QuestionSBA
QuestionChoice
Vertebral artery dissection presents as a severe occipital headache as well as posterior fossa ischaemic symptoms manifesting as ataxia, dysarthria, lateral medullary syndrome, and visual symptoms. It would not present with monocular vision loss or with the fundoscopy findings above
33122
e
Vertebral artery dissection
QuestionChoice
Optic neuritis is a gradual worsening of vision due to inflammation of the optic nerve, such as in multiple sclerosis. It would not present with sudden monocular vision loss and would not produce intra-retinal haemorrhages on fundoscopy
33121
d
Optic neuritis
QuestionChoice
Retinal detachment typically presents with amaurosis fugax, floaters, and flashing lights. If the retinal detachment were so severe that it would cause full monocular blindness, then it would be visible on fundoscopy. Given the patient's history of antiphospholipid syndrome with a hypercoagulable state, thromboembolic disease is more likely such as central retinal artery/vein occlusion
33120
c
Retinal detachment
QuestionChoice
Usually, CRVO presents in older patients with cardiovascular history, diabetes, or hyperlipidaemia. This patient has antiphospholipid syndrome, a condition known to cause a hypercoagulable state, and so puts them at increased risk of thromboembolic disease. Sudden onset monocular vision loss with relative afferent pupillary defect (RAPD) implies a lesion of the optic nerve. As the retinal artery and veins are the sole source of blood supply to the retina, occlusion of either causes severe damage, blindness, and macular oedema
33118
a
Central retinal vein occlusion (CRVO)
QuestionChoice
Ocular migraines can present with transient monocular blindness or flashing lights. They would not produce the fundoscopy findings shown above
33119
b
Ocular migraine
QuestionComment
CRVO - 'stormy sunset' 
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subscriber
Sir Pep Guardiola
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# Summary

Central retinal vein occlusion (CRVO) and Branch retinal vein occlusion (BRVO) are conditions that occur when the central retinal vein or its branches are occluded by a thrombus, respectively. They present with sudden, painless loss of vision or visual field defects. Classic signs include numerous flame haemorrhages, dot and blot haemorrhages, cotton wool spots, retinal oedema, and dilated or tortuous retinal veins. Investigations aim to identify the underlying aetiology and may include a full blood count, ESR, CRP, and renal, liver and lipid profiles. Management is generally conservative, though some situations may require laser photocoagulation or intravitreal anti-VEGF injections.

# Definition

Central retinal vein occlusion (CRVO) and Branch retinal vein occlusion (BRVO) are distinct conditions in which the central retinal vein or one of its branches, respectively, is occluded by a thrombus.

# Epidemiology

CRVO and BRVO are more common than central retinal artery occlusion. Risk factors for these conditions are divided into atherosclerotic and haematological categories. 


| Atherosclerotic | Haematological |
|-----------|------|
| Age| Protein S, protein C or antithrombin deficiency |
| Smoking | Factor V Leiden|
| Obesity | Multiple myeloma |
| Hypertension| Glaucoma |
|Diabetes | Antiphospholipid syndrome |



# Signs and symptoms

CRVO typically presents with sudden, painless loss of vision or visual field defects. In BRVO, loss of vision may only be noticeable by patients if it affects the macula. 

Ischaemic CRVO usually causes much worse reduced visual acuity (6/60 or worse).

The classic fundoscopy description of CRVO is a 'stormy sunset', with findings that include:

- Numerous flame haemorrhages
- Dot and blot haemorrhages
- Cotton wool spots
- Retinal oedema
- Dilated or tortuous retinal veins
- Visual field defects, depending on the site of the occlusion

Note: For BRVO, these signs are present but only in the affected segment of the retina.

