What is CRVO?
Central Retinal Vein Occlusion (CRVO) is a blockage of the central retinal vein, leading to vision problems.
What are common causes of CRVO?
- Age
- Systemic hypertension (HBP)
- Diabetes
- Arteriosclerosis
- Smoking
- Raised intraocular pressure (IOP)
- Hyperviscosity syndromes
What are the key signs of CRVO?
- Flame haemorrhages
- Retinal oedema
- Cotton wool spots
- Dilated and tortuous obstructed vein
- Narrow, sheathed artery
- Indistinct optic nerve head (ONH)
- Decreased visual acuity (VA)
- Relative afferent pupillary defect (RAPD) if ischaemic
What are the common symptoms of CRVO?
- Sudden painless loss of vision
- Blurred vision
- Altitudinal visual loss in BRVO
What are signs of non-ischaemic CRVO?
- Visual acuity ≥ 6/30
- Mild tortuosity and dilation of veins
- Dot/blot and flame-shaped haemorrhages
- Optic disc, retinal, and macular oedema
- ± RAPD
What are the signs of ischaemic CRVO?
- Visual acuity < 6/36
- Capillary closure and retinal hypoxia
- Severe vein tortuosity
- Extensive deep blot and flame-shaped haemorrhages
- Severe macular and disc oedema
- RAPD
What complications can arise in ischaemic CRVO?
- Iris neovascularisation (rubeosis iridis)
- New vessels on the retina (NVE) or disc (NVD)
- Rubeotic glaucoma (90-day glaucoma)
- Vitreous haemorrhage
- Tractional retinal detachment
What is BRVO?
Branch Retinal Vein Occlusion (BRVO) involves a wedge-shaped retinal area following the affected vein.
What are the signs of BRVO?
- Flame haemorrhages
- Dot and blot haemorrhages
- Cotton wool spots
- Hard exudates
- Retinal oedema
- Dilated tortuous veins
How is non-ischaemic BRVO different from ischaemic BRVO?
Signs of occlusion are more extensive in ischaemic BRVO, including neovascularisation (NVE, NVD).
What are differential diagnoses for CRVO?
- Ocular ischaemic syndrome
- Asymmetrical diabetic retinopathy
- Idiopathic retinal telangiectasia (type 1)
- Hypertensive retinopathy
- Choroidal neovascularisation
How should an optometrist manage CRVO?
- Best corrected visual acuity assessment
- Colour fundus photography
- Gonioscopy (if ischaemic CRVO is suspected)
- Optical coherence tomography (OCT)
- IOP check
- Urgent referral to an ophthalmologist and GP
What investigations may be conducted for CRVO?
- OCT
- Fluorescein angiography or OCT angiography
- Gonioscopy (if ischaemic)
- Ultrasound (if vitreous haemorrhage is present)
- Blood tests (FBC, serum glucose, ESR)
What is the treatment for macular oedema in CRVO?
Intravitreal anti-VEGF injections, such as ranibizumab (Lucentis) or aflibercept (Eylea).
What alternative treatments are available for macular oedema in CRVO?
Intravitreal steroids, such as Ozurdex (dexamethasone implant).
What role does macular laser play in treating CRVO?
Macular laser is no longer recommended as first-line therapy, but pan-retinal photocoagulation is used for neovascularisation.
What is the prognosis of non-ischaemic CRVO?
25–34% of cases convert to the ischaemic subtype within 3 years.
What is the prognosis of ischaemic CRVO?
There is a high risk of neovascular complications, such as rubeosis iridis and rubeotic glaucoma, which can lead to blindness.
What are signs of neovascularisation in CRVO?
- Iris neovascularisation (rubeosis iridis)
- New vessels on the retina (NVE) or optic disc (NVD)
What is the risk of rubeotic glaucoma in ischaemic CRVO?
50% of eyes develop iris neovascularisation, with rubeotic glaucoma often occurring 2 weeks to 2 years after CRVO.
What is the usual timeline for rubeotic glaucoma development in CRVO?
Typically occurs around 3 months after CRVO (90-day glaucoma), but can occur between 2 weeks and 2 years.
What is the role of pan-retinal photocoagulation in CRVO?
It is indicated in cases of CRVO with neovascularisation to prevent further complications.
How is visual acuity affected in ischaemic CRVO?
Visual acuity is usually worse than 6/36 due to capillary closure and retinal hypoxia.
What is the importance of gonioscopy in managing CRVO?
It helps assess anterior segment neovascularisation and diagnose ischaemic CRVO.
