Visual Loss Flashcards
Name four diseases that cause sudden visual loss
ARDM
Bleeding
Closed angle glaucoma
Detached retina
Briefly describe the blood supply to the eye
Major blood supply to the eye are the branches to the ophthalmic artery
- central retinal artery supplies inner 2/3rds of retina
- posterior ciliary artery supplies the nerve head
What are the signs and symptoms of central retinal artery occlusion?
Sudden painless visual loss RAPD Retina appears pale and oedematous Thread like vessels Cherry red spot
Why does the retina appear pale in CRAO?
Retina is normally transparent but becomes opaque when ischaemic
What is the cherry red spot?
Occurs at the fovea where the blood supply comes from the choroid so is not affected
What causes CRAO?
It is a type of stroke - carotid artery disease or embolus from the heart
Name two sub-types of CRAO
- branch occlusion
- amaurosis fugax
What is amaurosis fugax?
Transient painless visual loss like a black curtain, occurs for around 5 minutes then goes away
Where must all patients with amaurosis fugax be referred to?
Stroke Clinic
Name the three components of virchows triad
- endothelial damage (diabetes)
- abnormal blood flow (hypertension)
- hypercoaguable state (cancer)
What are the signs and symptoms of central retinal vein occlusion?
Sudden visual loss Haemorrhages Dilated tortuous veins Disc and macular swelling Cotton wool spots
Why is CRVO thought to occur?
As people age the artery gets stiffer but the vein remains pliable so the artery puts pressure on the vein and can occlude it.
What creates the cotton wool spot appearance?
Nerve fibre infarction
Name the investigation used to look at the retina specifically
OCT
What is the name for occlusion of the optic nerve head circulation?
Ischaemic Optic Neuropathy
How does ischaemic optic neuropathy present?
Sudden painless vision loss with a pale swollen optic nerve
What disease can cause ischaemic optic neuropathy?
Temporal arterities - posterior ciliary arteries become so inflamed that the lumen becomes occluded
Where can bleeding occur from in vitreous haemorrhage?
Abnormal vessels - ischaemia in diabetes or new vessel formation in vein occlusion
Normal vessels - bridging of a retinal tear
How will a vitreous haemorrhage present?
Loss of vision, floaters, loss of red reflex, haemorrhage may be seen on examination
How will a retinal detachment present?
Painless loss of vision, flashes and floaters, RAPD, visible tear
Why do patients with a retinal detachment see a flashing light?
Vitreous gets more watery with age and may collapse pulling in the retina - separation of the sensory retina and pigment epithelium means the patients sees a flashing light
How is vision lost in wet ARMD?
New vessels grow under the retina and leakage of fluid through the RPE and Bruch’s membrane causes build up of fluid and scarring
How will wet ARMD present?
Rapid central visual loss, distortion, haemorrhage (metamorphopsia), exudate
What causes angle closure glaucoma?
Increased pressure gradient causes iris to bow forward to obstruct the trabecular meshwork
