Vascular and Neuro-Opthalmic Disease Flashcards
Cause of retinal artery occlusions
Thromboembolism - from atherosclerosis
Arteritis (for central retinal artery occlusion)
What is central retinal artery occlusion
Occlusion of the central retinal artery causing infarction of inner 2/3 of retina and vision loss
What structure supplies the outer 1/3 of retina
Choroid
What arteritis can cause central retinal artery occlusion
Giant cell arteritis
Symptoms of central retinal artery occlusion
Sudden, painless severe loss of vision
Unilateral
Signs of central retinal artery occlusion
Relative afferent pupil defect (RAPD)
Thread like arteries
Retina becomes pale and oedematous
Cherry red spot at fovea
What is relative afferent pupil defect
When one of the eyes responds differently to light
What is the normal pupil response to light
When light is shone on one eye, the pupil should constrict
The other eye should simultaneously constrict as well due to consensual light reflex
When the light is removed, both should dilate at the same time
How is relative afferent pupil defect tested
Swinging light test
- Shine the light onto one eye then wait about 3 sec then switch to the other eye
- When shone to the affected one - the affected pupil dilates more instead of constrict / the affected one constricts less than the affected one
Management of central retinal artery occlusion
Immediate referral to stroke clinic
Identify and treat underlying cause
What is branch retinal artery occlusion
When one of the branches of central retinal artery becomes occluded -> ischaemia to the area the branch supplies
Symptoms of branch retinal artery occlusion
Acute, painless visual impairment
Unilateral
Severity of visual loss depends on which area is affected
Signs of branch retinal artery occlusion
Absence of perfusion (shown as white plaques on fundoscopy)
Management of branch retinal artery occlusion
Refer to stroke clinic
What is amaurosis fugax
Transient central retinal artery occlusion
Amaurosis fugax is seen in
Giant cell arteritis
Symptoms of amaurosis fugax
Transient painless visual loss
“like a curtain coming down”
Lasts for 5 minutes then full recovery
Are there any findings on fundoscopy for amaurosis fugax
Usually no abnormal signs
management of GCA with visual impairment
IV methylprednisolone
Same day ophthalmology review
What does Virchow’s triad describe
the 3 factors that contribute to the development of venous thrombosis
What are the 3 factors in Virchow’s triad
Endothelial damage
Abnormal blood flow
Hypercoagulable state
Examples of conditions that can cause endothelial damage
Diabetes
Trauma / surgery
Atherosclerosiss
Examples of conditions that can cause hyper coagulable state
Malignancy
Pregnancy
Sepsis
IBD
Examples of conditions that can cause abnormal blood flow
Immobility
Afib
Left ventricular dysfunction
Obesity
Pregnancy
What is central retinal vein occlusion
Formation of thrombus in central retinal vein blocking drainage of blood from the retina
Risk factors of retinal vein occlusion
Increasing age
Hypertension
CVD
Diabetes
Glaucoma
What happens if venous drainage is blocked by thrombus
Blood pools in the retina
Leakage of fluid and blood -> macular oedema and retinal haemorrhages
Damage to tissue in the retina
Neovascularisation
Symptoms of retinal vein occlusion
Sudden painless loss of vision
Branch retinal vein occlusion may result in visual loss in the affected area only
Unilateral
What are the findings on fundoscopy for retinal vein occlusion
Macular oedema
Dilated tortuous veins
Blot haemorrhages, severe retinal haemorrhages
Widespread hyperaemia (widespread redness due to pooling of blood)
Management of retinal vein occlusion
Managed conservatively
IV Anti VEGF for macular oedema
Laser photocoagulation for retinal neovascularization
What is vitreous haemorrhage
Bleeding into the vitreous cavity
Where is the vitreous cavity
posterior chamber
What are the causes of vitreous haemorrhage
Proliferative diabetic retinopathy
Trauma
Retinal vein occlusion
Retinal tear
Symptoms of vitreous haemorrhage
If mild - floaters
If severe - acute painless visual loss or haze
Clinical signs of vitreous haemorrhage
Loss of red reflex
Haemorrhage on fundoscopy
Investigations for vitreous haemorrhage
fundoscopy
Ultrasound B scan of the eye
Fluorescein angiography
orbital CT
Management of vitreous haemorrhage
Treat underlying cause - e.g. laser photocoagulation / anti-VEGF / optimise blood glucose control
What is the muscle that control superior eyelid movement
levator palpebrae superioris
What are the muscles that control ocularmovement
Superior rectus
Inferior rectus
Medial rectus
Lateral rectus
Inferior oblique
Superior oblique
Describe the structure of levator palpebrae superioris
A small portion of LPS contains smooth muscle called superior tarsal muscle
Describe the innervation of levator palpebrae superioris
LPS - Oculomotor nerve CN III
Superior tarsal muscle (smooth muscle) - sympathetic nervous system
Describe the attachment of levator palpebrae superioris
Origin: from the lesser wing of sphenoid bone, right above optic foramen
Attachment: superior tarsal plate
