Visual Loss and Blindness Flashcards
What are some causes of sudden vision loss?
Retinal vein/artery occlusion, vitreous haemorrhage, retinal detachment, closed angle glaucoma, optic neuritis, stroke, wet type age related macular degeneration
What are the symptoms of central artery occlusion?
Painless sudden visual loss, relative afferent pupil defect, pale oedematous retina, thread-like retinal vessels
What are some causes of retinal artery occlusion?
Carotid artery disease, emboli form heart (rare)
Can branches of the retinal artery/vein become occluded?
Yes = also cause sudden visual loss
What is amaurosis fugax?
Transient central artery occlusion = urgent referral to stroke clinic
What are the symptoms of amaurosis fugax?
Transient painless visual loss = lasts 5 mins with full recovery, “like curtain coming down”
No abnormal signs on examination
What are some associations of central vein occlusion?
Endothelial damage (diabetes), abnormal blood flow (hypertension), hypercoagulable state (cancer)
What are the symptoms of central vein occlusion?
Sudden visual loss (variable), retinal haemorrhage, dilated tortuous vein, disc and macular swelling
What causes ischaemic optic neuropathy?
Occlusion of the optic nerve head circulation = posterior ciliary arteries become occluded causing ischaemia
What is an association of ischaemic optic neuropathy?
Giant cell arteritis = medium/large sized arteries are inflamed, lumen of artery becomes occluded due to gross thickening of artery wall
What is needed to prevent blindness due to ischaemic optic neuropathy?
Prompt diagnosis and immediate treatment
What are the symptoms of ischaemic optic neuropathy?
Sudden severe visual loss, irreversible blindness, swollen optic nerve
What are some symptoms of giant cell arteritis?
Temporal headache, jaw claudication, scalp tenderness, tender/enlarged scalp arteries, amaurosis fugax, malaise
What are some causes of abnormal vessels?
Retinal ischaemia in diabetes, retinal vein occlusion causes abnormal fragile new blood vessels to form
What is a vitreous haemorrhage?
Haemorrhage of blood into areas in and around the vitreous humour = located between lens and retina
What are the symptoms of vitreous haemorrhage?
Sudden loss of vision, haemorrhage, loss of red reflex,
What are the symptoms of retinal detachment?
Painless sudden loss of vision, sudden onset of flashes/floaters, relative afferent pupil defect, tear seen on ophthalmoscopy
Why is there sudden onset of flashes/floaters in retinal detachment?
Due to mechanical separation of sensory retina from the retinal pigment epithelium
What is the most common cause of blindness in the west in patients > 65?
Age related macular degeneration
What are some risk factors for age related macular degeneration?
Increasing age, smoking, positive family history, poor nutrition
What are the two kinds of age related macular degeneration?
Wet and dry
What occurs in wet type macular degeneration?
New blood vessels grow under retina = leakage causes build up of blood and eventual scarring
What are the symptoms of wet type macular degeneration?
Rapid sudden central visual loss, distortion, haemorrhage/exudate
What is glaucoma?
Progressive optic neuropathy = results in optic nerve damage and visual loss
What occurs in closed angle glaucoma?
Aqueous humour encounters increased resistance through iris/lens channel
What does the increased pressure gradient in closed angle glaucoma cause?
Causes peripheral iris to blow out = obstructs trabecular meshwork
How is blindness prevented in closed angle glaucoma?
Need to lower intra-ocular pressure with drops/oral medication = acute onset is ophthalmic emergency
What are the symptoms of closed angle glaucoma?
Painful red eye, sudden visual loss, headache, nausea, vomiting, cloudy cornea, dilated pupil
What are some features of gradual visual loss?
Usually bilateral, often asymmetrical, may present early with reduced visual acuity or late with decreased field
What are the causes of gradual visual loss?
Cataract, dry type age related macular degeneration, open angle glaucoma, diabetic retinopathy
What are cataracts?
Cloudiness of the lens
What causes cataracts?
Abnormal changes in lens proteins (crystallins) result in their chemical/structural alteration = leads to loss of transparency
What is the number one cause of preventable blindness worldwide?
Cataracts
What are some associations of cataracts?
Age, congenital, trauma, diabetes, steroids
What are the different types of cataracts?
Nuclear, subcapsular, Christmas tree (polychromatic)
What are some symptoms of cataracts?
Gradual decline in vision (hazy/blurred) that can’t be corrected with glasses, may get glare (disabling at night when driving)
What is the management for cataracts?
Surgical removal with intra-ocular lens implant if patient is symptomatic
What are the symptoms of dry type age related macular degeneration?
Gradual decline in vision, central vision missing (scotoma), build up of waste products below RPE (Drusen sign), atrophic patches of retina
What is the treatment for dry type age related macular degeneration?
Supportive = low vision aids (e.g magnifiers)
What is the main complaint in refractive errors?
Eye can’t focus on image = need glasses to correct
What are the types of refractive errors in the eye?
Myopia = short sighted Hypermetropia = long sighted Astigmatism = usually irregular corneal curvature Presbyopia = loss of accommodation with ageing
What is strange about open angle glaucomas?
They often have no symptoms
What are some signs of an open angle glaucoma?
Cupped disc, visual field defect, may have high intra-ocular pressure
