Ophthalmology Flashcards
sclera
white of the eye
conjunctiva
covers sclera
cornea
covers the iris
where is the lens
sits behind the iris
role of the lens
helps to refract light and focus it on the retina
changes shape to alter the focus distance (accommodation)
how is lens attached
attached to the ciliary body via suspensory ligaments
what composes outer layer of eye
sclera
cornea
what composes middle layer of eye (uvea)
iris
ciliary body
choroid
what composes inner layer of eye (retina)
macula
fovea
optic disc
roles of the ciliary body
control iris
shape the lens
secrete aqueous humour
circulation of aqueous humour
produced by ciliary body
circulates in posterior chamber (of anterior segment) and nourishes the lens
travels through pupil into anterior chamber (of anterior segment) and nourishes cornea
Absorbed at iridocorneal angle through trabecular meshwork at the canal of schlemm
anterior segment of the eye
in front of the lens
split into anterior chamber and posterior chamber
anterior chamber
- between cornea and iris
posterior chamber
- between the iris and suspensory ligaments
posterior segment of the eye
behind the lens
- contains the vitreous body (vitreous humour)
where is the blind spot
the optic disc
mneumonic to rememeber eye muscle innervation
LR6 SO4 AO3
topical Abx
chloramphenicol
ofloxacin
s/e of topical steroids for eyes
local
- cataracts
- glaucoma
systemic
- weight gain
- diabetes
- thinning skin
- gastric ulceration
- osteoporosis
List drug classes used in glaucoma Tx
prostaglandins beta blockers carbonic anhydrase inhibitors sympathomimetics parasympathomimetics
mechanism of topical prostaglandins
increase uveoscleral outflow
examples of prostaglandins
latanoprost
s/e of prostaglandins
increase eyelash length
segmental iris colour change
dehydrates periorbital fat
mechanism of beta blockers
decrease aqueous humour production
examples of beta blockers
timolol
s/e of beta blockers
systemic absorption
tiredness
mechanism of carbonic anhdrase inhibtors
decrease aqueous humour production
examples of carbonic anhydrase inhibitors
dorzolamide
acetozolamide
s/e of carbonic anhydrase inhibitors
short term use only - kidney damage
acetozolamide is oral and has systemic effects
examples of sympathomimetics
adrenaline
s/e of sympathomimetics
pupil dilation
mechanism of parasympathomimetics
increase uveoscleral outflow
examples of parasympathomimetics
pilocarpine
s/e of parasympathomimetics
pupil constriction
most common cause of endophthalmitis
post-cataract surgery
causative organism endophthalmitis
s. epidermidis
risk factors for AACG
hypermetropia (long-sightedness)
pupil dilation
presentation AACG
red eye n+v pain ++ fixed mid dilated pupil photophobia reduced visual acuity systemically unwell
characteristic visual field testing in AACG
arching
Mx AACG
IV Diamox (Acetozolamide) Mannitol Pilocarpine when IOP <50mmHg (constricts pupil)
causes of scleritis
connective tissue diseases - always investigate further
Mx scleritis
topical NSAIDs
violaceous hue
scleritis
cause of orbital cellulitis
extension from sinuses
preorbital cellulitis
little pain on eye movements
no reduced eye movements
no reduced visual acuity
Mx orbital cellulitis
IV Abx - ceftriaxone, fluclox + met
associations with episcleritis
gout
tiredness
Mx episcleritis
self-limiting - can give lubricants
give NSAIDS if not resolving
presentation anterior uveitis
red eye pain ++ photophobia hypoyon keratitic precipitates posterior synechiae
Mx anterior uveitis
Topical steroids (hrly, reduce gradually) + Mydriatics - tropicamide or cyclopentolate (dilates pupil and prevents posterior synechiae)
presentation bacterial keratitis
red eye pain ++ reduced visual acuity photophobia purulent discharge white corneal opacity seen with naked eye
Ix bacterial keratitis
corneal scrape form gram stain and culture
Mx bacterial keratitis
Topical Abx - ofloxacin
linear branching dendritic ulcer
herpes simplex corneal ulcer/keratitis
presentation adenoviral keratitis
bilateral
follows URTI
organism usually causing fungal keratitis
aspergillus
who gets fungal keratitis
farmers or gardeners
Hx of trauma from vegetation
organism causing protozoal keratitis
acanthomoeba
who gets protozoal keratitis
contact lens wearers
most common cause of viral conjunctivitis
adenovirus
Mx viral conjunctivitis
self-limitng +/- aciclovir if needed
Mx bacterial conjunctivitis
mild - mod: erythromycin
mod -sev: ofloxacin
Mx gonorrhoeal conjunctivitis
ceftriaxone + doxycycline
Mx chlamydial conjunctivitis
topical azithromycin and doxycycline
Mx allergic conjunctivitis
mild: cold compresses
mod: mast cell stabiliser + antihistamines
