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
What are the symptoms of vitreous haemorrhage?
Sudden loss of vision
Floaters
What are the clinical features of vitreous haemorrhage?
Loss of red reflex
What signs of vitreous haemorrhage can be seen on ophthalmoscopy?
May see a haemorrhage
What are the symptoms of retinal detachment?
Painless loss of vision
Sudden onset of flashes/floaters
What causes flashes and floaters?
Mechanical separation of sensory retina from retinal pigment epithelium
What are the clinical signs of retinal detachment?
May have RAPD
What signs of retinal detachment can be seen on ophthalmoscopy?
May see a tear
What is rhegmatogenous retinal detachment?
Where a tear in the retina causes the rest of the retina to peel away from retinal pigment epithelium
What is the commonest cause of blindness in the UK?
Age related macular degeneration (ARMD)
What is the cause of ARMD?
Unknown
What are the risk factors for ARMD?
Increasing age
Smoking
Positive family history
Poor nutrition
What are the two types of ARMD, and what is the main difference?
Wet - sudden loss of vision
Dry - gradual loss of vision
What is the physiology of wet ARMD?
New abnormal blood vessels grow under the retina in the region of the macula
Leakage causes buildup of fluid/blood and eventually scarring
What are the symptoms of wet ARMD?
Rapid central visual loss
Distortion of vision (metamorphopsia)
What signs of wet ARMD can be seen on ophthalmoscopy?
Haemorrhage
Hard exudates
What is the treatment for wet ARMD?
Anti-VEGF
What is glaucoma?
Progressive optic neuropathy (probably) caused by increased intraocular pressure
What are the two types of glaucoma?
Open angle and closed angle
What is the pathogenesis of closed angle glaucoma?
Resistance to aqueous fluid passing out through the iris/lens channel causes fluid to build up, which starts to push the iris forward
This closes the angle between the iris and the cornea, blocking the drainage of fluid through trabecular meshwork - pressure increases further
What are the symptoms of closed angle glaucoma?
Very painful
Sudden visual loss
Headache
Nausea, vomiting
What are the clinical signs of closed angle glaucoma?
Red eye
Cloudy cornea
Mid-dilated pupil
What is the treatment for closed angle glaucoma?
Lower intraocular pressure with drops/oral medication to prevent the patient from going blind
Surgery can be done if medication not sufficient
What are the causes of gradual visual loss?
ARMD Refractive error Cataract Diabetes Open angle glaucoma
What are cataracts?
Abnormal changes in lens proteins that result in their chemical and structural alteration, leading to loss of transparency - clouding of the lens
What are the causes of cataracts?
Age-related
Congenital
Diabetes
Drug induced (oral steroids)
What are the different types of cataracts?
Nuclear cataract
Posterior sub-capsular cataract
Christmas tree cataract
Congenital cataract
What are the symptoms of cataracts?
Gradual visual loss (hazy/blurred)
What is the management for cataracts?
Surgical removal with intra-ocular lens implant if patient is symptomatic
What is dry ARMD?
Tiny build up of yellow-white lesions under the retina made of lipid and metabolic by-products from pigment epithelial cells
Deposits build up and stop diffusion of nutrients from the choroid
The retina overlying this area becomes thin and atopic and loses its function - visual loss
What are the symptoms of dry ARMD?
Gradual decline in vision
Central vision missing (scotoma)
What signs of dry ARMD can be seen on ophthalmoscopy?
Drusen - build up of waste products
Atrophic patches to the retina
What is the treatment for dry ARMD?
No cure
Low vision aids
What are the disorders of refractive error?
Myopia (short sighted)
Hyperopia (long sighted)
Astigmatism (irregular corneal curvature)
Presbyopia (loss of accommodation with ageing)
What is the pathophysiology of open angle glaucoma?
The iriscorenal angle is open but there is blockage to drainage aqueous fluid through he trabecular meshwork which leads to raised IOP
What are the symptoms of open angle glaucoma?
Often none - discovered by optician
Visual field defect
What are the signs of open angle glaucoma on ophthalmoscopy?
High cup to disc ratio
May be haemorrhages
What is an arcuate field defect?
Nerve fibres travel horizontally from he fovea straight to the optic disc (papillomacular bundle)
Ganglion cell’s from outside that area have to arc around the papillomacular bundle in order to get to the disc (arcuate fibres)
Field defects in glaucoma often correspond tot he anatomical patterns - field defect will curve around the macula
