Visual Loss Flashcards by Martha Innes

What are the causes of sudden visual loss?

Wet age-related macular degeneration (ARMD)
Central retinal artery/vein occlusion
Virtual haemorrhage
Closed angle glaucoma
Retinal detachment

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What artery is the main blood supply to the eye?

Ophthalmic artery

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What are the main branches of the ophthalmic artery?

Central retinal artery

Posterior ciliary arteries

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What are the vascular causes of sudden visual loss?

Occlusion of retinal circulation or optic nerve circulation

Haemorrhage form normal (bridging a retinal tear) or abnormal (DM, wet AMD) blood vessels

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What are the causes of central retinal artery occlusion (CRAO)?

Carotid artery disease
Emboli from atheroma
Emboli from diseased heart valves
Giant cell arteritis

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What part of the retina does the central retinal artery supply?

Inner 2/3rds

outer 1/3rd supplied by choroid

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What are the symptoms of CRAO?

Sudden, usually painless, visual loss

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What are the clinical signs of CRAO?

Relative afferent papillary defect (RAPD)

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What signs of CRAO are seen on ophthalmoscopy?

Pale, oedematous retina
Cerry red spot at fovea
Narrow, thread-like vessels

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Why is there a pale retina but cherry red spot in CRAO?

Oedema within the retina occurs which obscures the choroid (which usually gives the red colour) but the retina is very thin at the fovea so vasculature shows through

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What are two other types of retinal artery occlusion other than CRAO?

Branch retinal artery occlusion
Amaurosis fugax (transient CRAO lastin 5 mins or so_)

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What factors is central retinal vein occlusion (CRVO) associated with?

Endothelial damage
Hypercoagulable state
Abnormal blood flow

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What is the pathogenesis of CRVO?

Often the retinal artery crosses over the vein
If the artery becomes atherosclerotic it becomes a rigid structure, which can limping upon the vein
This can lead to haemodynamic disturbance, endothelial damage and thrombus formation

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What are the risk factors for CRVO?

Increasing age
Hypertension and CVD
Diabetes
Glaucoma
Blood dycrasias and vasculitis

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What are the symptoms of CRVO?

Sudden, usually painless, visual loss

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What signs of CRVO are seen on ophthalmoscopy?

Retinal haemorrhages
Dilated, tortuous veins
Disc swelling and macular swelling
Cotton wool spots

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What is ischaemic optic neuropathy?

Occlusion of optic nerve head circulation (posterior ciliary arteries)

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What are the symptoms of ischaemic optic neuropathy?

Sudden (or stuttering) visual loss
Typically the lower half of the visual field
Usually painless

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What are the signs of ischameic optic neuropathy on ophthalmoscopy?

Swollen optic nerve
Later - optic atrophy
Bilateral later in 1/3rd of cases

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What needs to be a consideration in ischaemic optic neuropathy?

Giant cell arteritis

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What is giant cell arteritis?

An inflammatory condition where posterior ciliary arteries become inflamed and the lumen becomes occluded
This affects other arteries, including temporal arteries

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What are the symptoms of giant cell arteritis?

Headache
Scalp tenderness
Enlarged temporal arteries

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How can diabetes or retinal vein occlusion cause vitreous haemorrhage?

These cause retinal ischaemia which causes abnormal new vessels to form
These are very fragile and bleed easily

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How can vitreous haemorrhage occur from normal vessels?

When a vessel bridges a retinal tear it can break and haemorrhage

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What are the symptoms of vitreous haemorrhage?

Sudden loss of vision | Floaters

What are the clinical features of vitreous haemorrhage?

Loss of red reflex

What signs of vitreous haemorrhage can be seen on ophthalmoscopy?

May see a haemorrhage

What are the symptoms of retinal detachment?

Painless loss of vision | Sudden onset of flashes/floaters

What causes flashes and floaters?

Mechanical separation of sensory retina from retinal pigment epithelium

What are the clinical signs of retinal detachment?