severe: + corticosteroid
seborrhoeic anterior blepharitis
++ dandruff
teepee sign
lashes themselves are unaffected
squamous anterior blepharitis
lashes affected - distorted
posterior blepharitis
inflammation of the meibomian glands
tarsal glands swollen and outpouching
risk factors for subconjunctival haemorrhage
blood thinners
elderly
truama
HTN
most common cause of vitreous haemorrhage
diabetic retinopathy
presentation vitreous haemorrhage
sudden painless unilateral loss of vision
red hue to vision
floaters/dark spots in vision
Mx vitreous haemorrhage
usually spontaneously resorbs
if dense - vitrectomy
Ix if retina cant be seen on ophthalmoscope e.g. due to bleed
b-scan ultrasound
causes of retinal detachment
primary - traction (ageing process - vitreous gel becomes more liquid)
secondary - trauma, post-inflammatory, CTDs, myopia
presentation retinal detachment
the 4 F's floaters flashes field loss fall in acuity
dense shadow that starts peripherally and progresses towards central vision
central vision lost if macula affected
Mx retinal tear
laser
Mx retinal detachment
external approach - scleral buckle
internal approach - vitrectomy
presentation CRAO
sudden painless loss of vision (counting fingers)
pale oedematous retina with cherry red spot
RAPD
Ix CRAO
need to rule out GCA - do ESR, CRP
fluorescein angiography
carotid artery imaging
Mx CRAO
prognosis v poor - aim is to dislodge the clot
ocular massage
IV acetozolamide
paper bag breathing
anterior chamber paracentesis
curtain coming down
amaurosis fugax
what is amaurosis fugax
transient CRAO
Mx amaurosis fugax
immediate referral !
presentation CRVO
sudden painless loss of vision
dark retina
RAPD
swollen disc
+/- neovascularisation
+/- macular oedema
Mx CRVO
no ischaemia - observe 3m
ischaemia - observe 4-6w
ischaemia + neovascularisation - panretinal photocoagulation
Ix CRVO
fluorescein angiography
optical coherance tomography (OCT)
risk factors for cataracts
down’s syndrome
long term steroid use
hypocalcaemia
diabetes
sub types of cataract
nuclear sclerotic
posterior subcapsular
cortical
mature
Mx cataracts
phaecoemulsification with intraocular lens implantation
what is given post op cataracts
steroids and chloramphenicol 4xday for 4w
complications post-op cataracts
retinal detachment
endophthalmitis
posterior capsule rupture
posterior capsule opacification
what is the characteristic finding of ARMD
drusen - calcium deposits due to axonal degeneration
major risk factor for ARMD
smoking
dry type ARMD
geographic atrophy of the macula
wet type ARMD
neovascularisation of the macula - eye grows new vessels to repair the damage from dry type
presentation dry type ARMD
gradual central vision loss
absent opic cup and abnormal branching patterns
Mx dry type ARMD
supportive - vision aids
stop smoking
blind registration
presentation wet type ARMD
sudden central vision loss
Mx wet type ARMD
anti-VGEF (ranibizumab) - prevents new vessel growth
what is open angle glaucoma
optic neuropathy and visual field loss due to clogging up of trabecular meshwork which blocks the drainage of aqueous humour
presentation open angle glaucoma
no symp till late - screened for by optometrists
increase cup to disc ratio (>0.4) - caused by loss of nerve fibres
peripheral vision loss
+/- raised IOP
Mx open angle glaucoma
prostaglandins beta blockers carbonic anhydrase inhibitors sympathomimetics parsympathomimetics
surgery - trabeculectomy
optic nerve lesion - visual field defect
unilateral field loss
causes of an optic nerve lesion
ischaemic optic neuropathy (arteritic or non-arteritic)
optic neuritis
optic chiasm lesion - visual field defect
bitemporal hemianopia
optic tract lesion - visual field defect
homonymous hemianopia
parietal optic radiation lesion - visual field defect
contralateral inferior quadrantanopia
temporal optic radiation lesion - visual field defect
contralateral superior quadrantanopia
visual cortex lesion - visual field defect
homonymous hemianopia with macular sparing
presentation of RAPD
when light is shone in eye - it dilates because there is a problem with the optic nerve communicating to the brain
what is horners syndrome
lesion in the sympathetic pathway
causes of horners syndrome
pancoast tumour
carotid/aortic aneurysms
congenital
presentation of congenital horners syndrome
will have diff coloured eyes
presentation horners syndrome
pupil constriction
ptosis
reduced ipsilateral sweating
holmes adie pupil
dilated
argyll robertson pupil
constricted pupil - associated with neurosyphilis
internuclear ophthalmoplegia
affected eye has impaired adduction
cause of internuclear ophthalmoplegia
