Retinal Vasculature Flashcards
What are some common leakage/depositions defects in the retina?
• Haemorrhages in and around the retina
• Oedema
• Exudates
• Drusen
• Cotton wool spots
Types of haemorrhage:
• Retinal haemorrhages
- Flame shaped haemorrhages
- Dot-blot haemorrhages
• Sub-retinal haemorrhages
• Pre-retinal haemorrhages
- Subhyaloid haemorrhages
- Vitreous hemorrhages
Retinal haemorrhages:
• Flame shaped haemorrhages
- from superficial pre-capillary arterioles
- in NFL
• Dot-blot haemorrhages
- from venous end of capillaries
- in middle retinal layers
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
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
Vitreous Haemorrhages: Describe
• Spread of subhyaloid haemorrhage into vitreous itself
• Often blurry appearance
• Obscures underlying retina
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
Oedema: Describe
• Diffuse: caused by extensive leakage
• Localised: focal leakage
• Between OPL and INL, may later involve IPL and NFL
Exudates: Describe
• Chronic localised oedema
• Located at junction of normal and oedematous tissue
• Lipoprotein and macrophages
• Mainly in OPL
• Get spontaneously absorbed
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
Cotton wool spots: Describe
• Accumulation of neuronal debris in NFL
• Disruption of axial flow of neurons
Hypertensive retinopathy: symptoms
• Most often patient is asymptomatic
• Blurred/distorted vision if at later stage and it affects the macula
Hypertensive retinopathy: signs
(Venous/arterial)
• Venous changes:
- dilation
- tortuosity
• Arterial changes:
- AV nipping
- generalised narrowing
- localised narrowing
- copper wiring
- silver-wiring
Hypertensive retinopathy: Signs
• Retinal haemorrhages (dot blot and flame)
• Hard exudates, macular star
• Cotton wool spots
• Disc swelling
Hypertensive retinopathy: Management
• Get BP checked
• If severe send to ophthalmologist
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
