Central Retinal Artery Occlusion; Central retinal vein occlusion

Question 1

What is the most common cause of CRAO? [1]

Answer 1

Atherosclerotic disease is the most common cause of CRAO
- CRAO occurs due to occlusion of the retinal artery, usually due to an embolic event secondary to atherosclerotic disease.
- The central retinal artery supplies the surface of the optic nerve and inner retina.

Question 2

Describe the arterial anatomy that is linked to CRAO [1]

Answer 2

The first branch of the internal carotid artery is the ophthalmic artery, which supplies the eye. The retina is supplied by two main arterial systems that arise from the ophthalmic artery:
* Retinal arteries
* Ciliary arteries

The retinal artery divides into the superior and inferior branches, which further divides into nasal and temporal terminal branches.

These arteries supplies the inner retina.

Question 3

Describe the typical presentation of CRAO [+]

Answer 3

Patients with central retinal artery occlusion (CRAO) present with visual loss which is:
* Sudden onset (within seconds)
* Monocular
* Painless
* Severely reduced visual acuity
* Central visual sparing (15-30%): May suggest patent cilioretinal artery.

Question 4

Describe the signs of CRAO [+]

Answer 4

Relative afferent pupillary defect (RAPD):
- Asymmetrical pupillary reaction to light due to optic nerve disease.

Pale retina

‘Cherry red spot’: Suggestive macular sparing due to patent blood supply via the cilioretinal artery.

Retinal emboli: May be seen in up to 40%.

Question 5

If needed, the diagnosis of CRAO can be confirmed using []

Describe this investigation and what would present like in CRAO [1]

Answer 5

If needed, the diagnosis can be confirmed using fluorescein angiography
- During this procedure fluorescent dye is inserted intravenously. This allows assessment of the retinal vessels using imaging. In **CRAO there is usually evidence of slowed flow or a filling defect. **

Question 6

In the work-up of CRAO, it is critical to exclude [].

Answer 6

In the work-up of CRAO, it is critical to exclude GCA.

Question 7

Long term Mx of CRAO? [+]

Answer 7

CRAO is a form of ischaemic end-organ damage. Hence patients who have experienced CRAO are at increased risk of future ischaemic events such as myocardial infractions and ischaemic cerebral strokes

Long term management depends on the underlying cause of CRAO:
* Carotid source of emboli: carotid endarterectomy to correct stenosis of the carotid arteries. Stenosis of greater than 50% is classed as moderate to severe and requires surgery.
* Cardiac source of emboli: long term anticoagulation is usually recommended
* Uncertain aetiology: anti-platelet therapy and atherosclerosis risk factor modification (e.g. statins, smoking cessation and diet changes)

Question 8

Describe the acute Mx of CRAO [5]

Answer 8

Ideally, treatment should be administered within 6 hours of onset to be effective.

1. Intra-arterial thrombolysis: typically urokinase is administered via direct ophthalamic artery catheterisation
2. In patients who are not candidates for thrombolysis but still present within a reasonable timeframe from onset, anterior chamber paracentesis can be completed. This aims to reduce intra-ocular pressure with the hope that it dislodges the embolus.

NB: The evidence supporting acute treatment of CRAO is limited. Treatment is usually attempted within 24 hours of presentation, but should be completed within 6 hours to improve efficacy.

Question 9

Lecture

Describe the difference in presentation between central and branch RAO [2]

Answer 9

Question 10

Visual loss in CRVO is secondary to the development of [] This develops following the venous occlusion.

Answer 10

Visual loss in CRVO is secondary to the development of macular oedema. This develops following the venous occlusion.

Question 11

Describe the pathophysiology of central retinal vein occlusion [+]

Answer 11

Thrombosis in the retinal vein causes increased pressure in the vessels draining from the eye

This causes transudation of blood products into the retina from the venous capillary beds, leading to increased interstitial oncotic pressure that results in macular oedema and capillary ischaemia.

GeekyMedics:
- Pathophysiology: atherosclerotic thickening of retinal arteries compresses retinal veins, leading to endothelial damage, turbulent blood flow, thrombus formation, ischaemia, infarction, vessel leakage, and neovascularisation.

Question 12

Describe the presentation of CRVO [+]

Answer 12

The main symptom is sudden, painless unilateral visual loss. The onset of visual loss is more gradual than with a retinal artery occlusion.