issue with medial longitudinal fascia
presentation of internuclear ophthalmoplegia
(say R eye is affected)
fine on looking to the right side - eye can abduct fine
when looking to the left - right eye wont be able to, and left eye will have nystagmus
presentation CN III palsy
dilated pupil
down and out
painful third nerve palsy
aneurysm
presentation CN IV palsy
eye floats upwards
excylotorsion (head tils)
cause of CN VI palsy
increased ICP (pressed against petrous bone)
presentation CN VI palsy
convergent squint of affected eye
tropia
= manifest squint
phoria
= latent squint
esotropia/esophoria
eye is IN
you see OUTWARD movement at cover test
exotropia/exophoria
eye is OUT
you see INWARD movement at cover test
hypertropia/hyperphoria
eye is HIGHER
hypotropia/hypophoria
eye is LOWER
duanes retraction syndrome
hypoplastic IVth nerve
limited abduction and global retraction
browns syndrome
problem with SO, eye is elevated more than it should be
MX adult squint
non-surgical: temporary prisms, botox injection to temporarily paralse EOM
surgical: EOM surgery
amblyopia
lazy eye
impairment of vision without any clinically detectable abnormality of the eye or visual pathway
classification of amblyopia
ametropic
strabismic
anisometropic
stimulus deprivation
cause of an ametropic amblyopia
bilateral uncorrected refractive error
cause of a strabismic amblyopia
the squinting eye is being suppressed
cause of an anisometropic amblyopia
an unequal refractive error
cause of a stimulus deprivation amblyopia
congenital cataract or ptosis
Mx of amblyopia
occlusion therapy:
partial - patch for max 6h/d
total - atropine 1% into good eye
what is the problem in myopic people
short sighted
eye is too big so light focusses in front of the retina
type of lens needed for myopia
concave - takes power away from the eye so light focusses on the retina
what is the problem in hypermetropic people
long sighted
eye is too small so light focusses behind the retina
type of lens needed for hypermetropia
convex - adds power to the eye so light focusses on the retina
astigmatism
light doesnt focus evenly on the retina
presbyopia
natural degeneration in the lens that occurs with age
type of lens needed for presbyopia
convex - add power to eye
signs of diabetic retinopathy/maculopathy
microaneurysms
dot/blot haemorrhages
cotton wool spots
hard exudates
cause of cotton wool spots
swelling of nerve axons that appear fluffy and white against the retina
cause of hard exudates
yellow deposits on the retina due to plasma leakage from capillaries
stages of non-proliferative diabetic retinopathy
mild, moderate, severe
mild non-proliferative diabetic retinopathy
only microaneurysms present
at least one dot haemorrhage
moderate non-proliferative diabetic retinopathy
4 or more haemorrhages, but not in all 4 quadrants
severe non-proliferative diabetic retinopathy
implies a “busy fundus”
large amounts of haemorrhage and microaneurysm formation in all 4 quadrants
what characterises proliferative diabetic retinopathy
new vessel formation (VGEF)
Mx diabetic retinopathy
no retinopathy - screen 12m
mild non-proliferative - screen 12m
mod non-proliferative - screen 6m
severe non-proliferative - refer to ophthal
proliferative - urgent refer to ophthal
Mx proliferative diabetic retinopathy
retinal laser photocoagulation
grading of diabetic maculopathy
based on the location of the changes with respect to the fovea
- no maculopathy
- observable maculopathy - exudates between 1 and 2 disc diameters from the fovea
- referrable maculopathy - exudates < 1 disc diameter from the fovea
Mx observable maculopathy
resecreen 6m
Mx referable maculopathy
laser photocoagulation
stage I hypertensive retinopathy
silver or copper wiring
stage II hypertensive retinopathy
arteriovenous nipping
stage III hypertensive retinopathy
cotton wool exudates
flame and blot haemorrhages
stage IV hypertensive retinopathy
papilloedema
test to see how far back into eye a penetrating trauma goes
siedels test - fluorescein will be diluted as it leaks back through to the front of the eye
Mx corneal abrasion
chloramphenicol - as preventative to bacteria
usually take 24-48h to heal
sympathetic ophthalmia
a bilateral granulomatous uveitis due to trauma to one eye, thought to be autoimmune
Mx sympathetic ophthalmia
steroids and mydriatics
causes of alteration in colour of red reflex
aymmetrical camera shot
retinoblastoma
cause of opactiy of red reflex
cataract
causes of no/black red reflex
retinoblastoma
retinal detachment
Mx retinoblastoma
enucleation
Mx blocked nasolacrimal duct in kids
bathe and massage sac
most spontaneously resolve
Mx preorbital cellulitis
IV co-amoxiclav