May have RAPD

What signs of retinal detachment can be seen on ophthalmoscopy?

May see a tear

What is rhegmatogenous retinal detachment?

Where a tear in the retina causes the rest of the retina to peel away from retinal pigment epithelium

What is the commonest cause of blindness in the UK?

Age related macular degeneration (ARMD)

What is the cause of ARMD?

Unknown

What are the risk factors for ARMD?

Increasing age Smoking Positive family history Poor nutrition

What are the two types of ARMD, and what is the main difference?

Wet - sudden loss of vision | Dry - gradual loss of vision

What is the physiology of wet ARMD?

New abnormal blood vessels grow under the retina in the region of the macula Leakage causes buildup of fluid/blood and eventually scarring

What are the symptoms of wet ARMD?

Rapid central visual loss | Distortion of vision (metamorphopsia)

What signs of wet ARMD can be seen on ophthalmoscopy?

Haemorrhage | Hard exudates

What is the treatment for wet ARMD?

Anti-VEGF

What is glaucoma?

Progressive optic neuropathy (probably) caused by increased intraocular pressure

What are the two types of glaucoma?

Open angle and closed angle

What is the pathogenesis of closed angle glaucoma?

Resistance to aqueous fluid passing out through the iris/lens channel causes fluid to build up, which starts to push the iris forward This closes the angle between the iris and the cornea, blocking the drainage of fluid through trabecular meshwork - pressure increases further

What are the symptoms of closed angle glaucoma?

Very painful Sudden visual loss Headache Nausea, vomiting

What are the clinical signs of closed angle glaucoma?

Red eye Cloudy cornea Mid-dilated pupil

What is the treatment for closed angle glaucoma?

Lower intraocular pressure with drops/oral medication to prevent the patient from going blind Surgery can be done if medication not sufficient

What are the causes of gradual visual loss?

``` ARMD Refractive error Cataract Diabetes Open angle glaucoma ```

What are cataracts?

Abnormal changes in lens proteins that result in their chemical and structural alteration, leading to loss of transparency - clouding of the lens

What are the causes of cataracts?

Age-related Congenital Diabetes Drug induced (oral steroids)

What are the different types of cataracts?

Nuclear cataract Posterior sub-capsular cataract Christmas tree cataract Congenital cataract

What are the symptoms of cataracts?

Gradual visual loss (hazy/blurred)

What is the management for cataracts?

Surgical removal with intra-ocular lens implant if patient is symptomatic

What is dry ARMD?

Tiny build up of yellow-white lesions under the retina made of lipid and metabolic by-products from pigment epithelial cells Deposits build up and stop diffusion of nutrients from the choroid The retina overlying this area becomes thin and atopic and loses its function - visual loss

What are the symptoms of dry ARMD?

Gradual decline in vision | Central vision missing (scotoma)

What signs of dry ARMD can be seen on ophthalmoscopy?

Drusen - build up of waste products | Atrophic patches to the retina

What is the treatment for dry ARMD?

No cure | Low vision aids

What are the disorders of refractive error?

Myopia (short sighted) Hyperopia (long sighted) Astigmatism (irregular corneal curvature) Presbyopia (loss of accommodation with ageing)

What is the pathophysiology of open angle glaucoma?

The iriscorenal angle is open but there is blockage to drainage aqueous fluid through he trabecular meshwork which leads to raised IOP

What are the symptoms of open angle glaucoma?

Often none - discovered by optician | Visual field defect

What are the signs of open angle glaucoma on ophthalmoscopy?

High cup to disc ratio | May be haemorrhages

What is an arcuate field defect?

Nerve fibres travel horizontally from he fovea straight to the optic disc (papillomacular bundle) Ganglion cell's from outside that area have to arc around the papillomacular bundle in order to get to the disc (arcuate fibres) Field defects in glaucoma often correspond tot he anatomical patterns - field defect will curve around the macula