Retinal Vasculature Flashcards by Bradley Brown

What are some common leakage/depositions defects in the retina?

• Haemorrhages in and around the retina
• Oedema
• Exudates
• Drusen
• Cotton wool spots

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Types of haemorrhage:

• Retinal haemorrhages
- Flame shaped haemorrhages
- Dot-blot haemorrhages
• Sub-retinal haemorrhages
• Pre-retinal haemorrhages
- Subhyaloid haemorrhages
- Vitreous hemorrhages

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Retinal haemorrhages:

• Flame shaped haemorrhages
- from superficial pre-capillary arterioles
- in NFL
• Dot-blot haemorrhages
- from venous end of capillaries
- in middle retinal layers

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Sub retinal haemorrhages: describe

• Dark colour
• Retinal vessels clearly visible above
• Blood can spread in this area so these harmorrhages can have an arbitrary shape
• Can be associated with an RPE detachment

• Causes include:
- wet ARMD (by far most common)
- choroidal tumors
- trauma

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Sub-hyaloid haemorrhages: describe

• Level of subhyaloid space between posterior vitreous face and retina OR under internal limiting membrane

• May get localised vitreous detachment
• Characteristically have a boat-shaped (horizontal blood level) appearance

• Obscures underlying retina

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Vitreous Haemorrhages: Describe

• Spread of subhyaloid haemorrhage into vitreous itself
• Often blurry appearance
• Obscures underlying retina

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Vitreous Haemorrhages: causes

• Abnormal blood vessels
- Don’t have endothelial tight junctions, predisposing them to spontaneous bleeding
• Rupture of normal blood vessels
- Something pulling on blood vessel and causes it to rupture
- Trauma

• Blood from adjacent source
- Haemorrhages from retinal haemorrhages, tumours, wet ARMD can extend into vitreous

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Oedema: Describe

• Diffuse: caused by extensive leakage

• Localised: focal leakage

• Between OPL and INL, may later involve IPL and NFL

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Exudates: Describe

• Chronic localised oedema
• Located at junction of normal and oedematous tissue
• Lipoprotein and macrophages
• Mainly in OPL
• Get spontaneously absorbed

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Drusen: Describe

• RPE hyperpigmentation

• Deposition of Lipofuscin between Bruch’s membrane and the RE; metabolically active cells
- Deficient metabolism of the photoreceptor outer segments by the RE

• Increase in number and size causing damage to photoreceptors reduction in vision

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Cotton wool spots: Describe

• Accumulation of neuronal debris in NFL
• Disruption of axial flow of neurons

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Hypertensive retinopathy: symptoms

• Most often patient is asymptomatic
• Blurred/distorted vision if at later stage and it affects the macula

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Hypertensive retinopathy: signs
(Venous/arterial)

• Venous changes:
- dilation
- tortuosity

• Arterial changes:
- AV nipping
- generalised narrowing
- localised narrowing
- copper wiring
- silver-wiring

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Hypertensive retinopathy: Signs

• Retinal haemorrhages (dot blot and flame)
• Hard exudates, macular star
• Cotton wool spots
• Disc swelling

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Hypertensive retinopathy: Management

• Get BP checked
• If severe send to ophthalmologist

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Retinal artery occlusion: Describe and types

• Most commonly caused by atherosclerosis related embolism and thrombosis
• Causes sudden, profound, painless, loss of vision affecting the retinal area that the artery supplies

Types:
• Amaurosis fugax
• Branch retinal artery occlusion
• Central retinal artery occlusion
• Cilioretinal artery occlusion

Amaurosis fugax: Symptoms

• Transient monocular loss of vision due to an embolus
• ‘Curtain over vision’
• Complete or incomplete loss of vision
• Typically lasts a few minutes

Amaurosis fugax: Signs

• Usually no retinal signs evident

Retinal artery occlusion: Signs

• Fundus:
- Attenuation of arteries
- Cloudy white oedematous retina in affected are
- Visible emboli
- CRAO: cherry red spot which disappears gradually over days/weeks

• VA variable, dependent upon location of occlusion, e.g. CRAO VA severely reduced, if branch not affecting macula VA could be ok