Describe the action of levator palpebrae superioris
Elevate the upper eyelid
Where is the common origin of the 4 recti muscles
All originate from the common tendinous ring
What is the common tendinous ring
Ring of fibrous tissue surrounding the optic canal
Describe how do the rects muscles attach to the eye
Straight attachment to the eye = direct path from origin to attachment
Do the oblique muscles originate from common tendinous ring
No
Describe how do the oblique muscles attach to the eye
Angular attachment to the posterior surface of sclera
Describe the innervation of the recti muscles
All oculomotor CN III EXCEPT lateral rectus - abducens nerve CN VI
Describe the innervation of the oblique muscles
Superior oblique - trochlear nerve CN IV
Inferior oblique - oculomotor nerve CN III
Function of superior rectus muscle
Elevate when in abduction
Function of inferior rectus muscle
Depress when in abduction
Function of medial rectus
Adduct the eyeball
Function of lateral rectus
Abduct the eyeball
What is special about the attachment of superior oblique muscle
It originates from the sphenoid bone then passes through a trochlea so it attaches to the posterior sclera in an angular way
Superior oblique muscle is posterior to
Superior rectus
Inferior oblique muscle is posterior to
Lateral rectus
Function of superior oblique muscle
Depress when in adduction
Function of inferior oblique muscle
Elevate when in adduction
Causes of CN III palsy
Aneurysm
Uncal herniation through tentorium
Diabetes
Cavernous sinus thrombosis
Vasculitis
What is uncal herniation through tentorium
A type of brain herniation caused by increase in intracranial pressure
What causes uncal herniation through tentorium
Expanding mass lesions within the skull
Haemorrhage in brain
= increase intracranial pressure causing herniation
Most common cause of third nerve palsy
Aneurysm
Where is the aneurysm causing CN III palsy usually located at
Posterior communicating artery
Presentation of third nerve palsy CN III
Down and out eye
Ptosis
Pupils may be dilated
What causes the down and out eye in third nerve palsy
Due to unopposed superior oblique and lateral rectus muscles
- superior oblique function - depress when eye is adducted
- lateral rectus function - abduct the eye
What causes ptosis in third nerve palsy
Because levator palpaebrae superioris is innervated by CN III = cannot elevate eyelid
What causes a painful CN III palsy
Aneurysm
Causes of trochlear nerve palsy
Congenital
Blunt head trauma
Tumour
Microvascular
most common cause of trochlear nerve palsy CN IV in children
Congenital - present at birth
Most common cause of trochlear nerve palsy CN IV in adults
Trauma
Presentation of trochlear nerve palsy CN IV
Vertical diplopia when looking inferiorly - due to limitation of depression in adduction, the affected eye on adduction will be elevated
Contralateral Head tilt
Chin-down head posture
Why do patients with fourth nerve palsy CN IV present with variable head positioning
To compensate for the vertical diplopia
When is vertical diplopia usually noticed in patients with fourth nerve palsy
When reading a book / going downstairs
Cause of sixth nerve palsy (abducens nerve)
Raised intracranial pressure
Tumour
Congenital
Microvascular
Most common cause of sixth nerve palsy
Raised intracranial pressure
Symptoms of sixth nerve palsy
horizontal diplopia worse when attempt to look to the affected side
Esotropia - when the eye turns inwards due to unopposed adduction
What is internuclear ophthalmoplegia
Injury/dysfunction in the medial longitudinal fasciculus causing horizontal disconjugate eye movement
What is the medial longitudinal fascicules
Tract which acts as the central connection for CN III, CN IV and CN VI
Causes of internuclear ophthalmoplegia
Multiple sclerosis
Stroke
How does multiple sclerosis cause internuclear ophthalmoplegia
Multiple sclerosis causes demyelination of the medial longitudinal fasciculus
Presentation of internuclear ophthalmoplegia
Impairment of adduction
Horizontal nystagmus of the abducting eye on the CONTRALATERAL side
Describe the transmission of special sensory information from the retina to the lateral geniculate nucleus
- Axons of the retinal ganglion receive impulses from the photoreceptors of the eyes
- The axons then join together to form optic nerve
- Optic nerve enters the cranial cavity via optic canal
- Optic nerves from each eye unite to form optic chasm
- Fibres from the nasal (medial) half of each retina cross over each other
- Fibres from the temporal (lateral) half do not cross over - The nerves then enter a optic tract and each optic tract travels to Lateral geniculate nucleus
- Synapses at the lateral geniculate nucleus
Describe the transmission of special sensory information from the lateral geniculate nucleus to the visual cortex of occipital lobe
- Synapse at lateral geniculate nucleus -> optic radiations
- The radiations loop through parietal / temporal lobe
- The radiations that travel through the parietal lobe corresponds to the upper half of the retina hence lower visual field
