Visual Loss Flashcards
What are the causes of sudden visual loss?
Wet age-related macular degeneration (ARMD) Central retinal artery/vein occlusion Virtual haemorrhage Closed angle glaucoma Retinal detachment
What artery is the main blood supply to the eye?
Ophthalmic artery
What are the main branches of the ophthalmic artery?
Central retinal artery
Posterior ciliary arteries
What are the vascular causes of sudden visual loss?
Occlusion of retinal circulation or optic nerve circulation
Haemorrhage form normal (bridging a retinal tear) or abnormal (DM, wet AMD) blood vessels
What are the causes of central retinal artery occlusion (CRAO)?
Carotid artery disease
Emboli from atheroma
Emboli from diseased heart valves
Giant cell arteritis
What part of the retina does the central retinal artery supply?
Inner 2/3rds
outer 1/3rd supplied by choroid
What are the symptoms of CRAO?
Sudden, usually painless, visual loss
What are the clinical signs of CRAO?
Relative afferent papillary defect (RAPD)
What signs of CRAO are seen on ophthalmoscopy?
Pale, oedematous retina
Cerry red spot at fovea
Narrow, thread-like vessels
Why is there a pale retina but cherry red spot in CRAO?
Oedema within the retina occurs which obscures the choroid (which usually gives the red colour) but the retina is very thin at the fovea so vasculature shows through
What are two other types of retinal artery occlusion other than CRAO?
Branch retinal artery occlusion Amaurosis fugax (transient CRAO lastin 5 mins or so_)
What factors is central retinal vein occlusion (CRVO) associated with?
Endothelial damage
Hypercoagulable state
Abnormal blood flow
What is the pathogenesis of CRVO?
Often the retinal artery crosses over the vein
If the artery becomes atherosclerotic it becomes a rigid structure, which can limping upon the vein
This can lead to haemodynamic disturbance, endothelial damage and thrombus formation
What are the risk factors for CRVO?
Increasing age Hypertension and CVD Diabetes Glaucoma Blood dycrasias and vasculitis
What are the symptoms of CRVO?
Sudden, usually painless, visual loss
What signs of CRVO are seen on ophthalmoscopy?
Retinal haemorrhages
Dilated, tortuous veins
Disc swelling and macular swelling
Cotton wool spots
What is ischaemic optic neuropathy?
Occlusion of optic nerve head circulation (posterior ciliary arteries)
What are the symptoms of ischaemic optic neuropathy?
Sudden (or stuttering) visual loss
Typically the lower half of the visual field
Usually painless
What are the signs of ischameic optic neuropathy on ophthalmoscopy?
Swollen optic nerve
Later - optic atrophy
Bilateral later in 1/3rd of cases
What needs to be a consideration in ischaemic optic neuropathy?
Giant cell arteritis
What is giant cell arteritis?
An inflammatory condition where posterior ciliary arteries become inflamed and the lumen becomes occluded
This affects other arteries, including temporal arteries
What are the symptoms of giant cell arteritis?
Headache
Scalp tenderness
Enlarged temporal arteries
How can diabetes or retinal vein occlusion cause vitreous haemorrhage?
These cause retinal ischaemia which causes abnormal new vessels to form
These are very fragile and bleed easily
How can vitreous haemorrhage occur from normal vessels?
When a vessel bridges a retinal tear it can break and haemorrhage