opthalmology Flashcards
which part of the eye produces aqueous humour
cilliary body
which cranial nerve palsy makes the eye go down and out when looking forward
oculomotor (cn3)
which cranial nerve palsy makes the eye turn upwards and inwards when looking forward
trochlear (cn4)
which cranial nerve palsy makes the eye turn inwards when looking forward
abducens (cn6)
where abouts is the angle that gets blocked in acute angle closure glaucoma
where the trabecular meshwork is where the iris meets the cornea in the anterior chamber
what is the function of the aqueous humour
to nourish an hydrate the eye
where is the anterior chamber located
between the cornea and the iris
where is the posterior chamber located
between the iris and the lens
where is the viterous chamber located
behind the lens
what is the function of the choroid
essentially a spongey vascular layer that helps to provide nutrients to the outer layer of the retina and contains pigment to absorb excess light
what is the function of cilliary body
pupillary constriction / dilatation
produces aqueous humour
what is the function of the lens
to focus (refract) light from the pupil onto the retina
what is the function of the conjunctiva
a moist clear membrane that covers the sclera, it protects and lubricates the eye ball
where are most cone cells found
fovea
what is the function of the fovea and where is it found
found at the centre of the macula, produces a highly focused quality image to send to the brain
what is the function of the iris
to control the amount of light that is able to enter the eye
function of cone cells
colour vision
better in high light levels
high spatial acuity
function of rod cells
night vision
better in low light levels
low spatial acuity
pathophysiology of primary open angle glaucoma
slowly increasing resistance of trabecular meshwork to outflow of humour = gradually increasing IOP over time = asymptomatic for ages / fluctuating onset of symptoms
symptoms of primary open angle glaucoma
asymptomatic / incidental finding by optometist gradual loss of peripheral vision nasal scotomas / tunnel vision halos around lights at night fluctuating pain (not always) headache
findings on fundoscopy in primary open angle glaucoma
optic disc cupping - meaning the indent in the optic disc (optic cup) is more than 0.7
pale optic disc from optic atrophy
investigations to do in suspected primary open angle glaucoma
- fundoscopy
- assess visual fields with automated perimetry
- use slit lamp and dilate pupil to look for signs of optic nerve damage and assess baseline
- goldmann applanation tonometry to assess intra ocular pressure
1st line treatment of primary open angle glaucoma
latanoprost drops - prostaglandin analogue to increase uveosacral outflow
how does timolol drops work
beta blocker - decreases production of aqueous
how does latanoprost drops work
increases uveosacral outflow
how does pilocarpine drops work
antimuscarinic that acts on the parasympathetic fibres to induce pupillary muscle constriction = pain relief and opens the angle to allow some drainage of humour
how does oral / iv Acetazolamide work
reduces aqueous production by inhibiting carbonic anhydrase
what investigations should you do in suspected acute angle closure glaucoma
- goinoscopy - examines the anterior chamber angle
- slit lamp examination
- applanation tonometry to measure IOP
findings on examination in acute angle closure glaucoma
hard, red eye
fixed dilated non reactive pupil
corneal oedema
what should you give someone in the primary care setting pre-hospital with suspected acute angle closure glaucoma
- pilocarpine eye drops 2% if blue eyes 4% if brown eyes
- acetazolamide 500mg po stat
- antiemetic + analgesia
presentation of acute angle closure glaucoma
severely painful, red, hard eye haloes around lights worse in dark reduced visual acuity (blurred vision) semi dilated non reacting pupil corneal oedema - dull / hazy N+V
which drugs can precipitate acute angle closure
anticholinergics eg oxybutinin
pupil dilating eye drops eg atropine
what is seen on fundoscopy in both types of ARMD
drusen (yellow spots of lipids on the retina)
pathophysiology in ARMD
both: drusen formation from lipid deposits and degeneration of retinal photoreceptors
wet: get neovascularisation causing new vessels to leak fluid or haemorrhage into the retina causing retinal oedema = faster degeneration of vision
describe the vision loss in ARMD
central scotoma / slow central loss of vision / loss of visual acuity of up close things / deterioration in night vision
symptoms of ARMD
central scotoma, declining night vision, distortion of straight lines, seeing things flickering / flashing lights
loss of peripheral vision and haloes around lights
acute glaucoma
loss of central vision / central scotoma and blurring / waving of lines
ARMD
generalised reduction in visual acuity and starbursts around lights at night time
cataracts
key sign on examination in cataracts
loss of red reflex - will be white or grey instead
symptoms of cataracts
reduced visual acuity
things may go yellowy or brown in colour
starbusts around lights at night
asymmetrical as both lenses affected differently
treatment of cataracts
if not an issue then leave it alone
if reduced visual acuity severe then surgery
findings on fundoscopy in cataracts
normal
complications following cataracts surgery
- posterior capsule opacification
- retinal detachment
- endopthalmitis –> inflammation of aqueous and / or viterous humour
name a cause of endopthalmitis
complication of cataracts surgery
