Loss of vision Flashcards
what do you have to check in the history if someone presents with loss of vision?
s it unilateral or bilateral
was it sudden onset or gradual
what type of vision loss- blurred, distorted, black
any associated symptoms i.e. pain, redness, discharge
how would you examine a patient who presented with visual loss?
visual acuite - snellen chart fundal examination - ophthalmoscope, slit lamp or volk lens ancillary tests; - amsler chart - colour vision - visual field assessment - flouresciene angiography - optic coherence tomography
what is the most common cause of colour vision loss?
damage to the optic nerve
if there is swelling in the optic disc what does this indicate?
pappiloedema
what is the most common cause of loss of visual field?
glaucoma
what are the main causes of sudden loss of vision?
central retinal artery occlusion
central retinal vein occlusion
anterior ischemic optic neuropathy - arteritic (giant cell arteritis) or non arteritic
in assessing a patient with sudden loss of vision, how would you know if it was due to central retinal artery occlusion?
when shining a light in the ‘bad eye’ the pupil won’t constrict
but if you shine a light in the ‘good’ eye then the bad eye will constrict
what treatment is given for central retinal artery occlusion?
intravitreal Vegf
also identify and treat risk factors i.e. BP, statin, blood thinner, aspirin etc.
how does central retinal vein occlusion occur?
hypertension causing thickening of the artery which then compresses the nearby vein
inflammation within the wall of the vein = periphlebitis
hyper viscosity syndrome
how does intravitreal VegF work?
blocks activity of vascular endothelial growth factor
therefore it will stop the production/leaking of oedema and blood from blood vessels
how does occlusion of the central retinal artery cause visual loss?
these blood vessels are very leaky so blood and fluid seeps out resulting in haemorrhages throughout the retina
this damages the architecture of the retina affecting vision
what arteries are involved in anterior ischaemic optic neuropathy?
short posterior ciliary arteries
what is the pathophysiology of giant cell arteritis?
inflammation of the short posterior ciliary arteries which thickens the wall of the vessels
this causes obstruction of the lumen
= blockage = infarction of optic nerve
what are the symptoms of giant cell arteritis?
loss of vision headaches loss of appetite scalp tenderness pain on chewing
what are the signs of giant cell arteritis?
tenderness of superficial temporal arteries (they are also involved in the same inflammatory process)
pale swollen optic nerve
raised ESR & CRP
