Visual Loss and Blindness Flashcards
name 7 causes of sudden visual loss
vascular vitreous haemorrhage retinal detachment age related macular degeneration (wet type) closed angle glaucoma optic neuritis stroke
what is the main blood supply to the eye?
branches of the ophthalmic
- posterior ciliary arteries (either side of central retinal artery)
- central retinal artery (in the middle)
occlusion of what can cause sudden visual loss?
retinal circulation (retinal artery/vein) optic nerve circulation
haemorrhage from where can cause sudden visual loss?
abnormal blood vessels
normal blood vessels
what does the central retinal artery supply?
2/3rds of retina
symptoms and signs of occlusion of retinal circulation (central retinal artery)
sudden vision loss painless RAPD pale, oedematous retina (as vessels occluded so not red) thread like retinal vessels
why is the macula normal in central retinal artery occlusion?
no ganglion cells in macula
name 2 causes of central retinal artery occlusion (CRAO)?
carotid artery disease
emboli from the heart (unusual)
name 2 further variants of CRAO
branch retinal artery occlusion (less severe as only a branch, problems in bottom half of vision)
amaurosis fugax
what are the features of amaurosis fugax?
transient, painless visual loss
“like a curtain coming down”
lasts 5 mins with full recovery
usually nothing abnormal on examination
management of amaurosis fugax?
urgent referral to stroke clinic
virchows triad?
hypercoagulable blood (e.g cancer) turbulent blood flow (e.g hypertension) endothelial damage (e.g diabetes)
signs and symptoms of central retinal vein occlusion?
sudden visual loss (severity dependent on level of ischaemia)
retinal haemorrhages
dilated, tortuous veins
disc swelling and macular swelling
can have cotton wool spots (markers of ischaemia)
can have fluid build up around macula (oedema)
artery vs vein occlusion (colour)?
artery = pale vein = dark
what vessels supply the optic nerve?
posterior ciliary arteries
what is ischaemic optic neuropathy?
occlusion of optic nerve head circulation
posterior ciliary arteries become occluded, resulting in infarction of the optic nerve head
name a cause of ischaemic optic neuropathy and how this occurs?
giant cell arteritis
medium to large sized arteries inflamed (via multinucleate giant cells) > lumen of artery becomes occluded (posterior cilliary arteries) due to gross thickening of artery wall > visual loss from ischaemia of optic nerve head
symptoms and signs of ischaemic optic neuropathy?
sudden severe visual loss
irreversible blindness
swollen optic nerve
6 symptoms of giant cell arteritis?
headache (usually temporal) jaw claudication scalp tenderness tender/enlarged scalp arteries amaurosis fugax malaise
where does haemorrhage often occur into and what is this known as?
into vitreous cavity
known as vitreous haemorrhage
how can haemorrhages occur in the eye?
bleeding occurs from abnormal vessels (e.g retinal ischaemia in diabetes or retinal vein occlusion causes abnormal, fragile new blood vessels to form
bleeding can occur from normal vessels (e.g vessel bridging a retinal tear)
name 5 signs and symptoms of vitreous haemorrhage
loss of vision floaters loss of red reflex may see haemorrhage on fundoscopy find a cause
4 signs and symptoms of retinal detachment?
painless loss of vision
sudden onset of flashes/floaters (mechanical separation of sensory retina from retinal pigment epithelium)
may have RAPD
may see tear on ophthalmoscopy
what can cause a retinal detachment?
tear in retina
vitreous humour can pull on the retina causing a tear
vitreous humor (which is more liquid in older people) can go through the hole and get behind the sensory retina and separate it from the retinal pigment epithalium
what is the most common cause of blindness in the west?
age related macular degeneration (ARMD)
what are the 2 types of ARMD?
wet (sudden visual loss)
dry (gradual visual loss)
risk factors for ARMD?
increasing age
smoking
family history
poor nutrition
what happens in wet ARMD?
new vessels start to grow from the choroid up into the retina
leakage causes build up of fluid/blood and eventually scarring
5 signs and symptoms of wet ARMD?
rapid central visual loss
distortion (metamorphosia) = straight lines look wiggly
haemorrhage/exudate
swelling/raised up area on imaging (fluid build up)
pale area on retina (oedema from fluid)
what is glaucoma?
progressive optic neuropathy
ultimately results in optic nerve damage and therefore visual loss
what are the 2 types of glaucoma?
open angle (angle between iris and cornea) closed angle
what happens in closed angle glaucoma?
aqueous humour encounters increased resistance through iris/lens channel
increased pressure gradient causes peripheral iris to bow forward, obstructing trabecular meshwork - pressure increases
features of closed angle glaucoma?
acute (ophthalmic emergency) painful, red eye sudden visual loss headache nausea and vomiting cloudy cornea dilated pupil
immediate management of closed angle glaucoma?
need to lower IOP with drops/oral medication to prevent blindness
general presentation of gradual visual loss?
usually bilateral
often asymmetrical
may present early with reduced VA
may present late with decreased field
name 5 causes of gradual visual loss
cataract age related macular degeneration (dry) refractive error glaucoma diabetic retinopathy
what is cataract?
cloudiness of the lens
abnormal changes in lens protein (crystallina) result in their chemical and structural alteration, leading to loss of transparency
causes of cataract?
age related congenital (intrauterine infection) traumatic metabolic (diabetes - sorbitol accumulation) drug indiced (steroids)
what does a nuclear cataract looks like?
when beam of light is shone on cornea, shows as greenish/brown colour on lens
what does a posterior subcapsular cataract look like?
separate distinct beam of light in lens??
Christmas tree cataract?
crystals in the lens are visible
look like Christmas tree lights
name 2 symptoms of cataracts
gradual decline in vision (hazy/blurred) that cannot be corrected by glasses
may get glare
management of cataract?
surgical removal with intra-ocular lens implant if patient is symptomatic
what happens in dry ARMD?
accumulation of drusen (metabolic by products of pigment epithelium)
drusen builds up and separates the retina from the vascular supply in the choroid, which can lead to ischaemia etc?
4 signs and symptoms of dry ARMD?
gradual decline in vision
central vision missing (scotoma)
drusen build up below retinal pigment epithelium
atrophic patches on retina
how is dry ARMD managed?
no cure
supportive treatment
what happens in refractive error?
eye cannot clearly focus image
name 4 types of refractive error
myopia (short sighted)
hypermetropia (long sighted)
astigmatism (usually irregular corneal curvature)
presbyopia (loss of accommodation with ageing)
management of refractive error?
glasses
5 symptoms and signs of open angle glaucoma?
often none optician may discover it cupped disc visual field defect may/may not have high Intra-ocular pressure
