Central Retinal Vein Occlusion (CRVO): Symptoms, Diagnosis & Treatment in Birmingham

CRVO occurs when a blood clot blocks the central retinal vein at the optic nerve head, preventing blood from draining properly from the retina. This blockage causes blood and fluid to leak into the retina, resulting in haemorrhages, swelling (macular oedema), and potential vision loss. ​

Unlike branch retinal vein occlusion (BRVO), which affects only part of the retina, CRVO impacts the entire retina because the main drainage vein is blocked.

CRVO usually affects only one eye and is more common in people over 60, particularly those with high blood pressure, diabetes, or glaucoma. Although rarer, it is possible to have bilateral CRVO.

Ischaemic vs Non-Ischaemic CRVO

CRVO is classified into two types based on the severity of retinal blood flow disruption:

Non-Ischaemic CRVO: The milder form where some blood flow continues through the retina. Many patients retain reasonable vision, and approximately 50% improve without treatment. However, non-ischaemic CRVO can progress to the ischemic type without proper monitoring. ​ ​

Ischaemic CRVO: The severe form where extensive areas of the retina lose blood supply. Vision is typically much worse, and complications such as abnormal new blood vessel growth (neovascularisation) and secondary glaucoma are more common. Ischemic CRVO requires intensive treatment and close monitoring.

OCT angiography helps differentiate between these types by mapping retinal perfusion, which guides treatment urgency and intensity.

Most patients with CRVO experience sudden vision changes in one eye:

​Blurred or distorted central vision

• Sudden painless vision loss

• Dark patch or blind spot in central vision

• Difficulty reading or recognising faces

Mild CRVO may cause minimal symptoms initially, but vision can deteriorate over days to weeks as macular swelling develops.

​Severe ischaemic CRVO can cause eye pain, redness, and irritation if complications like secondary glaucoma develop.

If you experience sudden vision loss in one eye, seek urgent assessment. Early diagnosis and treatment significantly improve the chances of preserving vision.

Mr. Sahota uses comprehensive imaging and clinical examination to diagnose CRVO and determine severity:

Dilated Fundus Examination: Identifies characteristic signs including widespread retinal haemorrhages, dilated tortuous veins, cotton-wool spots, and optic disc swelling.

​OCT (Optical Coherence Tomography): Measures macular thickness and quantifies fluid (macular oedema) to guide treatment decisions and monitor response.

​OCT Angiography (OCT-A): Non-invasive imaging that maps retinal blood flow and identifies areas of capillary non-perfusion (ischaemia) without dye injection. OCT-A can be valuable for differentiating ischemic from non-ischemic CRVO.

​​Risk factor assessment includes checking blood pressure, blood sugar levels, and sometimes blood clotting disorders, particularly in younger patients or those with bilateral CRVO.

The primary goal of CRVO treatment is to reduce macular oedema and preserve central vision. Mr. Sahota offers evidence-based treatments supported by major clinical trials.​

​Anti-VEGF Injections

Anti-VEGF (vascular endothelial growth factor) drugs are the first-line treatment for macular oedema secondary to CRVO.

​How it works: When the retinal vein is blocked, the retina releases VEGF, a protein that causes blood vessels to leak fluid. Anti-VEGF drugs block this protein, reducing macular swelling and improving vision.

​Available agents:

• Eylea (aflibercept)

• Vabysmo (faricimab)

• Lucentis (ranibizumab)

Evidence: The landmark CRUISE trial showed that ranibizumab produced an average gain of +15 letters at 6 months in CRVO patients. The COPERNICUS and GALILEO trials demonstrated similar results with aflibercept, achieving approximately +16 letter gains.

​The recent COMINO trial showed that faricimab (Vabysmo) achieved +17 letter gains, comparable to Eylea, with the potential for extended dosing intervals.

​Treatment schedule: Typically begins with monthly injections for 3-6 months (loading phase), followed by individualised maintenance dosing—often every 8-12 weeks—based on OCT findings and visual response.

​​Ozurdex Steroid Implant

Ozurdex (dexamethasone intravitreal implant) is an alternative treatment that provides sustained steroid release over 4-6 months.

​How it works: The tiny implant is injected into the eye and gradually releases dexamethasone, a potent anti-inflammatory steroid that reduces macular swelling.

​Evidence: The GENEVA trials demonstrated that Ozurdex significantly accelerates visual improvement in CRVO compared to placebo, with shorter time to gain ≥15 letters.

