Visual loss Flashcards
What is a cataract?
a progressive clouding of the lens which impairs function
What can cause cataracts?
age congenital trauma metabolic eg. diabetes steroids intrauterine infection eg rubella
What is the most common type of cataract?
nuclear sclerotic
How can cataracts be managed?
surgically with phacoemulsification and artificial intra-ocular lens implantation
What is the commonest cause of blindness in the West in those over 65?
Age related macular degeneration (ARMD)
What part of the visual field is affected by macular degeneration?
central vision
What is dry ARMD?
wear and tear of the retinal pigment epithelium causing slow, progressive visual loss
What characterises dry ARMD?
drusen
RPE hypo/hyperpigmentation
What is wet ARMD?
dry + neovascular changes
- eye tries to repair damage but the new vessels are leaky and bleeding causing sudden devastating decrease in central visual acuity
What can predict wet ARMD before a devastating bleed?
metamorphsia (distortion of straight lines to wavy)
How can wet ARMD be treated?
anti-vegf
Give causes of gradual visual loss
cataracts
dry ARMD
chronic open angle glaucoma
diabetic retinopathy
Give causes of sudden painless loss of vision
central retinal artery occlusion (CRAO)
central retinal vein occlusion (CRVO) or branch retinal vein occlusion
anterior ischaemic optic neuropathy (AION)
retinal detachment
Give causes of sudden painful loss of vision
acute closed angle glaucoma
optic neuritis
giant cell arteritis
How does CRAO present?
sudden profound visual loss + RAPD
What does CRAO look like on exam?
pale swollen retina with a cherry red spot at the macula
What can cause CRAO?
giant cell arteritis
embolic
carotid artery disease
How is CRAO managed?
treat within 12-24hrs by dislodging blockage
- massage
- paper bag breathing
- IV acetazolamide
- anterior chamber paracentesis
How can paper bag breathing manage CRAO?
inc PaCO2 causes vasodilation
How does CRVO present?
mod-severe visual loss +/- RAPD
How does CRVO appear on exam?
flame haemorrhages
tortuous vessels
swollen disc
cotton wool spots
What do cotton wool spots indicate in CRVO?
ischaemia
How is CRVO managed?
if not ischaemic observe 3 monthly
if neovascularisation observe monthly
if ischaemic –> argon laser
What is anterior ischaemic optic neuropathy (AION)?
disrupted blood supply to the anterior optic nerve