# Differential diagnosis

* **Diabetic Retinopathy:** Diabetic retinopathy, particularly the macular edema subtype, can lead to visual impairment and retinal swelling similar to CRVO. Distinguishing between the two conditions is crucial for appropriate management.
* **Hypertensive Retinopathy:** Hypertensive retinopathy, resulting from long-standing high blood pressure, may manifest as retinal hemorrhages and cotton-wool spots. A detailed medical history and blood pressure evaluation can help differentiate hypertensive retinopathy from CRVO.
* **Ocular Ischemic Syndrome (Carotid Artery Disease):** Ocular ischemic syndrome can present with similar retinal findings due to compromised blood flow to the eye. It often results from carotid artery disease, which can be detected through carotid artery imaging.
* **Retinal Artery Occlusion:** Retinal artery occlusion, such as central retinal artery occlusion (CRAO), can cause sudden vision loss and retinal pallor, similar to CRVO. However, arterial occlusions typically have a more abrupt and severe onset.
* **Retinal Detachment:** Retinal detachment may cause visual disturbances and can sometimes be mistaken for CRVO. Examination findings, including retinal detachment features like a detached retina, are crucial for differentiation.
* **Macular Hole or Pucker:** Macular hole or epiretinal membrane (macular pucker) can result in distorted or decreased vision, resembling CRVO symptoms. Optical coherence tomography (OCT) can help distinguish these conditions.
* **Optic Neuropathy:** Optic neuropathies, such as non-arteritic anterior ischemic optic neuropathy (NAION) or arteritic anterior ischemic optic neuropathy (AAION), can lead to sudden vision loss. 

# Investigations

During bedside examination, fundoscopy findings (more so for ischaemic CRVO) include: macular oedema, optic nerve head oedema, **flame-haemorrhages,** venous tortuosity and cotton wool spots. Additionally, patients will have reduced visual acuity so assessing this with a Snellen chart will help aid diagnosis. In advanced disease, a relative afferent pupillary defect may also be present.

Investigations aim to identify the aetiology of the occlusion and may include:

- Full blood count
- Erythrocyte sedimentation rate (ESR) 
- C-reactive protein (CRP)
- Renal, liver and lipid profiles
- Clotting screen

Further screening tests for thrombophilia should be carried out if the patient has a family history of clotting disorders.

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# Management

Most patients with CRVO or BRVO are managed conservatively, as there is no evidence to support the use of anticoagulation or haemodilution in the acute setting. Specific treatments may be necessary in some situations:

- Retinal neovascularisation is managed with laser photocoagulation
- Macular oedema is treated with intravitreal anti-VEGF injections. If anti-VEGF is contraindicated (e.g., stroke or MI within 3 months, pregnancy), corticosteroids are administered

# Complications

- Neovascularisation – ischaemia in the retina promotes the production of vascular endothelial growth factor (VEGF), which stimulates new vessel growth
- Vitreous haemorrhage – new vessels are fragile and can bleed, leading to vitreous haemorrhage
- Hyphaema – neovascularisation in the iris can lead to bleeding in the anterior chamber (hyphaema); bleeding can obstruct the outflow of aqueous leading to neovascular (rubeotic) glaucoma

# References

Denniston AK, Murray PI. Oxford Handbook of Ophthalmology. Fourth Edition. Oxford University Press. 2018.

[See Patient UK for a comprehensive review of CRVO](https://patient.info/doctor/retinal-vein-occlusions)
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Picture
Fundoscopy of patient with CRVO, Credit: Werner JU, Böhm F, Lang GE, Dreyhaupt J, Lang GK, Enders C, CC BY 4.0 
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Topic
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Ophthalmology
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Central retinal vein occlusion (CRVO)
Topic
16
Ophthalmology
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Antiphospholipid syndrome is a significant risk factor for central retinal vein occlusion (CRVO) as it promotes hypercoagulability, increasing the likelihood of blood clot formation in the retinal veins.
A 28-year-old man with antiphospholipid syndrome presents with sudden painless monocular vision loss while driving. Fundoscopy shows macular oedema and multiple intra-retinal haemorrhages in each quadrant in the right eye. There is also a relative afferent pupillary defect.

Which of the following is the most likely diagnosis?
a