​Who benefits: Ozurdex may be preferred for pseudophakic patients (those who have had cataract surgery), patients unable to attend monthly appointments, or those with insufficient response to Anti-VEGF therapy.

​Side effects: Ozurdex increases the risk of intraocular pressure elevation (in between 1 in 6, and 1 in 3 patients) and cataract formation in the natural lens. Close monitoring is essential as glaucoma can develop with repeated steroid implants.

​Laser Treatment

Laser photocoagulation has a limited role in CRVO. It may be used to treat peripheral retinal ischaemia or abnormal new blood vessels in ischemic CRVO, but it does not improve central vision or reduce macular oedema.

Your first appointment includes:

• Comprehensive medical and ocular history

• Visual acuity testing

• Dilated fundus examination

• OCT and OCT angiography imaging

• Classification as ischaemic or non-ischaemic CRVO

• Discussion of treatment options tailored to your findings

Same-week treatment can often be arranged to begin reducing macular oedema immediately.

​Loading Phase (Months 1-6)

Anti-VEGF pathway: Monthly injections for the first 3-6 months with OCT monitoring at each visit. Vision typically begins improving within the first month, with maximum benefit by 6 months.

​Ozurdex pathway: Single implant provides 4-6 months of steroid release. Repeat implants may be given as fluid recurs.

​Maintenance Phase (Beyond 6 Months)

As macular oedema stabilises, injection intervals are gradually extended based on OCT findings. Some patients maintain dry maculae with injections every 3-4 months, while others require more frequent treatment.

​Close monitoring for complications—particularly neovascularisation in ischaemic CRVO—continues for at least 6 months.

Non-ischaemic CRVO: Approximately 50% of patients experience spontaneous improvement. With Anti-VEGF treatment, visual outcomes are generally good, with many patients gaining 3 or more lines on the eye chart.​

​Ischaemic CRVO: Prognosis is more guarded. While Anti-VEGF treatment provides meaningful vision improvement, final vision is often more limited due to permanent retinal damage from severe ischaemia.

​Complications: The main risk in ischaemic CRVO is neovascular glaucoma, which develops in approximately 20% of untreated cases within 6 months. Anti-VEGF therapy reduces this risk significantly.

​Early diagnosis and treatment with consultant-led care offer the best chance of preserving functional vision.

Private CRVO treatment costs in Birmingham depend on the drug used, injection frequency, and facility fees. For detailed pricing information including consultation fees, imaging costs, and per-episode totals, see our dedicated CRVO treatment cost guide.

Mr. Sahota provides expert CRVO diagnosis and treatment at:

Edgbaston Eye Consultants: 22 George Road, Edgbaston, Birmingham B15 1PJ

The Westbourne Centre: 53 Church Road, Edgbaston, Birmingham B15 3SJ

Both clinics offer convenient access from Solihull, Sutton Coldfield, Harborne, and throughout the West Midlands, with flexible appointment times and online booking

Is CRVO an emergency?

 Yes—sudden vision loss from CRVO requires urgent assessment. Early treatment significantly improves visual outcomes. Contact the clinic immediately for same-day triage and treatment where appropriate.

How many injections will I need? Most CRVO patients require monthly injections for 3-6 months initially, followed by individualised maintenance—often every 8-12 weeks. Total treatment duration varies by response.

Can CRVO affect my other eye? CRVO usually affects only one eye. The risk of developing CRVO in the second eye is low (approximately 1% per year), though managing risk factors like blood pressure and diabetes reduces this risk further.

What's the difference between ischaemic and non-ischaemic CRVO? Non-ischaemic CRVO is milder with better prognosis, while ischaemic CRVO involves severe retinal blood flow loss and higher complication risk.

​Can vision fully recover from CRVO?

 Many non-ischaemic CRVO patients achieve good vision with treatment. Ischemic CRVO outcomes are more variable—while significant improvement is possible, some permanent vision loss may remain due to retinal damage.

Can private medical insurance cover CRVO treatment? SomePMI policies cover Anti-VEGF and Ozurdex for CRVO when medically indicated. Check your policy coverage and excess before starting treatment

Schedule online for urgent CRVO assessment with Mr. Dilraj Sahota.

Or call +44 121 630 4580

This guide provides general educational information about central retinal vein occlusion and does not replace personalised medical advice from a qualified clinician. Individual treatment requirements, prognosis, and costs vary based on CRVO severity, ischemic status, imaging findings, and medical history. A written treatment plan will be provided after consultation. If you experience sudden severe vision loss, seek urgent care immediately via emergency services or your nearest eye hospital.

​Last updated: October 2025