Revision Tutorials (important) Flashcards
what does a teardrop iris suggest
corneal injury- teardrop will point to it
how does corneal injury affect vision
changes corneal shape
what must you worry about in corneal penetrating injuries
retinal detachment symptoms- decrease in pressure in anterior chamber causes vitreous to move forwards
what must you always ask to check for retinal detachment
floaters that persist
flashes
what hypersensitivity reaction is sympathetic ophthamloplegia
type II
how can a head injury affect vision
visual cortex (haemorrhage/ injury) = cortical blindness lens dislocation (vision reduced, increased red reflex) retinal scarring
what should you assume in pupil deformities
perforating injuries until proven otherwise (may be normal)
what is the seidels test
flood eye with fluoroscene to look for penetrating injury, aqueous coming out of eye will dilute the fluoroscene
what is a perforating eye injury
will go in and out of eye
what eye condition results from infection under contact lenses
Acanthamoeba keratitis
what is the advice for people who wear contacts
dont sleep, swim or shower in them
dont wear for more than 5 days a week
dailys are safer than monthlys
when does it hurt to move your eye
inflammation at the back of the eye
what is affected to causes changes in colour
optic nerve
what is affected to causes changes to visual field
retina
what does corneal reflection show
position of eyes when looking at same point- squints
light high in eye then eye position low
what is a tropia
one eye looking straight, one eye squint
what is the cover test
covering eye alternately whilst looking at a fixed point, individual eye should not move when the other is covered, if it does then squint in that eye
what are the types of tropia
esotropia- outward movement of eye = eye turned in
exo-eye turned out (inward movement in cover test)
hyper- eye upward
hypo- eye downward
do you keep your glasses on for the cover test
yes
what is the fixing eye
eye that doesnt move in the cover test
can squints alternate between eyes
yes but will only be in one eye at a time
what will give you horizontal double vision
inward/outward position of eye
what will give you vertical double vision
eye upward/ downward position
how do you asses occular motility
take glasses off, head still, follow torch with eyes, sclera should disappear where eye is looking (position of gaze)
visible sclera= weak muscles
what is the primary position of the eye
looking forward
how do you test each eye muscle
up= SR/IO up and in= IO medial= medial rectus down and in= SO down= SO/IR down and out= IR lateral= LR up and out= SR
where will double vision be the worst
where the muscle is the weakest
what causes a horizontal diplopia
eso/exo tropia
what causes a vertical diplopia
hyper/hypo tropia
what diplopia will a 6th nerve palsy create
horizontal
what is seen in a 3rd nerve palsy
MR, SR, IR, IO weakness
ptosis
pupil dilated
eye goes out and down in III nerve palsy as LR strongest muscle
what is seen in a 4th nerve palsy
eye will elevate (as SO weak)
why can nerves 3,4 and 6 all be affected at the same time
as all in cavernous sinus
what are the most common causes of squint in the elderly
microvascular: diabetes, hypertension, hyperlipidaemia, age, hypercoagulability
what nerve is at risk from whiplash injuries
4th (exits brain posteriorly)
what causes a squint in children
raised ICP, shunt, viral, trauma
what is visual acuity
the resolving power of the eye, ability to differentiate between two points
how far away should a snellen chart be
6 meters
how do you document a snellen chart result
meters away/ line of letters - how many you got wrong u/a unaided \+PH with pinholes \+ glasses
e.g. 6 (meters)/ 9 -1
what can pinholes tell you
if vision blurring is down to needing glasses/ new prescription
in your osce do you leave glasses on or off to do visual acuity
with glasses
can use pinholes use glasses to see if vision changes are just because they need glasses or a new prescription
what happens if the patient can see the top letter at 3 meters
test if they can count fingers right infront of face (CF)
if not if they can see hand waving (HM)
if not if they can see light (POL)
if not= no perception of light (NPOL)
what does close vision test
macula function
hold page at natural reading distance
smaller the number smaller the writing they can read
how do you test the vision of babies/ children
babies differential vision - barcodes that get finer and finer
children shapes/ toys that they can point to
why do you look into the distance to get pupils
so they dont accommodate to the light
what does a swinging light test for
RAPD
what does fluoroscein angiography test for
ocular circulation
what happens to the macular is wet ARMD
is elevated by exudative fluid produced by a subretinal choroidal neovascular membrane
what is the treatment for wet ARMD
intravitreal antiVEGF injections (only works in early cases)
what can happen in neovascularisation of the optic disc
sight threatening
vitreous haemorrhage
sudden visual loss
what is the treatment for optic disc neovascularisation
pan retinal laser photocoagulation (reduces hypoxic drive)
what happens to the optic disc in glaucoma
enlargement of the optic cup as nerve fibres are lost in the neuroretinal rim
may be bayonetting of the vessels as the follow the deepened disc contour
what is a normal cup to disc ratio
0.2-0.6
what should a normal optic disc look like
neuroretinal rim (nerve fibre layer) is pink and even in thickness
what is the cup to disc ratio in advanced glaucomatous cupping
0.9-1
what is temporal cresent pigmentation found in
glaucoma
what are the features of papilloedema
obscured disc margins, optic cup is lost, may be haemorrhages on the elevated optic disc surface or margin, dilated vessels at the disc