- The radiations that travel through the temporal lobe corresponds to the lower half of the retina hence upper visual field
- the optic radiations terminate in the visual cortex which is at the occipital lobe, forming a final image
Where is the visual cortex located at
Occipital lobe
Describe the visual fields and each part of the eye responsible for it
The temporal part of left eye -> right visual field
The nasal part of left eye -> left visual field
The temporal part of right eye -> left visual field
The nasal part of right eye -> right visual field
Where is the defect at that causes total unilateral visual loss in one eye
Optic nerves of the affected eye before crossing over optic chasm
Causes of unilateral visual loss
Ischaemic optic neuropathy
Optic neuritis
What is optic neuritis
Inflammation of the optic nerve
What causes optic neuritis
Multiple sclerosis
Diabetes
Syphilis
Symptoms of optic neuritis
Progressive unilateral vision loss
Pain behind eye
Pain worse on eye movement
Poor discrimination of colours
Central scotoma - black/blurry/blind spot in the middle of one’s vision
Management of optic neuritis
High dose steroids- IV methylprednisolone
What drug is not indicated in optic neuritis. Why
Oral prednisolone. Due to increased risk of recurrent optic neuritis
Where is the defect at that causes bitemporal hemianopia
Optic chiasm
how does lesion at optic chiasm cause bitemporal hemianopia
Bitemporal hemianopia = loss of vision at outer half of each eye
The lesion affects the crossover at optic chiasm and the cross over is by the nasal half of optic fibres from each side
The nasal half of optic fibres of left eye is for left visual field and for the right eye it is for the right visual field which are both outer half of each eye
Causes of bitemporal hemianopia (optic chiasm defects)
Pituitary tumour - prolactinoma / acromegaly
Craniopharyngioma
Meningioma
What is homonymous hemianopia
Field defect in the same halves of both eyes i.e. right homonymous hemianopia = visual loss of right visual field of each eye
Where is the defect at that causes homonymous hemianopia
At the optic tract (after optic. chiasm before lateral geniculate nucleus)
if right homonymous hemianopia - lesion is at the left optic tract
What is superior homonymous quadrantanopia
Field defect in the superior field of both eyes for the same side
Where is the defect at that causes superior homonymous quadrantanopia
Optic radiation in temporal lobe on the contralateral side - i.e. if visual loss at superior left quadrant - the lesion is on the right
Causes of homonymous quadrantanopia/hemoanopia
Tumours
Demyelination
Vascular
Most common cause of homonymous hemianopenia with macular sparing
Occlusive cerebrovascular disease
Where is the defect at that causes homonymous hemianopenia with macular sparing
Occipital cortex
What is the main blood supply to optic nerve head
posterior ciliary arteries
What is ischaemic optic neuropathy
Occlusion of the posterior ciliary arteries causing infarction of optic nerve head
What is the most common cause of arteritic anterior ischaemic optic neuropathy
Giant cell arteritis GCA
Symptoms of arteritis anterior ischaemic optic neuropathy
Sudden, painless visual loss
If caused by GCA:
- headache
- scalp tenderness
- enlarged temporal arteries
Fundoscope findings for ischaemic optic neuropathy
Pale, swollen disc
Pale disc may suggest chronic atrophy of the disc
Larger Optic nerve cupping may be seen
What does optic nerve cupping mean
When the normal optic nerve cup increases in size due to loss of optic nerve fibres
Commonly caused by glaucoma but may also be seen in severe ischaemic optic neuropathy
Management of arteritic ischaemic optic neuropathy
IV methylprednisolone
What are the causes of non-arteritic anterior ischaemic optic neuropathy
Diabetes
Age
High cholesterol
Hypertension
What is papilloedema
Swelling of the optic disc due to increased intracranial pressure
How does increase in intracranial pressure cause papilloedema
Because the optic nerve sheath is continuous with the subarachnoid space
What factors contribute to the ICP
Brain
Blood
CSF
These need to remain constant because the skull is rigid and cannot expand
Causes of papilloedema
Lesions
Malignant hypertension
Idiopathic intracranial hypertension
Inadequate absorption of CSF / overproduction of CSF / obstruction to CSF circulation
Hydrocephalus (build up of CSF)
Idiopathic intracranial hypertension is a common cause of
Bilateral disc swelling in young females
If there is a lesion in the skull, does it cause an increase in intracranial pressure initially
When a mass expands, compensatory mechanisms will initially maintain a normal intracranial pressure
But eventually small increases in volume will produce larger and larger increases in intracranial pressure
-> compromise blood flow -> brain ischaemia and swelling -> brain herniation
Symptoms of papilloedema
Headache
Enlarged blind spot
Blurring of vision
What are the findings on fundoscope for papilloedema
Venous engorgement
Loss of venous pulsation
Blurring of optic disc margin
Complications of papilloedema
Chronic can cause optic atrophy
