Gradual Visual Loss Flashcards
how may gradual visual loss present
often early with reduced visual acuity or late with decreased field
typical causes
cataract
Dry ARMD
refractive error
glaucoma (open-angle)
diabetic retinopathy
hypertension
cataract
any opacity in the lens is called a cataract
risk factors for cataract development
- Most cataracts are age related
- In children, many are genetic
- Cataracts occur early in: DM, steroid use, high myopia a
cataracts in DM
- Develop earlier in people with DM. Normoglycaemia may reverse.
what must be measured when a cataract is found
fasting plasma glucose to exclude DM
what is the 1y cause of preventable blindness worldwide
cataracts
red reflex in cataracts
- in immature cataracts the RR still appears
- if the cataract is dense there is no RR
what are cataracts classified by
lens appearance
nuclear cataracts
- changes the lens refractive index and is common in old age
- gradual clouding of central portion of lens - the ‘nucleus’
how do nuclear cataracts often occur, adn what is a characteristic sign of this
blunt trauma - stellate morphology
subcapsular cataract
just deep to lens capsule in the visual axis
what are subcapsular cataracts often associated with
- STEROID use, DM and hypermetropia
- allopurinol use may be indicated
anterior and posterior polar cataracts
Anterior and posterior polar cataracts are localized, commonly inherited and lie in the visual axis. Round mass in the central portion of the lens.
polychromatic (Christmas tree) cataracts
consist of highly reflective, iridescent corneal crystals of different colours
cortical cataract
start in the periphery and move into centre
presentation of a cataract
- blurred vision, unable to be corrected by glasses
- halos surrounding lights
how do unilateral cataracts present
often unnoticed, loss of stereopsis (depth perception) affects distance judgement
how do bilateral cataracts present
gradual loss of vision, dazzle (especially in bright light), monocular diploplia
how do cataracts present in children
squint, loss of binocular function or a white pupil or nystagmus/amblyopia
management of cataracts
surgical removal with intra-ocular lens if the patient is symptomatic
dry ARMD features
called dry as there is no fluid in the macula
central vision is missing (‘scotoma’)
drusen in macula and degenerative changes (atrophic patches ) in the macula
drusen
- signify optic nerve head axonal degeneration - abnormal axonal metabolism leads to intracellular mitochondrial calcification
- some axons rupture and mitochondria are extruded into the extra-cellular space below RPE
- calcium is deposited
progression of dry ARMD
progresses slowly, may progress to wet
management of dry ARMD
there is no cure, treatment is supportive with low vision aids eg magnifiers
polychromatic cataract
