week 2 visual loss and blindness Flashcards
what are the two types of visual loss?
sudden
gradual
causes of sudden visual loss
Vascular aetiology Vitreous haemorrhage Retinal detachment Age related macular degeneration (ARMD) -wet type Closed angle glaucoma optic neuritis stroke
what are the two branches of the ophthalmic artery we need to know?
PCA- posterior ciliary artery
CRA - central retina artery
what does the CRA supply?
inner 2/3rds of retina
the PCAs supply what?
optic nerve head
the choroid arteries supply what?
outer 1/3rd of retina
sudden loss of vision occurs why?
occlusion =
- retinal circulation
- optic nerve head circulation
haemorrhage=
- abnormal blood vessels (eg diabetes, wet ARMD)
- retinal tear
symptoms of CRAO
- Sudden visual loss
- Profound (Count Fingers or less- remember CRA is ‘end artery’)
- Painless (unless GCA)
signs of CRAO
- RAPD (relative afferent pupil defect)
- Pale oedematous retina, thread-like retinal vessels
causes of CRAO
Carotid artery disease (type of stroke)
Emboli from the heart (unusual)
management of CRAO
If presents within 24 hours: = Ocular massage (try to convert CRAO to BRAO)
Vascular management:
=Establish source of embolus – carotid doppler
=Assess and manage risk factors
what is BRAO/BRVO
branch retinal artery occlusion - less visual loss
branch retinal vein occlusio
what is amaurosis fugax
transient CRAO
symptoms of amaurosis fugax
transient painless visual loss
‘like a curtain coming down’
lasts~5mins with full recovery
amaurosis fugax: signs
Usually nothing abnormal to see on examination
amaurosis fugax treatment
Urgent referral Stroke clinic
Aspirin (unless contraindicated)
what potential other cases of amaurosis fugax/transcient vision loss other than occlusion and then unblocking?
Migraine – visual loss usually followed by headache
what is the pathogenesis being CRVO?
SYSTEMIC:virchow’s triad = stasis, hyper coagulability, endothelial damage
OCULAR: raised IOP (venous stasis)
symptoms of CRVO
Sudden visual loss
Moderate to severe visual loss (6/9 – Percepion of Light)
CRVO; signs
Retinal haemorrhages
Dilated tortuous veins
Disc swelling and macular swelling
treating CRVO
Monitor: may develop complications due to development of new vessels (laser treatment may be required to avoid complications from these vessels eg vitreous haemorrhage)
More recently, anti- VEGFs used to stop new blood vessel growth(VEGF = vascular endothelial growth factor)
Address underlying risk factors eg hypertension, diabetes
what is the difference of fundoscopy of artery vs vein occlusion?
pale - artery occlusion
drak - vein occlusion
what is Ischaemic optic neuropathy?
ION
Occlusion of optic nerve head circulation
pathology of ION
Posterior ciliary arteries (PCA) become occluded, resulting in infarction of the optic nerve head
(PCA not end arteries)
what are the two types of ION?
Arteritic 50% - inflammation (GCA)
Non-arteritic 50% - atherosclerosis
PC of ION (both arthritic and non-arteritic)
sudden, profound visual loss with swollen disc
pathogens of arthritic ION
Giant cell arteritis (GCA)
Medium to large sized arteries inflamed (infiltrated by multinucleate giant cells)
Lumen of artery becomes occluded (posterior ciliary arteries)
Visual loss from ischaemia of optic nerve head
visual symptoms of arthritic ION
Sudden visual loss
Profound (CF – NPoL)
Irreversible blindness
(diagnose quick to stop bilateral loss)
systemic symptoms of arthritic ION
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
treatment of GCA
refer urgent, high dose steroids urgent - then biopsy
how can sudden visual loss occur from haemorrhage?
- abnormal blood vessels (eg diabetes, wet ARMD)
- retinal tear
symptoms of vitreous haemorrhage
Loss of vision
‘Floaters’
signs of vitreous haemorrhage
Loss of red reflex
May see haemorrhage on fundoscopy
management of vitreous haemorrhage
indentfy casue
Vitrectomy for non-resolving cases (lots of people need surgery)
symptoms of Retinal Detachment
Painless loss of vision
Sudden onset of flashes/floaters (mechanical separation of sensory retina from retinal pigment epithelium)
“curtain coming down”
Retinal Detachment
May have RAPD
May see tear on ophthalmoscopy
Retinal Detachment management
ususally surgical
what are the two types of age related macular degeneration (ARMD) + PC
dry (gradual visual loss)
wet (sudden)
what is the Commonest cause of blindness in Western World in patients over 65
ARMD
pathogenesis of wet ARMD
New blood vessels grow under retina – leakage causes build up of fluid/blood and eventually scarring
wet ARMD: symptoms
Rapid central visual loss
Distortion (metamorphopsia
wet ARMD: signs
haemorrhage/exudate
what is blind spot called?
scotoma
treatment of Wet ARMD
Previously:
Laser
Photodynamic therapy
Now:
Anti-VEGF treatment – injected into vitreous cavity. Stops new blood vessels growing by binding to VEGF (vascular endothelial growth factor)
what is Glaucoma
Progressive optic neuropathy, Ultimately result in optic nerve damage (and therefore, visual loss)
risk factor for glaucoma
high IOP
describe what close-angle glaucoma is?
Aqueous humour encounters increased resistance through iris/lens channel
Increased pressure gradient causes peripheral iris to bow forward, obstructing trabecular meshwork – pressure increases
(iris blocks drainage)
treating closed-angle glaucoma
Need to lower IOP with drops/oral medication to prevent patient going blind, then do laser iridotomy
(can be acutely painful/emergencyl)
PC of glaucoma closed angle
Patient presents with painful, red eye/visual loss/headache/nausea/vomiting
characteristics of gradual vision loss
Bilateral – usually
Often asymmetrical
May present early with reduced Visual acuity
May present late with decreased field
causes of gradual vision loss
Cataract
Age related macular degeneration (dry type)
Refractive error
Glaucoma
Diabetic retinopathy
what is cataract
Cloudiness of the lens
causes of cataract
Age related Congenital – intrauterine infection (importance of checking red reflex in neonates) Traumatic Metabolic – diabetes Drug-induced (steroids)
what is the number one cause of preventable blindness worldwide
cataract
symptoms of cataract
Gradual decline in vision (‘hazy’ / ‘blurred’) that cannot be corrected with glasses
May get glare (can be very disabling at night when driving)
management of cataract
surgical removal with intra-ocular lens implant if patient is symptomatic
symptoms of dry ARMD
Gradual decline in vision
Central vision ‘missing’ (scotoma)
signs of dry ARMD
Drusen – build up of waste
products below RPE
atrophic patches of retina
treatment for dry ARMD
no cure - treatment is supportive with low vision aids eg magnifiers
refractive error means what?
Eye cannot clearly focus image
treat by glasses
myopia
short sighted
hypermetropia
long sighted
astigmatism
usually irregular corneal curvature
presbyopia
loss of accommodation with aging
glaucoma open-angle pathogenesis
angle is ‘open’ but there is resistance to outflow of aqueous in trabecular meshwork
glaucoma open-angle symptoms
Often NONE
Optician may discover it
glaucoma open-angle signs
Cupped disc
Visual field defect
May/may not have high IOP
glaucoma open angle treatment
aim to preserve vision (by lowering IOP) with eye drops /laser/surgery
Patients need regular monitoring in eye clinic
