Visual Loss + Blindness Flashcards
Define swollen optic disc vs papilloedema
‘Swollen optic discs’ means disc swelling secondary to ANY cause
‘Papilloedema’ is a specific term meaning swollen optic discs secondary to raised intracranial pressure (ICP).
What should you suspect in bilateral optic disk swelling?
All patients with bilateral optic disc swelling should be suspected of having raised ICP due to a space occupying lesion (SOL) until proven otherwise.
Raised ICP is a medical emergency.
Give five things that CN II examination should include
- Visual acuity
- Pupil exam
- Visual field assessment
- Colour vision
Describe the pathophysiology of papilloedema
- Subarachnoid space (SAS) around optic nerve (ON) continuous with subarachnoid space surrounding the brain.
- When intracranial pressure increases, this is transmitted to the SAS then to the ON…..
- This causes interruption of axoplasmic flow and venous congestion = swollen discs.
Intracranial pressure is the sum of which three components?
- Brain – 80%
- Blood – 10%
- CSF – 10%
How does raised ICP kill?
With raised ICP, brain is squeezed through foramen magnum, brainstem compressed, patient stops breathing and dies.
Give one cardio investigation you should always do in a patient with raised ICP?
Blood pressure
What is the function of the choroid plexus?
A network of capillaries which filter blood to form CSF
25 yo female with 6 month history of headaches, BMI 40, VA 6/6 R & L.
Lumbar puncture showed raised CSF opening pressure.
Diagnosis?
- Mechanism of swelling?
Idiopathic intracranial hypertension
Various theories relating to
- Obstruction to CSF circulation
- Impaired CSF absorption
What happens if disc swelling of any cause becomes chronic?
Disc swelling subsides, discs become atrophic and pale.
Loss of visual function occurs and blindness may result.
Give six causes of sudden visual loss
- Vascular aetiology
- Retinal detachment
- Age related macular degeneration (ARMD) - wet type
- Closed angle glaucoma
- Optic neuritis
- Stroke
Which artery gives branches to supply the eye?
What is this artery a branch of?
Ophthalmic artery
Internal carotid artery
Name two arteries that the ophthalmic artery gives off
Central retinal artery
Posterior ciliary arteries either side
Describe the arterial blood supply to the retina
Inner 2/3 retina supplied by central retinal artery branches
Outer 1/3 of retina supplied by posterior ciliary arteries
Give four vascular aetiologies of sudden visual loss
Occlusion of - Retinal circulation - Optic nerve head circulation Haemorrhage from - Abnormal blood vessels (e.g. diabetes, wet ARMD) - Retinal tear
Describe the symptoms of central retinal artery occlusion and the appearance on funsoscopy
- Sudden visual loss
- Profound (CF or less- remember CRA is ‘end artery’)
- Painless
On fundoscopy the retina looks very pale - the orange bit is actually healthy retina
Also thread like retinal vessels
What is myosis?
Constriction of pupils
What happens to the pupil in central retinal artery occlusion?
Relative afferent pupil defect (RAPD)
As you swing light from one side to the other, the abnormal pupil dilates due to less contriction of the sphincter pupillae
Give two general causes of CRAO
- Carotid artery disease
2. Emboli from the heart (unusual)
Name two variants of central retinal vein occlusion
- Branch retinal artery occlusion
2. Amaurosis fugax
Describe the appearance of superior retinal artery occlusion on fundoscopy
What will visual loss be like?
Where will the visual field defect be?
Paler bit superior to macula – can see that the artery looks thinner compared to the vein.
Visual loss may not be as profound.
Will have a visual field defect at the bottom of their vision.
What is the other name for Transient CRAO?
What happens in the condition?
What is the characteristic symptoms in this condition?
Amaurosis fugax
Central retinal artery is blocked and then becomes released
Patients describe a curtain/dark shutter coming down – very characteristic for this condition.
This lasts~5mins with full recovery
Which clinic should patients with transient CRAO be referred to?
TIA - do this immediately
Also give aspirin if no contraindications
Name another cause of transient visual loss
What other main symptom does this condition have?
Migraine – visual loss usually followed by headache. This is an important differential to keep in mind when considering amaurosis fugax.
Give four causes of CRVO
Atherosclerosis
Hypertension
Hyperviscosity
Raised IOP (venous stasis)
Give some symptoms and signs of CRVO
Treatment?
Sudden visual loss - moderate to severe Retinal haemorrhages Dilated tortuous veins Disc and macular swelling Looks like a "horrific pizza"
Treatment of CRVO?
- Based on cause
- Monitor: may develop complications due to development of new vessels (laser treatment may be required to avoid complications from these vessels e.g. vitreous haemorrhage)
- anti-VGEF - chemicals which you inject into the vitreous cavity to stop new vessels budding
What other type of vein occlusion should you keep a look out for?
Branch veins occlusion - only a sector of the retina is affected, but similar things are observed in the affected area - haemorrhage, cotton wool spots.