BRVO typically presents with partial visual field defect and metamorphopsia. BRVO can also be asymptomatic if the macula is spared.

90% of patients with ischaemic CRVO have visual acuity of 6/60 or worse

Relative afferent pupillary defect

Question 13

Describe the fundoscopy findings of CRVO [+]

Answer 13

General:
- dot/blot haemorrhages, vascular dilatation and tortuosity of retinal veins (distribution of these dictates BRVO or CRVO with one, or four vein territories respectively involved)

Macular oedema
- hard exudate

Evidence of ischaemia:
- haemorrhages, cotton wool spots, optic disc swelling

Neovascular complications:
- neovascularisation and iris rubeosis, vitreous haemorrhage

Question 14

Describe the fundoscopy of this CRVO [3]

Answer 14

Fundus photograph showing widespread haemorrhages and axonal congestion (cotton wool spots; white circles) upstream of the venous occlusion.4

Question 15

Answer 15

Figure 3. Ischaemic central retinal vein occlusion.6

Question 16

A key differential to CRVO is branch retinal vein occlusion (BRVO).

Describe the difference in pathophysiology and how it would present / be found differently [2]

Answer 16

A key differential is branch retinal vein occlusion (BRVO) - this occurs when a vein in the distal retinal venous system is occluded and is thought to occur due to blockage of retinal veins at arteriovenous crossings. It results in a more limited area of the fundus being affected.
- macular oedema is infrequently seen on fundoscopy

Question 17

Non-ischaemic CRVO: Treatment strategy depends on the severity of presenting visual deficits.

Describe the management plan for visual acuity of:
- 6/12 or better
- 6/96 or better
- less than 6/96

Answer 17

6/12 or better
- Can observe with regular follow up as may spontaneously resolve. However, 30% may convert to an ischaemic CRVO over three years due to an increase in the area of non-perfusion

6/96 or better:
- Intravitreal anti-VEGF therapy indicated. Ranibizumab and aflibercept are two anti-VEGF agents recommended by NICE. Monthly intravitreal injections until stable visual acuity achieved.

Less than 6/96
- High risk of ocular neovascularisation (e.g. progression to ischaemic CRVO), and improvement with anti-VEGF therapy alone unlikely to produce improvement in visual acuity. Therefore patients should be closely observed for progression to ischaemic CRVO.

Question 18

Describe the mx of ischaemic CRVO [2]

Answer 18

Urgent pan-retinal photocoagulation (PRP) where neovascularisation is seen, with repeat at 2 weeks if required.

In the absence of neovascularization, monthly follow-up to monitor. Where this is impractical, prophylactic PRP may be considered.

Macular oedema managed with anti-VEGF therapy.

Question 19

Describe the three classifications of diabetic retinopathy? [2]

Answer 19

non-proliferative diabetic retinopathy (NPDR) marked by:
- microaneurysms
- retinal haemorrhages (dot haemorrhages)
- hard exudates (yellowish deposits of lipid due to vessel leakage)

proliferative diabetic retinopathy (PDR) (more advanced and severe stage), is characterized by:
- the proliferation of new, fragile blood vessels that can bleed into the vitreous, leading to vision loss due to VEGF upregulation
- can be new vessels on disc (NVD) OR new vessels everywhere (NVE)

Diabetic maculopathy:
- Presence of any retinopathy within 1 disc diameter around macula:
Can be:
- Focal
- Diffuse
- Ischaemic

Question 20

What are the different types of classification of hard exudates in non-proliferatve retinopathy? [3]

Answer 20

Mild
Moderate
Severe: Cotton wool spots (arrow): areas of retinal ischaemia

Question 21

What does this yellow arrow depict in non-proliferative diabetic retinopathy? [1]

Answer 21

Hard exudates

Question 22

What does the yellow arrow on the image of non-proliferative retinopathy depict? [1]

Answer 22

Lipid exudates

Question 23

Describe what the arrows & circle depict on this image of non proliferative diabetic retinopathy [3]

Answer 23

intraretinal microvascular abnormality (IRMA; green arrow)

venous beading and segmentation (blue arrow)

cluster haemorrhage (red circle)

featureless retina suggestive of capillary non-perfusion (white ellipse)

