Loss of Vision Flashcards
Where does loss of vision occur in the eye?
posterior segment
What may appear in a histroy about loss of vision?
Unilateral/bilateral
Onset: sudden(seconds or hours)/gradual (over what period of time)
Type of visual loss: blurred/distorted/black
Any associated symptoms (pain, redness, discharge)
Good to know opthalmic history and social history - e.g. driving may be very importnt to someone
What is the assessment of a patient with loss of vision?
- History
- Examination
- Differential diagnosis
- Management
How do you examine a patient with vision loss?
Best corrected visual acuity - snellen chart
Opthalmascope
slit lamp
Fundal examination – direct ophthalmoscope and slit lamp & volk lens
Look for changes in the macula
ancilliary tests are used for loss of vision
What is the amsler chart?
detect vision problems resulting from damage to the macula (the central part of the retina) or the optic nerve
the Amsler grid is used to check whether lines look wavy or distorted, or whether areas of the visual field are missing.
ancilliary tests are used for loss of vision
How is colour vision tested?
ancilliary tests are used for loss of vision
How are visual field tests carried out?
Can be carried out manually or by using an automated perimeter
Uses a mobile stimulus moved by a perimetry machine
The patient indicates whether he sees the light by pushing a button
ancilliary tests are used for loss of vision
How is flurescein angiography carried out?
A medical procedure in which a fluorescent dye is injected into the bloodstream. The dye highlights the blood vessels in the back of the eye so they can be photographed. This test is often used to manage eye disorders
Watches the dyes passage throughout the eye
Dye passes through the arteries and fills capillaries and then returns through the veins
Use it less now as invasive and may develop an unpleasant allergic reaction
ancilliary tests are used for loss of vision
What is Optical Coherence Tomography?
Use this more now a days
Allows you to get a good look at the layers of the retina
a non-invasive imaging test
OCT uses light waves to take cross-section pictures of your retina and can see each of the retina’s distinctive layers
This allows your ophthalmologist to map and measure their thickness. These measurements help with diagnosis
What is sudden complete loss of vision (vascular) due to?
Central retinal artery occlusion
May be occluded by an embolism
And is very common to be thrown off from the carotid artery
Vision goes completely black
Lucky if the embolism breaks up and moves on
If doesn’t move on then becomes ischemic and infarcted
Yellow is swollen ischemic retina
Cherry red spot is due to the blood below and no nerves left
If there is sudden loss of vision what is it likely to be due to?
vascular
What is the management of loss of vision due to central retinal artery occlusion?
identify and treat risk factors (cardiovascular risk factors e.g. hypertension, AF - Atria not contracting properly and may develop clots)
Sudden complete loss of vision (vascular) may also be due to what else?
Central retinal vein occlusion
Central vein occlusion is likely to be occluded due to something compressing it form the outside like the hardening of the artery as they share the same space
Inflammation in the wall of the tube can reduce the lumen
May be something in the lumen
Hemorrhages all over the retina as blood cannot return so blood seeps out
In picture C showing fluid in the fovea
What is the treatment of sudden complete loss of vision due to central retinal vein occlusion?
identify and treat risk factors
intravitreal anti Vegf - makes the capillaries less leaky and the fluid disappears and vascular architecture returns to normal and vision does aswell
(stop the abnormal blood vessels leaking, growing and then bleeding under the retina. Vascular endothelial growth factor (VEGF) is a protein that promotes the growth of new blood vessels. It also makes the blood vessels more leaky. Anti- VEGF medicines stop the growth of these new blood vessels)
What is Anterior ischemic optic neuropathy?
Anterior ischemic optic neuropathy (AION) is a medical condition involving loss of vision caused by damage to the optic nerve as a result of insufficient blood supply (ischemia)
one of the causes of sudden complete loss of vision
What are the 2 types of anterior ischaemic optic neuropathy?
Arteritic: Giant Cell Arteritis
Non arteritic
What are the symptoms of anterior ischaemic optic neuropathy, giant cell arteritis?
loss of vision
headache
loss of appetite
scalp tenderness
pain on chewing - Arteries supplying the masseter effected so ischemia of the masseter during chewing
What is cataract and what symptoms does it cause?
gradual opacification of the lens
commenest cause is age and is the most common reaosn for blindness worldwide
Symptoms
loss of vision
dazzle/glare
What is the management of cataract?
surgery (phacoemulsification with intraocular lens implant)
Remove cloudy lens and replace with plastic implant
Done under topical anesthetic done on a out patient basis
What are the different classifications of glaucoma?
open or closed angle
chronic or acute
(In glaucoma, this passage or the drainage channel is blocked, either at its entrance or beyond. When the block is at the entrance it is called Closed Angle Glaucoma. When the blockage is not at the entrance, but beyond, somewhere inside, we call it Open Angle Glaucoma)
What are the symptoms of glaucoma?
assymptomatic
gradual loss of peripheral field of vision
What are the signs of chronic glaucoma?
raised intraocular pressure
visual field defects
optic disc damage - enlarges
What are the symptoms of AMD?
progressive loss of central vision
distorsion
painless
What are the signs of AMD?
distorsion on amsler chart
drusen - yellow deposits under the retina. Drusen are made up of lipids, a fatty protein. Drusen likely do not cause age-related macular degeneration (AMD). But having drusen increases a person’s risk of developing AMD
pigment epithelial changes
What is Dry Age Related Macular Degeneration?
Red is blood
Pigment epithelium essential
Yellow sports are common
Cells of the pigment epithelium move away and are separated from the choroid where they get their nutrition so become unwell and atropihc
(image carries onto next slide)
atrophy
What investigations can be carried out for Wet (Neovascular) Age Related Macular Degeneration?
OCT
Flurescein angiography
What is the management of Wet (Neovascular) Age Related Macular Degeneration?
intravitreal antivegf - treat a number of eye conditions that cause new blood vessel growth or swelling under the macular area of your retina. A group of medicines which reduce new blood vessel growth (neovascularisation) or oedema (swelling)
low vision aids
registration
What are the signs of diabetic retinopathy?
microaneurysms
retinal haemorrhages and exudates
neovascularisation (disc/retina)
Occlusion of capillaries leading to ischemic retina
Exudate as capillaries become leaky and fluid may leak out into the retina
As the retina becomes ischemic it produced EFGF
Stimulates growth of new vessels usually coming from the disc
Lots of very abnormal blood vessel stimulated by the ischemic retina
Can get massive bleeds into the vitreous
What investigations can be carried out for diabetic retinopathy?
fluerescein angiography - look for new vessles at the disc
OCT - fluid leaks into retina
