urgent monitoring for iris neovascularisation (rubeosis iridis): when detected, emergency panretinal laser photocoagulation is performed within days to prevent neovascular glaucoma. Patients with CRVO and normal or near-normal visual acuity (6/9 or better) may be observed with monthly monitoring, as some resolve spontaneously. The fellow eye should be assessed for underlying glaucoma, as CRVO risk is significantly elevated in patients with open-angle glaucoma. Systemic cardiovascular risk factors must be identified and managed to reduce the risk of fellow-eye CRVO (5–10% risk at 5 years).

Intravitreal anti-VEGF injection is the first-line treatment for macular oedema secondary to CRVO. The patient is seated or reclined in a procedure chair. Topical anaesthetic drops (proxymetacaine or oxybuprocaine) and povidone-iodine antiseptic drops are applied to the conjunctival sac. A lid speculum holds the eye open. Using a 30-gauge needle, 0.05 mL of the anti-VEGF agent (ranibizumab 0.5 mg, bevacizumab 1.25 mg, or aflibercept 2.0 mg) is injected through the pars plana of the sclera 3.5–4.0 mm posterior to the limbus into the vitreous cavity. Antibiotic drops are prescribed for 3 days. The procedure takes 10–15 minutes. Treatment is given monthly for an initial loading period of 3–6 months, then as needed based on macular OCT (optical coherence tomography) imaging and visual acuity at each visit. Dexamethasone intravitreal implant (Ozurdex, sustained-release 6-month device) is an alternative for patients with anti-VEGF-resistant oedema or those unable to attend frequent injections. Panretinal photocoagulation for neovascularisation is delivered by slit-lamp laser in a single or two-stage session, applying 1,200–1,500 burns to the peripheral ischaemic retina to reduce VEGF production. Intravitreal anti-VEGF injection is the first-line treatment for macular oedema secondary to CRVO. The patient is seated or reclined in a procedure chair. Topical anaesthetic drops and povidone-iodine antiseptic are applied to the conjunctival sac. A lid speculum is inserted and the patient instructed to look away from the injection site. A 30-gauge needle is inserted 3.5–4 mm posterior to the limbus through the pars plana and 0.05 mL of anti-VEGF agent (ranibizumab, bevacizumab, or aflibercept) is injected into the vitreous cavity. The eye is massaged briefly to reduce intraocular pressure and antibiotic drops instilled. The procedure takes 5–10 minutes and is repeated monthly for the initial 3–6 months based on OCT-guided macular thickness monitoring. For ischaemic CRVO with neovascularisation, pan-retinal photocoagulation (PRP) laser is applied to ablate ischaemic retina and reduce VEGF production, delivered as 1,500–2,000 burns in 2–3 sessions.

Anti-VEGF treatment for macular oedema in non-ischaemic CRVO produces substantial visual improvement. The CRUISE trial (ranibizumab) demonstrated a mean gain of +14.9 ETDRS letters at 6 months, with 46.2% of patients gaining 15 or more letters (approximately 3 lines of vision), compared with 16.9% in the sham group. The COPERNICUS trial (aflibercept) showed 56.1% of treated patients gained 15+ letters at 6 months versus 12.3% with sham. In clinical practice, approximately 40–60% of patients with non-ischaemic CRVO achieve a final visual acuity of 6/12 or better with ongoing treatment. Macular OCT-guided treat-and-extend or pro-re-nata (PRN) protocols reduce the injection burden after the loading phase while maintaining visual gains — many patients reach a stable maintenance phase requiring 4–6 injections per year. Panretinal photocoagulation effectively prevents neovascular glaucoma in eyes with ischaemic CRVO, reducing this devastating complication from approximately 50% to less than 5% when performed promptly. Early systemic risk factor treatment (blood pressure control to below 130/80 mmHg, statin therapy for hyperlipidaemia) reduces the risk of fellow-eye involvement.

Intravitreal anti-VEGF injections are generally safe when performed using aseptic technique. The most serious complication is endophthalmitis — intraocular bacterial infection — occurring in approximately 1 in 2,000 to 1 in 3,000 injections with optimal technique; it presents with increasing pain, red eye, and visual loss within 1–5 days and requires emergency intravitreal antibiotic injection. Retinal detachment occurs in fewer than 0.01% of injections. Raised intraocular pressure (IOP) transiently follows injection in most eyes but resolves within 30 minutes; chronic IOP elevation requiring treatment is uncommon. Lens touch during injection is extremely rare with correct technique. Subconjunctival haemorrhage is common, cosmetically alarming but harmless. Systemic cardiovascular events (stroke, MI) from anti-VEGF treatment are a theoretical concern given systemic VEGF suppression; large clinical trials have not demonstrated a significantly increased risk above background population rates. Without treatment, CRVO carries risks of permanent visual loss from persistent macular oedema, vitreous haemorrhage, traction retinal detachment, and neovascular glaucoma — an aggressive, painful secondary glaucoma with a 50% risk in untreated ischaemic CRVO.

Each intravitreal injection is an outpatient procedure taking 20–30 minutes including preparation. Mild discomfort, a gritty sensation, and floaters (from air bubbles in the injection) are common for 24–48 hours. Activities including driving and swimming should be avoided for 24 hours. Antibiotic eye drops are used for 3 days. Patients are instructed to seek urgent review if they experience increasing pain, marked redness, or deteriorating vision after injection — symptoms of endophthalmitis. Macular OCT and visual acuity are reassessed at each monthly visit to guide retreatment decisions. Many patients require ongoing anti-VEGF injections for 1–3 years or longer as CRVO-related macular oedema can be chronic and relapsing. A significant minority of patients with non-ischaemic CRVO have spontaneous resolution of macular oedema within 6–12 months and may eventually need no further treatment. Long-term follow-up with annual retinal review and systemic cardiovascular monitoring is recommended for all CRVO patients.