Visual loss and blindness Flashcards
What are the 7 causes of sudden visual loss?
- Vascular aetiology (retinal artery/vein occlusion)
- Vitreous haemorrhage
- Retinal detachment
- Wet ARMD
- Closed angle glaucoma
- optic neuritis
- Stroke
Describe the arterial supply of the eye
Internal carotid artery gives off branches, ophthalmic artery is the main supply to the eye
What are the branches of the ophthalmic artery?
Posterior ciliary, supply the optic nerve head
Central retinal artery, supply inner 2/3rds of retina
What are the symptoms of central retinal artery/vein occlusion ?
Sudden visual loss
Painless
What are the signs of central retinal artery occlusion?
RAPD
Pale oedematous retina
Thready retinal vessels
Describe branch retinal artery occlusion
Only part of retina will look pale
Half of visual field compromised
Describe amaurosis fugax symptoms?
Transient painless visual loss
Lasts 5 minutes with full recovery
When can haemorrhages occur in the eye?
Abnormal blood vessels- wet ARMD, diabetes
Normal vessels -Bridging a retinal tear
What are the causes of central retinal vein occlusion?
Carotid artery disease
Emboli from heart- endocarditis?
What are the signs of a central retinal vein occlusion?
- retinal haemorrhages
- dilated torturous veins
- disc swelling and macular swelling
- edge of disc may be swollen
- cotton wool spots
- oedematous macula
What is ischaemic optic neuropathy?
Posterior ciliary arteries become occluded, infarction of optic nerve head
What can cause ischaemic optic neuropathy?
GCA
What are the symptoms of ischaemic optic neuropathy?
Sudden visual loss
Irreversible blindness
What are the signs of ischamic optic neuropathy?
Swollen optic nerve
Describe symptoms of a vitreous haemorrhage
Loss of vision
Floaters- flu, cobwebs, black dot
What are the signs of a vitreous haemorrhage?
Loss of red reflex
-media not clear, may look black, brown
May see haemorrhage on fundoscopy
What is important in vitreous haemorrhage?
Fina a cause
What are the symptoms of retinal detachment?
Painless loss of vision
Sudden onset of flashes/floaters (mechanical separation of sensory retina from retinal pigment epithelium)
What are the signs of retinal detachment?
RAPD
What can cause retinal detachment?
Age makes vitreous more liquidy- this can pull on retina and tear it
What are the factors related to ARMD?
Smoking, FHx, poor nutrition
Describe wet ARMD?
New blood vessels grow under retina from the choroid, leakage causes build up of fluid/blood and eventually scarring
What are the symptoms of wet ARMD?
Rapid central visual loss
Distortion (metamorphosia- straight lines may appear linked)
What are the signs of wet ARMD?
Haemorrhages/exudate (protein leaked and precipitated into retina)
What is the amsler test?
Grid- cover up one eye and describe what you see
What are the symptoms of dry ARMD?
Gradual visual loss
What is the only modifiable risk factor in glaucoma?
High IOP
Describe closed angle glaucoma?
- aqueous humour encounters increased resistance through iris/lens channel
- increased pressure gradient causes peripheral iris to bow forward, obstructing trabecular meshwork- pressure increases
- may be acute (ophthalmic emergency)
Describe the symptoms of acute closed angle glaucoma?
Painful, red eye/sudden visual loss/headache/nausea/vomitting
Describe the signs of acute closed angle glaucoma?
Red eye, cloudy cornea, dilated pupil
What causes pupil dilation in acute closed angle glaucoma?
Ischaemia has rendered it non-functional
What are the common causes of gradual visual loss?
Cataracts Dry ARMD Refractive error Open angle glaucoma Diabetic retinopathy
Describe cataracts?
Cloudiness of the lens- abnormal changes in lens proteins (crystalline) result in their chemical and structural alteration, leading to loss of transparency
What are the causes of cataracts?
Age Congenital e.g. Intra-uterine infection Traumatic Metabolic (diabetes) Drug induced
What are the 4 types of cataract?
Nuclear cataract
Posterior subcapsular cataract
Polychromatic cataract
Congenital cataract
Which type of cataract is particularly visually disabling?
Posterior sub capsular cataract
Describe a congenital cataract?
Dense centre- no brown/green colour
What are the symptoms of cataract?
Gradual decline in vision (hazy/blurred) that cannot be corrected
Glare (at night when driving)
Describe dry ARMD?
Build up of drusen inner retina (by-products of epithelial cells) stops nutrition diffusing to retina from choroid.
The retina gets further away from nutrition and thins
What are the symptoms of dry ARMD?
Gradual decline in vision
Central vision missing (scotoma)
What are the signs of dry ARMD?
Drusen= yellow-white flecks
Atrophic bathes of retina (appears bright red as you can see choroidal vessels)
What is myopia?
Short-sightedness
What is hypermetropia?
Long-sightedness
What is astigmatism?
Irregular corneal curvature
What is presbyopia?
loss of accommodation with ageing
Describe open angle glaucoma?
Something stopping drainage through trabecular meshwork
What are the signs of closed angle glaucoma?
Cupped disc
Visual field defect (Arcuate)
May/may not have high IOP