Question 24

What is the arrow pointing to on this NPDR? [1]

Answer 24

**Cotton wool spots** (severe NPDR

Question 25

How can PDR lead to blindness? [4]

Answer 25

- New blood vessels are very **fragile**; easily break and leak - Retinal haemorrhage can lead to **acute** **blindness** - If repeated; leads to **fibrosis** & **scarring** - Can lead to: **tractional retinal detachment:** when scar tissue or other tissue grows on your retina and **pulls it away from the layer underneath**

Question 26

Which pathology is depicted? [1]

Answer 26

**Diabetic maculopathy:** hard exudates near to the macula

Question 27

What is depicted in this image? [1]

Answer 27

**Proliferative diabetic retinopathy:** extensive vitreous haemorrhage obscuring most of fundus (white circle)}

Question 28

What is depicted in this image? [1]

Answer 28

**Non-proliferative diabetic retinopathy:** blot haemorrhage (white circle)}

Question 29

Describe what is happening in this image [1]

Answer 29

**Proliferative diabetic retinopathy:** **NVD** new vessels on the optic disc

Question 30

What is the management of diabetic retinopathy? [5]

Answer 30

**Laser photocoagulation** **Anti-VEGF medications** such as **ranibizumab, bevacizumab & Aflibercept** **Vitreoretinal surgery** (keyhole surgery on the eye) may be required in severe disease or a vitrectomy may be necessary to clear severe vitreous hemorrhage or to relieve tractional retinal detachment. Corticosteroids (**triamcinolone**, **dexamethasone implant**) can also be used, particularly in refractory DME. **Pan-retinal photocoagulation (PRP)**: laser used to make small burns evenly across the peripheral retina - should make blood vessels shrink and dissapear

Question 31

1. A 67 year old woman suddenly loses the vision in her left eye. She is in good health with no history of eye disease and is not taking any medication. Her right eye is normal. The left has vision reduced to hand movements only. The left pupil reacts sluggishly to light. Her fundal photograph is shown (see image). Which is the cause of her sudden loss of vision? A. Branch retinal artery occlusion B. Branch retinal vein occlusion C. Central retinal artery occlusion D. Central retinal vein occlusion E. Cilioretinal vein occlusion

Answer 31

1. A 67 year old woman suddenly loses the vision in her left eye. She is in good health with no history of eye disease and is not taking any medication. Her right eye is normal. The left has vision reduced to hand movements only. The left pupil reacts sluggishly to light. Her fundal photograph is shown (see image). Which is the cause of her sudden loss of vision? A. Branch retinal artery occlusion **B. Branch retinal vein occlusion** C. Central retinal artery occlusion D. Central retinal vein occlusion E. Cilioretinal vein occlusion

Question 32

Which is the cause of her sudden loss of vision? A. Branch retinal artery occlusion B. Branch retinal vein occlusion C. Central retinal artery occlusion D. Central retinal vein occlusion E. Cilioretinal vein occlusion

Answer 32

Which is the cause of her sudden loss of vision? A. Branch retinal artery occlusion B. Branch retinal vein occlusion C. Central retinal artery occlusion **D. Central retinal vein occlusion** E. Cilioretinal vein occlusion

Question 33

Which is the cause of her sudden loss of vision? A. Branch retinal artery occlusion B. Branch retinal vein occlusion C. Central retinal artery occlusion D. Central retinal vein occlusion E. Cilioretinal vein occlusion

Answer 33

**C. Central retinal artery occlusion**

Question 34

A 54-year-old man with Type 2 diabetes mellitus for 6 years attends for retinal screening, and is told he has mild background diabetic retinopathy with no other concerning findings. What signs are likely to be seen on his retinal photograph? cotton wool spots throughout retina hard exudates close to the macula microaneurysms multiple dot and blot haemorrhages close to the macula new vessel formation

Answer 34

A 54-year-old man with Type 2 diabetes mellitus for 6 years attends for retinal screening, and is told he has mild background diabetic retinopathy with no other concerning findings. What signs are likely to be seen on his retinal photograph? cotton wool spots throughout retina hard exudates close to the macula **microaneurysms** multiple dot and blot haemorrhages close to the macula new vessel formation

