Visual Loss and Blindness Flashcards by Aliya Hussain

2 types of visual loss?

Sudden visual loss (inc. sudden transient visual loss)

Gradual visual loss

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Main causes of sudden visual loss?

Vascular aetiology
Retinal detachment
Age-related macular degeneration (ARMD - wet-type
Closed-angle glaucoma
Optic neuritis
Stroke

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Arterial supply to the eye?

Major blood supply to eye:
• Various branches of ophthalmic artery (branch of the ICA)

Branches include:
• Central retinal artery
• Posterior ciliary arteries

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Blood supply to the layers of the retina?

Inner 2/3rds supplied by the central retinal artery

Outer 1/3rd supplied by the posterior ciliary artery

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Vascular causes of sudden visual loss?

OCCLUSION of:
• Retinal circulation (CRAO or BRAO)
• Optic nerve head (AKA optic disc) circulation

HAEMORRHAGE from:
• Abnormal blood vessels, e.g: diabetes, wet ARMD
• Retinal tear

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Symptoms of central retinal artery occlusion (CRAO)?

SUDDEN, profound visual loss that is PAINLESS

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Examination findings with CRAO?

RAPD (relative afferent pupil defect)

Pale, oedematous retina with thread-like retinal vessels

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Causes of CRAO?

It is a type of stroke and causes include:
• Carotid artery disease (atherosclerotic) is the main cause
• Emboli from the heart (unusual)

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Ophthalmic management of CRAO?

If it presents within 24 hours, try ocular massage (which attempts to dislodge the embolus to an area further down the vascular tree)

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Vascular management of CRAO?

Vascular management:
• Establish source of the embolus (Ix with a carotid doppler)
• Assess and manage risk factors

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Examination signs with BRAO?

Only a small area of the retina is pale, e.g: if the retina is pale inferiorly, they are likely to have a superior visual field defect

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Symptoms of amaurosis fugax (AKA transient CRAO)

Transient, painless visual loss (like a curtain coming down)

It lasts only 5 minutes and then their is full recovery

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Examination signs with amaurosis fugax?

Usually, nothing abnormal is seen

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Mx of amaurosis fugax?

Immediate referral to a TIA clinic

Aspirin

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Other causes of transient visual loss?

Migraine (although the visual loss typically follows a headache)

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Systemic causes of central retinal vein occlusion (CRVO)?

Virchow’s triad:
• Atherosclerosis (change in vessel walls)
• Hypertension (change in blood flow)
• Hyperviscosity (change in blood constituents)

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Ocular causes of CRVO?

Raised intra-ocular pressure (with venous stasis)

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Symptoms of CRVO?

Sudden visual loss

Moderate to severe visual loss

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Examination signs of CRVO?

Retinal haemorrhages

Dilated tortuous veins

Disc swelling and macular swelling

Cotton-wool spots (small infarcts of the nerve fibre layer)

THERE IS NO PALLOR

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Complication of CRVO?

Ischaemic eye grows new blood vessels, which are fragile and prone to bleeding

Can cause, e.g: a vitreous haemorrhage

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Treatment of CRVO?

Treat the systemic or ocular cause, e.g: hypertension, diabetes, glaucoma

Anti-VEGF (vascular endothelial growth factor) can stop budding of new vessels

Monitoring for complications (new vessels require laser treatment to avoid issues like a vitreous haemorrhage)

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Summarise the cause and locations for occlusion of the retinal circulation?

Arterial (embolic):
• Central retinal artery
• Branch retinal artery

Venous (stasis):
• Central retinal vein
• Branch retinal vein

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Colour of the retina in arterial vs vein occlusion?

Pale in arterial occlusion

Dark in venous occlusion

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Describe occlusion of the optic nerve head circulation

AKA ischaemic optic neuropathy

The posterior ciliary arteries (PCA) become occluded, resulting in infarction of the optic nerve head

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Types of ischaemic optic neuropathy (ION)?

Arteritis (50%) - inflammation (Giant Cell Arteritis) Non-arteritis (50%) - atherosclerosis

Symptoms of ION?

Both types cause SUDDEN, PROFOUND visual loss with a SWOLLEN DISC

Pathogenesis of GCA?

Inflammation of medium-large sized arteries (multinucleate giant cells) Lumina of the posterior ciliary arteries become occluded and there is ischaemia of the optic head, leading to visual loss

Examination signs of ION?

Pale, swollen optic disc

Visual symptoms of GCA?

Amaurosis fugax SUDDEN, profound visual loss and irreversible blindness Diagnosis and immediate treatment can prevent bilateral visual loss (as there is a risk of sudden complete blindness in the second eye)

Other symptoms of GCA (temporal arteritis)?