• RAPD often present in branch, profound in CRAO

Retinal artery occlusion: management

• Emergency referral to hospital and 1st aid measures at hospital if within 24-48hrs of occlusion
• Otherwise urgent referral to hospital

Describe Retinal Vein occlusion:

• Typically, atherosclerotic hardening of an artery compresses the vein at the arteriovenous crossing point where they share a sheath

Retinal Vein occlusion: Signs

• Increased arteriolar light reflex (copper wiring - silver wiring)
• tortuosity
• AV nipping

Retinal Vein occlusion: Predisposing factors

• Age
• HBP
• High cholesterol
• Diabetes
• Oral contraceptive o Increased IOP
• Smoking

Retinal Vein occlusion: Types

• Branch retinal vein occlusion
• Central retinal vein occlusion
- Impending (partial; mild non-ischaemic)
- Non-ischaemic
- Ischaemic
• Hemi-retinal (may be ischaemic or non-ischaemic as above)

Retinal Vein occlusion: Symptoms

• Sudden painless onset of reduced/blurred vision

Retinal Vein occlusion: Signs (Fundus; Acute)

• Dilation and tortuosity of affected venous segment • Flame-shaped and dot blot haemorrhages in retinal area drained by the vein • Cotton wool spots and disc swelling if CRVO • Resolve within 6-12 months

Retinal Vein occlusion: Signs (Fundus; Long term)

• Collateral vessels (aka AV shunts, aka optociliary shunts) after weeks-months (good prognosis due to improved blood supply and reduction in possibility of neovascularisation) • Chronic macular oedema • Neovascularisation: retinal and in iris after approx 2-4months

Retinal Vein occlusion: Signs (VA)

• VA is dependent on severity/location - e.g. CF or less if ischaemic CRVO, 6/12 or could be better if branch or non-ischaemic • RAPD is dependent on severity e.g. CRVO: profound RAPD, non-ischaemic or branch: mild/absent

Retinal Vein occlusion: Signs (Management)

• Urgent referral to ophthalmologist • Detection and management of associated systemic disease • Ophthalmological follow-up: - CRVO: Monthly follow-up for 1st 6/12, gonioscopy to check angles - BRVO: Follow-up 6-12 weeks to check resolution - Treat macular oedema or neovascularisation

Diabetic retinopathy: Symptoms

• Often asymptomatic (unless it affects the macula) • Blurred/distorted vision • Sudden onset reduced vision

Diabetic retinopathy: Investigations

• VA o Retinal examination • Visual fields (? if see something?) • IOP (? for a baseline?) • Slit lamp

Diabetic retinopathy: Signs

• Caused by leakage: - Microaneurysms, Retinal haemorrhages (dot-blot and flame-shaped), Oedema, Hard exudates • Signs caused by retinal ischaemia: - Cotton wool spots, IRMA • Venous changes: dilation, tortuosity, looping, beading, sausage-like segmentation • Arterial changes: narrowing (esp periphery), silver-wiring • Signs caused by hypoxia: new blood vessels

Diabetic retinopathy: Management

• Monitor during milder stages (either optometrist or vision screening or by ophthalmologist if a bit more advanced) • Laser surgery to stop growth of blood vessels

What are the types of abnormal blood vessels at level of retina:

• IRMA aka A-V shunts - Dilated capillaries - collateral vessels (maintain blood flow to a structure when main blood supply blocked) - telangiectasis • New blood vessels

Intra-Retinal Microvascular Abnormalities (IRM)

• A-V shunts running between arterioles and venules • New vessels or dilated capillaries?? • IRMA tend not to leak on fluorescein angiography therefore more likely to be dilated capillaries

New blood vessels: Describe

• New vessels at the disc (NVD) • New vessels elsewhere (NVE) • New vessels in the iris (NVI) • New vessels: - Cross major blood vessels - Leak in fluorescein angiography (FA)

How can Blood vessels change:

• Microaneurysms • Venous changes: dilation, tortuosity, looping, beading, sausage-like segmentation • Arterial changes: narrowing (esp periphery), silver-wiring • AN nipping

Micro-aneurysms: Describe

• dilation of capillary wall • endothelial cell proliferation