What is ischaemic optic neuropathy? Which arteries become occluded? What are the two types? What symptom do both types cause? How does the disc appear?
Occlusion of optic nerve head circulation
Posterior ciliary arteries (PCA) become occluded, resulting in infarction of the optic nerve head
1. Arteritic 50% - inflammation (GCA) – in tiny vessels such that is blocks off the artery
2. Non-arteritic 50% - atherosclerosis
Both cause sudden, profound visual loss with swollen disc.
Disc appears pale and swollen
Describe the pathogenesis of arteritic ION
- Giant cell arteritis (GCA)
- Medium to large sized arteries inflamed (multinucleate giant cells)
- Lumen of artery becomes occluded (posterior ciliary arteries)
- Visual loss from ischaemia of optic nerve head
- Image opposite is temporal artery – grossly thickened with inflammation + v narrow lumen
What symptoms does arteritic ION caused by GCA cause?
How can you prevent visual loss in the other eye?
- Sudden visual loss
- Profound (CF – NPoL)
- Irreversible blindness
- Important as diagnosis and immediate treatment may prevent bilateral visual loss
Immediate high dose systemic steroid may prevent other eye going blind.
Describe the symptoms of GCA
- Headache (usually temporal)
- Jaw claudication
- Scalp tenderness (painful to comb hair)
- Tender/enlarged scalp arteries
- Amaurosis fugax
- Malaise
- Very High ESR , PV and CRP
- Temporal artery biopsy may help diagnosis
Where in the eye does haemorrhage commonly occur?
Where does the bleeding come from?
Vitreous cavity - “vitreous haemorrhage”
Bleeding occurs from abnormal vessels - associated with retinal ischaemia and new vessel formation e.g. after retinal vein occlusion or diabetic retinopathy.
Bleeding occurs from normal retinal vessels - usually associated with a retinal tear.
Vitreous haemorrhage
- Symptoms?
- Signs?
- Management?
Symptoms - Loss of vision - ‘Floaters’ Signs - Loss of red reflex - May see haemorrhage on fundoscopy Management - Identify cause - Vitrectomy for non-resolving cases
Retinal detachment
- Symptoms?
- Signs?
- Management?
Symptoms - Painless loss of vision - Sudden onset of flashes/floaters (mechanical separation of sensory retina from retinal pigment epithelium) – pigment cells are liberated and dispersed into vitreous cavity Signs - May have RAPD - May see tear on ophthalmoscopy Management is usually surgical
What are the two types of age related macular degeneration?
- Dry (gradual reduction in vision)
- Wet (sudden reduction in vision)
What are the three layers at the back of the eye?
- Retinal layer
- Retinal pigment epithelium - has a variety of functions which keep the retinal healthy
- Choroid plexus - rich vascular network from posterior ciliary arteries
What is the pathology in wet macular degeneration?
Symptoms + signs?
Treatment?
Basically New blood vessels grow under retina – leakage causes build up of fluid/blood and eventually scarring.
- Rapid central visual loss
- Distortion (metamorphopsia) or patches of visual loss
- Haemorrhage/exudate
Anti-VEGF treatment – injected into vitreous cavity. Stops new blood vessels growing by binding to VEGF (vascular endothelial growth factor).
What is the pnemonic for gradual loss of vision?
CARDIGAN
- Cataract
- Age related macular degeneration (dry type)
- Refractive error
- Diabetic retinopathy (covered in other lecture)
- Inherited diseases e.g. retinitis pigmentosa
- Glaucoma
Access (to eye clinic) Non-urgent
Management of cataract?
Management is surgical removal with intra-ocular lens implant if patient is symptomatic. Two small surgical incisions – put in a vibrating thing which mushes up the cataract and sucks it out.
Dry age related macular degeneration
- Pathology?
- Aetiology?
- Symptoms?
- Signs?
- Treatment?
Photoreceptors have constant turnover – waste products build up and form Drusen (white dots) – causes pigment epithelial cells to be lifted off the choroid -> retina becomes atrophic and thinned.
Multifactorial condition – age, genetics, UV exposure, dietary things.
- Gradual decline in vision
- Central vision ‘missing’ (scotoma)
- Drusen – build up of waste products below RPE
- Atrophic patches of retina
No cure – treatment is supportive with low vision aids e.g. magnifiers – shown opposite.
What is the defining feature in glaucoma?
Progressive optic neuropathy
Describe the symptoms and treatment of closed angle glaucoma
- May be acute (ophthalmic emergency)
- Patient presents with painful, red eye/visual loss/headache/nausea/vomiting
- Need to lower IOP with drops/oral medication to prevent patient going blind
- Emergency
Closed angle glaucoma
- Symptoms?
- Signs?
- Treatment?
Symptoms - Often NONE - Optician may discover it Signs - Cupped disc - Visual field defect - May/may not have high IOP Treatment – aim to preserve vision (by lowering IOP) with eye drops /laser/surgery. Patients need regular monitoring in eye clinic.
