L34 - visual defects 2 Flashcards
questions to ask about visual field
- do things look distorted?
- is there a shadow?
- does the shadow move?
blurred vision
- out of focus
- no distortion or shadows
- refractive problem
glare
difficulty seeing in bright light
- corneal or lens problem
- may be due to cataracts
distortion of vision
- things look wavy, jumbled up
- lines not straight
- condition affecting retina
things look pale
- look dark / less colour
- optic nerve disease
- affects retina
floater
- smudge
- movement
- degeneration of the vitreous (bits of it liquefy)
where is the defect if it is homonymous
defect of visual pathway
where is defect it is is heteronymous
retinal
optic nerve
What are the 2 formal measurements of visual fields?
- Field testing by confrontation
2. Field testing by machine analyser
field testing by confrontation
- doctor and patient opposite each other with opposing eyes covered
- use finger to try and compare their visual field to your visual field
machine analyser
Humphrey Field Analyser
- A bowl a patient rests their chin on
- Spectacle lens to correct for their refraction
- A fixation point (dot in the middle)
- Dots of light come up at
- Patient presses button if they see light
cataracts
An opacity or discoloration of the lens
*lens matures from the inside out
blood supply to the retina
choroid (underneath sclera) and retinal vascular supply;y
symptoms of cataracts
- gradual onset
- depend on type: blurred vision, glare, change in refraction
where does the choroid supply
outer 2/3
where does the retina vascular supply
inner 1/3
signs of ARMD (age related macular degeneration)
- drusen
- RPE pigmentation
- RPE atrophy
What are the symptoms of dry ARMD?
- gradual deterioration (early stages are often asymptomatic)
- reading vision is affected
surgery in cataracts
phacoextraction with lens implant
On fundoscopy, a paler retina with spots of red and a pronounced redness of the fovea is indicative of what condition?
Indicative of CRAO
CRAO
central retinal artery occlusion
causes of CRAO
- carotid artery disease
- heart disease
- giant cell arteritis
Giant cell arteritis causes visual loss due to which 2 conditions?
CRAO or AION
not treatable, urgent treatment required
AION
anterior ischaemic optic neuropathy
What are the main conditions which affect the retina?
- ARMD
- wet macular regeneration
- macular hole / pucker
- retinal detachment
What occurs in wet ARMD?
- newly immature blood vessels in choroid grow towards outer retina
- leak fluid within or below the retina
glaucoma
damage to optic nerve related to high pressure in the eye
VEGF stimulates the growth of what?
choroidal neovascular membrane
VEGF
vascular endothelial growth factors
giant cell arteritis / temporal arteritis
- systemic vasculitis of unknown cause
- headache
- malaise
- visual loss
metamorphopsia
visual defect that causes linear objects, such as lines on a grid, to look curvy or rounded
how does the choroid supply the retina
diffusion
Dry ARMD
- built up of waste products
- photoreceptors lost and retinal pigment epithelium damaged
- sudden deterioration may indicate wet ARMD
drusen
fatty deposits in the eye
how to treat wet ARMD
anti-VEGF prevent growth of choroidal neovascular membrane - visual loss can be reversed