Question 35

Answer 35

Periorbital cellulitis

Question 36

Answer 36

Haemorrhage

Question 37

Answer 37

**Viral conjunctivitis** - normally adenovirus

Question 38

Answer 38

**Allergic conjunctivitis**

Question 39

Answer 39

**Blepharitis**

Question 40

Name three causes that could be stopping this red reflex [3]

Answer 40

Anything that blocks the reflection of light - E.g. cataracts, vitreous haemmorrhage, retinoblastoma

Question 41

During your fund. Exam you reach the optic disc. What three things should you assess at this stage? [3]

Answer 41

Question 42

Describe your findings from this image [3]

Answer 42

Have a system: **Disc margins**: - **Bluured** **Retinal veins**: - swollen **Other features**: - Retinal haemorrhages around disc **SHOWS papilloedema** - indicates intracranial hypertension

Question 43

Answer 43

Figure 1. Retinal photograph of the right eye showing **papilloedema** in a patient with IIH

Question 44

Answer 44

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Answer 45

Question 46

Answer 46

Question 47

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Question 48

Answer 48

Question 49

Answer 49

Question 50

Answer 50

Question 51

When would you use a blue and green filter on a fundoscopy exam? [2]

Answer 51

Question 52

Describe the three classifications of diabetic retinopathy? [2]

Answer 52

**non-proliferative diabetic retinopathy (NPDR)** marked by: - microaneurysms - retinal haemorrhages (dot haemorrhages) - hard exudates (yellowish deposits of lipid due to vessel leakage) **proliferative diabetic retinopathy (PDR)** (more advanced and severe stage), is characterized by: - the proliferation of new, fragile blood vessels that can bleed into the vitreous, leading to vision loss due to VEGF upregulation - can be new vessels on disc (NVD) OR new vessels everywhere (NVE) **Diabetic maculopathy:** - Presence of any retinopathy within 1 disc diameter around macula: Can be: - Focal - Diffuse - Ischaemic

Question 53

How can PDR lead to blindness? [4]

Answer 53

- New blood vessels are very **fragile**; easily break and leak - Retinal haemorrhage can lead to **acute** **blindness** - If repeated; leads to **fibrosis** & **scarring** - Can lead to: **tractional retinal detachment:** when scar tissue or other tissue grows on your retina and **pulls it away from the layer underneath**

Question 54

Which pathology is depicted? [1]

Answer 54

**Diabetic maculopathy:** hard exudates near to the macula

Question 55

What is depicted in this image? [1]

Answer 55

**Proliferative diabetic retinopathy:** extensive vitreous haemorrhage obscuring most of fundus (white circle)}

Question 56

What is the arrow pointing to? [1]

Answer 56

Cotton wool spot

Question 57

What is depicted in this image? [1]

Answer 57

**Non-proliferative diabetic retinopathy:** blot haemorrhage (white circle)}

Question 58

Describe what is happening in this image [1]

Answer 58

**Proliferative diabetic retinopathy:** **NVD** new vessels on the optic disc

Question 59

What is the management of diabetic retinopathy? [5]

Answer 59

**Laser photocoagulation** **Anti-VEGF medications** such as **ranibizumab, bevacizumab & Aflibercept** **Vitreoretinal surgery** (keyhole surgery on the eye) may be required in severe disease or a vitrectomy may be necessary to clear severe vitreous hemorrhage or to relieve tractional retinal detachment. Corticosteroids (**triamcinolone**, **dexamethasone implant**) can also be used, particularly in refractory DME. **Pan-retinal photocoagulation (PRP)**: laser used to make small burns evenly across the peripheral retina - should make blood vessels shrink and dissapear

Question 60

Name this sign [1] and disease [1] that is a complication of diabetes

Answer 60

**Prayer sign; diabetic cheiroarthropathy**

Question 61

The following term describes which sign of diabetic retinopathy *Damaged vessels may rupture and leak blood.* Venous beading Cotton wool spots Hard exudates Dot and blot haemorrhages Microaneurysms

Answer 61

The following term describes which sign of diabetic retinopathy *Damaged vessels may rupture and leak blood.* Venous beading Cotton wool spots Hard exudates **Dot and blot haemorrhages** Microaneurysms

