5: Visual loss and blindness Flashcards
What is the major artery supplying the eye?
Which artery in the neck does it stem from?
Ophthalmic artery
Internal carotid artery
What are the important branches of the ophthalmic artery which you should know?
Central retinal artery (inner 2/3rds of retina)
Posterior ciliary arteries (optic nerve head)
Which structure supplies the other 1/3rd of the retina?
Choroid
What vascular problems cause sudden visual loss?
Occlusion
Haemorrhage
Which artery supplies the inner 2/3rds of the retina?
Central retinal artery
What are the symptoms of central retinal artery occlusion?
Sudden profound vision loss
Which is painless
What reflex is disrupted in CRAO?
Pupillary light reflex
pupil doesn’t constrict in response to light - relative afferent pupil defect (go back and forth fast enough and the pupil will actually dilate in response to light)
because optic nerve is infarcted
What does the retina look like in a central retinal artery occlusion?
Pale
Cherry spot fovea
Arteries either absent or blocked
Central retinal artery occusion is a type of ___.
stroke
What causes central retinal artery occlusion?
Carotid artery disease
How are central retinal artery occlusions managed?
Ocular massage (attempt to convert to branch occlusion)
Manage risk factors
What is amaurosis fugax?
Transient central artery occlusion
What are the symptoms of amaurosis fugax?
Transient painless visual loss
lasting 5 mins with full recovery
How is amaurosis fugax treated?
Aspirin (anti-platelet)
Urgent referral to stroke clinic
What is Virchow’s triad?
Endothelial injury
Hypercoagulability
Stasis / turbulent blood flow
What are the symptoms of central retinal vein occlusion?
Sudden painless visual loss
CRVO is associated with a raised ___ pressure.
intraocular
What are the signs of CRVO on fundoscopy?
Haemorrhages - inc. cotton wool spots
Dilated torturous veins
Optic disc and macular swelling
What type of scan is used to pick up macular oedema?
OCT scan
How is CRVO treated?
Laser treatment
Anti-VEGF injections (VEGF released in response to ischaemia, encourages development of poorly structured blood vessels which haemorrhage)
Address risk factors
What processes drive
a) arterial
b) venous
occlusions of the eye?
a) Internal carotid disease
b) Venous stasis
Which arteries supply the optic nerve head?
Posterior ciliary arteries
What is occlusion of the posterior ciliary arteries also known as?
Ischaemic optic neuropathy
What tends to cause arterial ischaemic optic neuropathy?
Giant cell arteritis
What causes non-arteritic ischaemic optic neuropathy?
Atherosclerosis
What does the optic disc look like in ischaemic optic neuropathy?
Swollen
What is the main symptom of arteritic ischaemic optic neuropathy?
Sudden irreversible visual loss
Irreversible blindness is an end-stage symptom of giant cell arteritis. What are the other symptoms?
Headache
Jaw claudication
Scalp tenderness
Tender, enlarged temporal arteries
Transient arterial occlusions (amaurosis fugax)
Malaise
Raised inflammatory markers
How is giant cell arteritis treated to prevent immediate bilateral blindness?
High dose oral prednisolone
Where in the eye does bleeding tend to occur?
Vitreous cavity
What is a bleed into the vitreous cavity called?
Vitreous haemorrhage
What are the symptoms of vitreous haemorrhage?
Loss of vision
Floaters
What are signs of vitreous haemorrhage on fundoscopy?
Loss of red reflex
Clear haemorrhage
How is vitreous haemorrhage managed?
Management of underlying disease
Vitrectomy
What are the symptoms of retinal detachment?
GRADUAL painless loss of vision
Flashes
Floaters
What is the commonest cause of blindness in elderly people?
Age-related macular degeneration (ARMD)
What are the two types of ARMD?
Wet (sudden)
Dry (gradual)
What causes wet ARMD?
New blood vessels grow in choroid, causing fluid bulge and scarring
What are the symptoms of wet ARMD?
Rapid CENTRAL vision loss
Metamorphopsia - visual distortion
How is wet ARMD treated?
Anti-VEGF injections
What is the jist of glaucoma?
Damage to optic nerve
What are two different types of glaucoma?
Open-angle
Closed-angle
Where does aqueous fluid drain?
Canal of Schlemm (trabecular meshwork) at iridocorneal angle
What causes closed-angle glaucoma?
Blockage of trabecular network by bulging iris causes increased IOP
What are the symptoms of closed angle glaucoma?
Painful, red eye
Sudden peripheral visual loss
Headache, nausea, vomiting
How is closed angle glaucoma treated?
Lower IOP with drops - carbonic anhydrase, beta blockers etc.
Laser iridotomy - trabeculectomy???
What are some causes of gradual visual loss?
Cataracts
Dry ARMD
Refractive error
Glaucoma
Diabetic retinopathy
What are cataracts?
Cloudiness of the lens
Which drugs can induce cataracts?
Steroids
When would cataracts be managed?
How?
If symptomatic
Surgical lens implant
Dry ARMD causes (sudden / gradual) visual loss.
gradual visual loss
ARMD causes (central / peripheral) vision loss.
central vision loss
What causes dry ARMD?
Build-up of DRUSEN - waste products below retina
Causes retina to tent away from choroid and become atrophic
How is dry ARMD treated?
Supportively - magnifiers, care etc.
What is refractive error?
Eye cannot clearly focus an image
What is myopia?
Which type of lens is used to treat it?
Short-sightedness
Light focused TOO EARLY, BEFORE RETINA
Treated using concave lens (diverges light)
What is hypermetropia?
Which type of lens is used to treat it?
Long-sightedness
Light focused too LATE
Treated using convex lenses
What is astigmatism?
Irregular CORNEAL curvature
What is presbyopia?
Loss of accommodation reflex with aging
What type of glaucoma causes gradual visual loss or is asymptomatic?
Open-angle glaucoma
What are the signs of open-angle glaucoma?
Cupped disc
Visual field defects
but patient may be asymptomatic
What is the cup:disc ratio like in glaucoma?
Too big
Where does visual loss occur first in glaucoma?
Peripheral first
Do patients with glaucoma have tunnel vision?
No - they fill in the rest of the image (incorrectly)
How is open-angle glaucoma treated?
Drops to lower BP
Laser treatment
Surgery
