Visual Loss and Blindness Flashcards
2 types of visual loss?
Sudden visual loss (inc. sudden transient visual loss)
Gradual visual loss
Main causes of sudden visual loss?
- Vascular aetiology
- Retinal detachment
- Age-related macular degeneration (ARMD - wet-type
- Closed-angle glaucoma
- Optic neuritis
- Stroke
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
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
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
Symptoms of central retinal artery occlusion (CRAO)?
SUDDEN, profound visual loss that is PAINLESS
Examination findings with CRAO?
RAPD (relative afferent pupil defect)
Pale, oedematous retina with thread-like retinal vessels
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)
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)
Vascular management of CRAO?
Vascular management:
• Establish source of the embolus (Ix with a carotid doppler)
• Assess and manage risk factors
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
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
Examination signs with amaurosis fugax?
Usually, nothing abnormal is seen
Mx of amaurosis fugax?
Immediate referral to a TIA clinic
Aspirin
Other causes of transient visual loss?
Migraine (although the visual loss typically follows a headache)
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)
Ocular causes of CRVO?
Raised intra-ocular pressure (with venous stasis)
Symptoms of CRVO?
Sudden visual loss
Moderate to severe visual loss
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
Complication of CRVO?
Ischaemic eye grows new blood vessels, which are fragile and prone to bleeding
Can cause, e.g: a vitreous haemorrhage
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)
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
Colour of the retina in arterial vs vein occlusion?
Pale in arterial occlusion
Dark in venous occlusion
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
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