Question 62

The following term describes which sign of diabetic retinopathy *transient, small, whitish opacities with feathery edges located within the superficial retina and represent microinfarctions of small retinal arteriole* Venous beading Cotton wool spots Hard exudates Dot and blot haemorrhages Microaneurysms

Answer 62

The following term describes which sign of diabetic retinopathy *transient, small, whitish opacities with feathery edges located within the superficial retina and represent microinfarctions of small retinal arteriole* Venous beading **Cotton wool spots** Hard exudates Dot and blot haemorrhages Microaneurysms

Question 63

The following term describes which sign of diabetic retinopathy *Deposits of lipids that have leaked onto the retina through damaged vessels.* Venous beading Cotton wool spots Hard exudates Dot and blot haemorrhages Microaneurysms

Answer 63

The following term describes which sign of diabetic retinopathy *Deposits of lipids that have leaked onto the retina through damaged vessels.* Venous beading Cotton wool spots **Hard exudates** Dot and blot haemorrhages Microaneurysms

Question 64

The following term describes which sign of diabetic retinopathy *“Out-pouching” results from weakened capillary walls. The earliest visible clinical sign of diabetic retinopathy.* Venous beading Cotton wool spots Hard exudates Dot and blot haemorrhages Microaneurysms

Answer 64

The following term describes which sign of diabetic retinopathy *“Out-pouching” results from weakened capillary walls. The earliest visible clinical sign of diabetic retinopathy.* Venous beading Cotton wool spots Hard exudates Dot and blot haemorrhages **Microaneurysms**

Question 65

What is the most common cause of visual loss in patients with diabetes? [1] Describe this [1]

Answer 65

**Diabetic macular oedema (DMO)** DMO is the commonest cause of visual loss in patients with diabetes **DMO is characterised by oedematous changes in or around the macula**. As the macula is responsible for central vision, affected patients tend to complain of blurred vision when reading or difficulty recognising faces in front of them. DMO is the commonest cause of visual loss in patients with diabetes.9

Question 66

DMO can be subcategorised into three categories. Describe them [3]

Answer 66

**Focal/diffuse macular oedema:** * the fluid that escapes from damaged vessels can be well-circumscribed (focal) or more widespread and poorly demarcated in nature (diffuse). **Ischaemic maculopathy**: - patients will be symptomatic with defects in visual acuity due to ischaemia at the site of the macula. These areas are best visualised with fluorescein angiography. **Clinically significant macular oedema (CSMO):** - CSMO describes significant changes associated with retinopathy, such as hard exudates and retinal thickening, found within a certain distance to the fovea or greater than a certain size.

Question 67

What is the name of this treatment for diabetic retinopathy? [1]

Answer 67

Pan-retinal photocoagulation (PRP)

Question 68

Name a complication of diabetic retinopathy [1]

Answer 68

Diabetic retinopathy is one of several causes of **neovascular glaucoma**: a type of secondary glaucoma. Neovascularization can occur within the iris and its trabecular meshwork (rubeosis) causing a narrowing and closure of the drainage angle and therefore increased intraocular pressure.

Question 69

Name a complication of diabetic retinopathy [1]

Answer 69

Diabetic retinopathy is one of several causes of **neovascular glaucoma**: a type of secondary glaucoma. Neovascularization can occur within the iris and its trabecular meshwork (rubeosis) causing a narrowing and closure of the drainage angle and therefore increased intraocular pressure.

Question 70

What level of diabetic retinopathy does it suggest? [1]

Answer 70

**New vessels on disc** - Proliferative DR

Question 71

What level of diabetic retinopathy does it suggest? [1]

Answer 71

**Microaneursym** - Non-proliferative DR

Question 72

What level of diabetic retinopathy does it suggest? [1]

Answer 72

**New vessels everywhere**: - PDR

Question 73

What level of diabetic retinopathy does it suggest? [1]

Answer 73

Dot & Blot haemorrhages - NPDR

Question 74

Answer 74

**Diabetic maculopathy**

Question 75

Describe the 4 stages of hypertensive retinopathy [4]

Answer 75

Question 76

Answer 76

Question 77

Answer 77

Question 78

Answer 78

Question 79

Answer 79

Grade 4

Question 80

Describe the difference in findings between central retinal artery occlusion and central retinal vein occlusion [+]

Answer 80