Temporal headache Jaw claudication Scalp tenderness (combing hair is painful) and tender, enlarged scalp arteries Malaise

Ix for GCA?

Very high inflammatory markers Temporal artery biopsy (skip lesions)

Where does haemorrhage often occur?

Into the vitreous cavity (AKA vitreous haemorrhage)

How does haemorrhage occur?

From abnormal vessels - assoc. with retinal ischaemia and new vessel formation, e.g: • After retinal vein occlusion • Diabetic retinopathy From normal retinal vessel - usually assoc. with a retinal tear

Symptoms of vitreous haemorrhage?

Loss of vision Floaters

Examination signs of vitreous haemorrhage?

Loss of red reflex Fundoscopy may show the haemorrhage

Mx of vitreous haemorrhage?

Identify the cause; often, it resolves physiologically For non-resolving cases, a vitrectomy can be done

Symptoms of retinal detachment?

Painless loss of vision Sudden onset of flashes and/or floaters (due to mechanical separation of the sensory retina from the retinal pigment epithelium)

Examination signs of retinal detachment?

May have RAPD Ophthalmoscopy may show a tear

Mx of retinal detachment?

Usually surgical

Presentation of retinal detachment?

Depends on site, e.g: an inferior tear can cause a superior visual defect

Types of age-related macular degeneration (ARMD)?

Dry (causes a GRADUAL reduction in vision) Wet (causes a SUDDEN reduction in vision)

Pathology of wet ARMD?

New blood vessels grow under the retina; leakage causes build-up of fluid/blood, which separates the layers and leads to scarring

Symptoms of wet ARMD?

Rapid CENTRAL vision loss - cannot see black dot in the centre of the Amsler grid Distortion (metamorphosis) -straight lines become wavy when looking at the Amsler grid

Examination signs of wet ARMD?

Haemorrhage/exudate on ophthalmoscopy

Treatment of wet ARMD?

Anti-VEGF treatment injected into the vitreous cavity; prevents new blood vessel growth by binding to VEGF Previously used laser and photodynamic therapy

Presentation of bilateral visual loss?

Usually bilateral and often asymmetrical (worse in one eye) May present either: • Early with reduced visual acuity • Late with decreased visual field

Mnemonic for the causes of gradual visual loss?

CARDIGAN Cataract Age-related macular degeneration (dry type) Refractive erroe Diabetic retinopathy Inherited diseases, e.g: retinitis pigmentosa Glaucoma Access (to eye clinic) that is Non-urgent

What is a cataract?

Cloudiness of the lens that has many different causes and there are many different types

Causes of cataract?

* Age-related * Congenital (due to an intra-uterine infection; must check red reflex in neonates) * Traumatic * Metabolic (diabetes, etc) * Drug-induced (e.g: steroids)

Types of cataracts?

Nuclear cataract (rainbow appearance); impaired distance vision Posterior subcapsular cataract; profoundly affects vision Polychromatic cataract (Christmas tree cataract) Congenital cataract ...others

Treatment of cataract?

If the patient is symptomatic, surgical removal with intra-ocular lens implant

Symptoms of dry ARMD?

Gradual decline in vision Central vision is 'missing' (scotoma)

Examination signs of dry ARMD?

Drusen (build up of waste products below the RPE) Atrophic patches of retina

Treatment of dry ARMD?

No cure Supportive treatment with low vision aids, e.g: magnifiers

Types of refractive errors?

* Myopia (short-sighted) * Hypermetropia (long- sighted) * Astigmatism (usually irregular corneal curvature) * Presbyopia (loss of accommodation with aging)

Pathogenesis of glaucoma?

Unclear aetiology but raised IOP may be implicated It causes progressive optic neuropathy and visual loss

Types of glaucoma?

Open-angle (irido-corneal angle is open and as wide as usual) Closed-angle (narrowed or closed irido-corneal angle)

Presentation of closed-angle glaucoma?

``` May be acute (ophthalmic emergency) with: • Painful, red eye • Visual loss • Headache • Nausea and vomiting ```

Treatment of glaucoma?

Lower IOP with: | • Drops/oral mediation

Presentation of open-angle glaucoma?

Often asymptomatic and an incidental finding by the optician

Examination signs of open-angle glaucoma?

Cupped disc Visual field defect May/may not have a high IOP

Treatment of open-angle glaucoma?

Preserve vision by lowering IOP (improve drainage or reduce production) • Eye drops • Laser • Surgery (trabeculectomy) Regular monitoring

Visual Loss and Blindness Flashcards

(62 cards)