Visual Defects and Repair Flashcards
What are the 6 main symptoms of visual loss?
1) Blurred/ out of focus vision
2) Glare
3) Distorted vision
4) Things look pale
5) Shadow
6) Floater
What are the 2 possible problems causing blurred vision?
1) Refractive problem - to do with cornea, lens, shape of eye
2) Macular problem
What is glare?
Difficult seeing in bright light - eg. low sun or fluorescent light at supermarkets - vision may be good otherwise
Glare is usually due to a problem with what?
Cornea or the lens - often due to cataract
What 4 conditions can lead to distortion of vision, what structure do they all affect?
All conditions affecting the retina:
1) Wet macular degeneration
2) Macular hole
3) Macular pucker
4) Retinal detachment
The symptom of things looking paler is due to what 2 types of conditions?
1) Optic nerve disease - optic neuritis or compressive optic nerve disease
2) Conditions affecting the retina - wet macular degeneration, central serous retinopathy
If a field defect is homonymous what is affected?
Its a defect of the visual pathways
If a field defect is not homonymous it is likely to be a defect of one of which 2 structures?
1) Retina
2) optic nerve
What is a floater and what 3 conditions can it be due to?
Opacity in the vitreous Can be due to: 1) Vitreous syneresis 2) Posterior vitreous detachment 3) Vitreous haemorrhage
What is a cataract?
Opacity of the lens - get yellowing of the lens
This is a common ageing change
How can you examine for cataract?
Examine against red reflex or using a slit lamp
What are the symptoms of cataract?
The symptoms depend on the type of cataract and can include: blurred vision, glare, change in refraction
These can also be asymptomatic - it is difficult to judge the effect on vision from examination
What is the vascular supply to the retina?
Inner retina - from retinal vessels
Outer retina requires diffusion from the choroid - the retinal pigment epithelium maintains the environment of photoreceptors
What is involved in removing waste products from the cones and rods, what does reduced function of this structure lead to?
Retinal pigment epithelium removes waste products from rods and cones
Reduced function leads to drusen - deposits of waste products at the macula
What are the 3 signs of dry age related macular degeneration (ARMD)?
1) Drusen
2) RPE pigmentation
3) RPE atrophy
What are the symptoms of dry ARMD?
Loss of small area of retina leads to severe visual loss
Reading vision is particularly affected but early stages are often asymptomatic
Sudden deterioration of dry ARMD may indicate development of what?
Wet ARMD
There is no effective medical treatment for dry ARMD but what 4 pieces of advice can be given to patients?
1) Stop smoking
2) Wear dark glasses to protect from bright sunshine
3) Dietary changes/ supplement
4) Low visual aids
What is the treatment for cataracts?
Surgery: Phacoextraction with lens implant
What is Biometry used for in cataract surgery?
To decide on the power of the lens implant
Under what anaesthetic is phacoextraction with lens implant (cataract surgery) performed, will the patient experience any pain afterwards?
Usually under local anaesthetic
Eye may feel swollen and gritty afterwards but not painful
How long does phacoextraction with lens implant take?
10 mins
What is the post operative treatment for phacoextraction with lens implant?
Topical steroid for 2 weeks, review at 2 weeks if no problems, new glasses after 2 weeks
What are the 4 risk factors for carotid artery disease?
1) Hypertension
2) Smoking
3) Diabetes
4) High cholesterol
What are the 3 possible causes of central retinal artery occlusion (CRAO)?
1) Embolic: carotid artery disease (most common cause)
2) Embolic: heart disease (valve disease)
3) Giant cell arteritis
How can carotid artery disease be treated? 3
1) Reduce risk factors
2) Antiplatelet agents
3) Carotid endarectomy if greater than 70% stenosis
Why is important that carotid artery disease causing CRAO is treated?
There is a risk of further emboli to eye or brain
Giant cell arteritis can cause visual loss due to which 2 conditions, is either treatable?
1) Central retinal artery occlusion (CRAO)
2) Anterior ischemic optic neuropathy (AION)
Neither is treatable
Neither condition causing visual loss due to giant cell arteritis is treatable, why is urgent treatment of giant cell arteritis required if suspected (in regard to vision)?
Because there is a high risk of CRAO or AION to other eye
How can a diagnosis of giant cell arteritis be confirmed?
Temporal artery biopsy
How can a diagnosis of carotid artery disease be confirmed?
Doppler of carotids
What is metamorphosia?
A type of distorted vision
Metamorphosia is a symptom of disruption of what structure in the eye?
Distortion of the retina
What are the 4 differential diagnoses with symptoms of distorted vision?
1) Wet macular degeneration
2) Macular hole
3) Macular pucker
4) Retinal detachment
What is Wet age related macular degeneration (ARMD)?
Get a choroidal neovascular membrane beneath the retina
Causes a rapid loss of vision and is a common cause of severe visual loss
Can Wet ARMD be treated?
Effective treatment is now available
How is Wet ARMD treated?
Intravitreal injection of antiVEGF
VEGF (vascular endothelial growth factor) stimulates growth of choroidal neovascular membrane (CNM)
AntiVEGF binds to VEGF and prevents it acting on CNM
Visual loss can then be reversed
How does a full thickness macular hole affect vision?
Only affects central vision but will probably deteriorate if no treatment is given - there is a 10% risk of the other eye being affected
What is the treatment for macula hole?
Surgery - performed under local anaesthetic and need to posture face looking down for a period after the operation
What are the 4 disadvantages of an operation to treat macula hole?
1) Risk of not closing the hole is about 10%
2) Risk of serious complication leading to loss of vision is 1%
3) Will develop cataract
4) Visual recovery is variable
What is macular hole?
Literally a hole in the retina at the macula
