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This may be done to investigate ankylosing spondylitis. This may cause anterior uveitis, which leads to acute-onset painful vision loss with photophobia, red eye and a constricted pupil. Slit lamp may reveal a hypopyon in the anterior chamber and white precipitates on the cornea. This is not the case here, as the visual loss is painless with no red eye
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MRI lumbosacral spine, including sacroiliac joints
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The patient has sudden onset painless monocular vision loss with a fundoscopy finding suggestive of central retinal artery occlusion. This is usually due to thromboembolism, obstructing blood flow to the retinal artery. Workup for cardiovascular risk factors and a possible thromboembolic cause should be done, including investigations for stroke. The patient is hypertensive and a current smoker, both of which are contributing risk factors as well
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Carotid doppler
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This may be done if suspecting multiple sclerosis, which is the top cause of optic neuritis. Patients usually have painless monocular vision loss over hours to days with colour desaturation. Fundoscopy may show a swollen, blurred optic disc. Lumbar puncture would demonstrate oligoclonal bands in the cerebrospinal fluid
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Lumbar puncture
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HIV is one of the systemic causes of eye disease, including HIV retinopathy, cytomegalovirus (CMV) retinitis, herpes simplex virus (HSV) keratitis or retinitis and toxoplasmosis. CMV retinitis tends to be the most common HIV-related eye condition, causing loss of central vision, blind spots, floaters or flashing lights. Fundoscopy typically shows a "pizza pie" appearance due to haemorrhagic retinal necrosis
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Human immunodeficiency virus (HIV) testing
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This would be appropriate if suspecting acute anterior ischaemic optic neuropathy, which may occur due to giant cell arteritis (arteritic) or atherosclerosis (non-arteritic). Presenting symptoms include a sudden onset painless monocular vision loss with deterioration of colour vision, and fundoscopy reveals unilateral optic disc oedema with flame-shaped haemorrhages. In giant cell arteritis, erythrocyte sedimentation rate (ESR) would be raised, and temporal artery biopsy is the gold standard investigation
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Temporal artery biopsy
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GCA is also a possible cause of central retinal artery occlusion??
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In hindsight, I think the lack of Hx pointing towards GCA + the risk factors of cardioembolic cause would suggest an ECHO is the most correct answer -sucks to suck though because I also got this wrong!
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j.g.73
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Positive Whiff Test
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# Summary

Central Retinal Artery Occlusion (CRAO) is an ocular condition marked by sudden, painless vision loss that typically occurs within seconds. The condition is less common than retinal vein occlusion and results in faster deterioration of vision. Key signs and symptoms include a pale retina with a cherry red spot at the macula, carotid bruits, hypertension, atrial fibrillation, diabetes mellitus, smoking, or hyperlipidaemia. Key investigations include fundoscopy and patient history and examination. Management involves treating the primary cause and may include anticoagulant therapy or ocular massage.

# Definition

Central Retinal Artery Occlusion (CRAO) is a serious ocular condition characterized by a sudden, painless loss of vision. This abrupt vision loss typically occurs over seconds and is due to the occlusion of the central retinal artery.


# Epidemiology

CRAO is less common than retinal vein occlusion. However, it is associated with a faster rate of vision deterioration.


# Pathophysiology

The retina receives its blood supply from two sources:

1. Central retinal artery: 

   - The internal carotid artery's first branch is the ophthalmic artery, which subsequently branches to the central retinal artery

   - The central retinal artery enters the eye at the optic disc, then branches into the superior and inferior retinal arteries, before branching into temporal and nasal subdivisions, which each supply a quadrant of the retina


2. Choriocapillaries:
   - The peripheral retina receives its blood supply from the capillaries of the choroid, which are branches of the ciliary artery


Therefore, the more proximal an occlusion is, the worse the effect on vision:

- Occlusion of the retinal artery before branching is termed **central retinal artery occlusion** (CRAO)
- Occlusion after branching is termed **branch retinal artery occlusion** (BRAO)

Patients often present with the 'cherry red spot' finding on fundoscopy (see below) and this refers to the fact that the macula/fovea (responsible for central vision) are spared in CRAO. This is because the macula is supplied by the cilioertinal artery which is usually not affected in CRAO.

