Visual loss and blindness Flashcards
what can cause sudden visual loss
vascular aetiology (retinal artery/ vein occlusion), vitreous haemorrhage, retinal detachment, ARMD wet type, closed angle glaucoma, optic neuritis, stroke
what is the main blood supply to the eye
branches of the ophthalmic
what supplies the optic nerve head
posterior cilliary artery
what vessel supplies the retina
central retinal artery
occlusion of what vasculature can cause sudden visual loss
retinal circulation (retinal artery and vein) optic nerve circulation
what haemorrhage can cause sudden visual loss
abnormal vessels (DM, wet ARMD) normal vessels (bridging a retinal tear)
what are the signs and symptoms of central retinal artery occlusion
sudden visual loss
painless
RAPD
pale oedematous retina, thread like retinal
why do oedematous retinal ganglions make the eye appear pale
as choroid blood vessels underneath that make the eye appear red are no longer visible
why doesnt the macula get paler when ganglion cells become odematous (in central retinal artery occlusion)
as macula doesnt have ganglion cells over it
what can cause central retinal artery occlusion
carotid artery disease
emboli from the heart (vegetations/ thrombus on heart valve)
what is branch retinal artery occlusion
only one branch affected so partial vision loss
how do you tell the vessels apart in a fundoscopy
lighter one is the artery
darker one is the vein
what is amaurosis fugaxyout
transient central retinal artery occlusion
what are the symptoms of amaurosis fugaxyout
transient painless visual loss
‘like a curtain coming down’
last about 5 mins with full recovery
nothing abnormal on examination
what should you do in amaurosis fugaxyout
urgent referral to stroke clinic
what is central retinal vein occlusion associated with
endothelial change (diabetes) abnormal blood flow (hypertension) hypercoaguable state (cancer)
(neighbouring artery may stiffen and occlude vein)
what are the symptoms of central retinal vein occlusion
sudden visual loss
what are the signs of central vein occlusion
retinal haemorrhages, dilates tortous veins, disc swelling and macular swelling, cotton wools spots
what are cotton wool spots
ischaemia- small infarcts of the nerve fibres
what are the differences in artery and vein occlusion
artery will cause oedema
vein will cause haemorrhages
what is ischaemic optic neuropathy
occlusion of optic nerve head circulation (posterior ciliary arteries)
what inflammatory condition can cause ischaemic optic neuropathy
giant cell arteritis - lumen of artery becomes occluded due to gross thickening of artery wall
what cells id GCA
multinucleated giant cells
what are the visual symptoms and signs of ischaemic optic neuropathy
sudden severe visual loss
irreversible blindness
swollen optic disc, pale
what can immediate treamtment of ischaemic optic neuropathy prevent
bilateral visual loss
what are the symptoms of GCA
headache (temporal) jaw claudication scalp tenderness (painful to comb hair) tender/enlarged scalp arteries amaurosis fugax (transient darkness) malaise
what is a vitreous haemorrhage
a haemorrhage that occurs in the vitreous cavity of the eye
what can cause an abnormal vessel haemorrhage
e.g. in retinal ischaemia in diabetes/ retinal vein occlusion new fragile (curly) blood vessels form which bleed easily
what are the signs and symptoms of vitreous haemorrhage
loss of vision
floaters
loss of red reflex
may see haemorrhage on fundoscopy
what does the red reflex tell you
that the media is clear
what are the 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 causes ARMD
multifactoral- age, smoking, family history, poor nutrition
what are the types of ARMD
wet- sudden visual loss
dry- gradual
describe wet ARMD
new blood vessels grow under retina from pigment epithelium up through the choroid
leakage causes build up of fluid/ blood and eventually scarring
what are the signs and symptoms of wet ARMD
rapid central visual loss
distortion (metamorphosia)
haemorrhage/ exudate
eye pale due to oedema
flecks in eye exudates from vessels
what is glaucoma
progressive optic neuropathy leads to optic nerve damage
what is the angle in glaucoma
angle between the iris and the cornea
what is the path of aqueous fluid
produced by the ciliary body, travels between the iris and lens into the trabecular meshwork
what causes closed angle glaucoma
aqueous humour encounters increased resistance through the iris/lens channel
increased pressure gradient causes peripheral iris to bow forward, obstructing trabecular meshwork- increasing pressure
what are the signs and symptoms of closed angle glaucoma
acute (ophthalmic emergency)
painful, red eye, sudden visual loss, headache, N&V
red eye, cloudy cornea, dilated pupil
what is the treatment for closed angle glaucoma
lower IOP with drops/ oral medication to prevent blindness
what are the causes of gradual visual loss
cataract, ARMD (dry type), refractive error, glaucoma, diabetic retinopathy
what is cataracts
cloudiness of the lens- abnormal changes in lens proteins (crystallins) causes changes in their chemical and structural nature causing them to loose their transparency
what causes cataracts
age, congenital (intrauterine infection), traumatic, metabolic (diabetes- reductase glucose to sorbitol), drugs (steroids)
what are the different types of cataracts
nuclear
posterior (subcapuslar)
christmas tree (polychromatic)
congenital
what are the symptoms of cataracts
gradual decline in vision (hazy/blurred)
glare
when is surgery done for cataracts
is patient is symptomatic
what is the commonest cause of blindness in western world in patients over 65
ARMD
what type of of ARMD do you get drusens in
what are they?
dry type- they are bi products of pigment cells which build up and stop nutirents diffusing through the choroid- retina becomes atrophic
what are the signs and symptoms of dry type ARMD
gradual decline in vision
central vision missing (scrotoma)
drusen (yellow flakes)
atrophic patches of retina
what is the treatment for dry type ARMD
none- vision aids
what is myopia
short sighted- image focused infront of the retina of the retina
what is hypermetropia
long sighted- image focused behind the retina
what is astigmatism
usually irregular corneal curvature
what is presbyopia
loss of accommodation with age
what is the treatment for refractive error
glasses
describe open angle glaucoma
Trabecular meshwork gets clogged up and doesn’t allow the fluid draining from the eye
Pressure increases gradually
what are the signs and symptoms of open angle glaucoma
often none
cupped disc
visual field defect
may/ not have raised IOP