# Aetiology

CRAO is essentially a stroke that affects the eye, so it has similar risk factors and pathophysiology.

Often the specific aetiology of a CRAO remains unclear, but the most common causes are:

- Atherosclerosis – roughly 80% of cases
- Embolism – carotid, cardiac or aortic
- Inflammatory (e.g. GCA, SLE)
- Thrombophilia (e.g. protein S or C deficiency, antiphospholipid syndrome)


# Signs and Symptoms 

- In CRAO, patients present with sudden-onset painless loss of vision that typically occurs over seconds – in almost all cases, vision is reduced to counting fingers. 
- Patients may also report a history of amaurosis fugax.

The classic examination finding is a pale retina with a 'cherry red spot' at the macula. Patients may also have a relative afferent pupillary defect.

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Patients should also be examined/investigated for risk factors for CRAO including: 

- Carotid bruits
- Hypertension
- Atrial fibrillation
- Diabetes mellitus
- Smoking
- Hyperlipidaemia

# Differential Diagnosis

Differential diagnoses for CRAO should include other conditions that can cause sudden vision loss. These may include:

- Retinal Vein Occlusion: Characterised by sudden, painless vision loss, floaters, and decreased peripheral vision.
- Retinal Detachment: Presenting with flashing lights, floaters, or a shadow in the peripheral vision.
- Optic Neuritis: Symptoms may include pain, vision loss, and abnormalities in colour vision.
- Ischemic Optic Neuropathy: Characterised by sudden, painless vision loss and a pale, swollen optic disc.

# Investigations

- Primary investigations for CRAO involve fundoscopy and a thorough patient history and examination. 
- Imaging techniques such as optical coherence tomography (OCT) and fluorescein angiography may also be utilized.

# Management 

The reversibility of damage to the retina decreases with time. Therefore, the window of time in which treatment is likely to be beneficial is short. Evidence to date suggests that, beyond 90–100 minutes, vision is unlikely to improve with treatment.

The aim of treatment in the acute setting is to reperfuse the ischaemic retina as quickly as possible. Some centres will advocate the following methods, but there is no proven benefit in the literature:

- Ocular massage – aiming to dislodge the embolus
- Vasodilation with isosorbide dinitrate
- Anterior chamber paracentesis – aiming to reduce IOP to help dislodge the embolus

Long-term management consists of secondary prevention of further ischaemic end-organ damage.

# Prognosis 

The visual prognosis is unfortunately very poor with CRAO as the neural layer of the retina atrophies swiftly without a blood supply. Only 30% of patients will have any improvement in vision after presentation.

# Branch Retinal Artery Occlusion

BRAO presents similarly to CRAO, but only some of the visual field is lost because only some of the retinal blood supply is occluded.

Management is the same as for CRAO and mainly consists of long-term secondary prevention.

# References

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

[Further information on Patient.co.uk](https://patient.info/doctor/retinal-artery-occlusions)

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Fundoscopy showing the classic 'cherry red spot' seen in central retinal artery occlusion.
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Central retinal artery occlusion (CRAO)
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Ophthalmology
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A carotid Doppler is an important diagnostic tool for evaluating sudden onset painless monocular vision loss, especially when fundoscopy findings suggest central retinal artery occlusion (CRAO). This test helps identify significant stenosis or emboli in the carotid artery, which can be a source of the arterial blockage leading to CRAO.
A 75-year-old male presents to the Emergency Department with sudden vision loss in his right eye. His past medical history includes hypertension, and he is a smoker.

His right eye is painless, and there is no conjunctival redness. Fundoscopy reveals a red spot at the macula.

Which of the following tests are most appropriate in investigating the underlying cause?
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