summary factoids Flashcards
describe the circulation of aequous
ciliary body posterior chambre pupil norishes cornea aqeuous reabsorped into scleral venous sinus (canal of schlemm) at iriocorneal angle (angle involved in glaucoma)
what does the inferior oblique do
when in addction, IO can only elevate
what does the superior oblique do
when in adduction, SO can only depress
which muscles can do pure elevation
SR and IO,
which muscles can do pure depression
SO and IR
what is the shape of the orbit
pyramidal with apex at optic canal posteriorly, base is anteriorlateral
what is the infraorbital nerve responsible for?
sensation in the mid face region
what does orbicularis oris do
external muscle of eye - CN7
orbital and palpebral
orbital orbicularis oris
tight closure of eye
orbicularis palpebral
dircectly on eyelid, gentle closure of eye
what does orbital septum do
helps prevent spread of infection from superfiical to deep
a tough layer of connective tissue
what is the tendon of LSP
attaches to tarus
mullens muscle (widens eye)
elevates upper eyelid
what does the tarsal gland do
secretes lipids + stops tears from flowing over eyes
describe the lacrimal apparatus
lacrimal gland > lacrimal fluid > medial angle > little hole > caniculi > lacrimal sac > nasolacrimal duct > nasal cavity > inferior nasal meatus > runny nose
what is the corneal reflex
blinking
sensory afferent limb of corneal reflex
sensory afferent via CN VI branches -> trigemial ganglion > CN V > pons
motor efferent limb of corneal reflex
AP conducted by CN VII to eyelid part of orbicularis oris
what is the vestibuloocular reflex
turns eye in opposite direction to head movement
stabilises gaze on object
what is the occulocardiac reflex
reflex bradycardia in respone to tension on extraocular muscles on pressure on eye
what happens in sympathetic reflex
wider
more light in
far objects
what happens in parasympatehtic reflex
less light in
nearer objects
reflex lacrimation
what happens when the eyes open wider
post synaptic sympathetic fibres travel via
- superior cervical sympahtetic ganglia
- internal carotid nerve
- internal carotid plexus
- axons carried on the ophtelamic artery
what does mitotic mean
constricted
eye symptoms of horners syndrome
mitotic
what does myadratic mean
enlarged
how are dilator pupillae aranged
radially
where do director pupillae attach to and from
originate around external circumference of iris (fixed)
insert around internal circumference of iris (mobile)
4 neurone chain of pupillary light reflex
retinal ganglion cells
pass via ipsilateral optic nerve
synapse in pretechtal nucleus
synapse in EW (location of cell bodies of parasympathetic axons of CN3)
pass from EW via CNS then its inferior division
synapse in ciliary ganglion
course in short ciliary nerves to sphincter papillae muscle
- reintal ganglion cells > pass via ipsilateral optic nerve > synapse in pretectal nucleus to next synapse in EW nucleus (location of cell bodies of parasympathetic axons of CN3)
- located entirely within midbrain + connect pretechtal nucleus to next synapse in EW nucleus (locataion of cell bodies of para axons of CN3)
- pass from EW nucleus via CN 3 then its inferior division, to synapse to ciliary ganglion
- course in short ciliary nerves to sphincted papillae muscles
basal tears
corneal health contain lysozone (hydrolyses bacteiral cell walls)
reflex tears
in response to mechanical or chemical sitmulation
afferent - CN V1 from cornea
efferent - parasympathetic axons from CN VII
treatmnet for bacterial conjunctivitis
chloramphenicol QTD
how not to treat herpetic keratitis
steroids - causes corneal melt
feature of herpetic keratis
dendritic ulcer
feature of adenoviral keratitis
subepithelial infiltrates
features of fungal keratitis
hypopyon
how to treat fungal keratiits
topical antifungal eg natamycin
what causes keratitis in contact lenses
acanthamoedema
what is oral cellulitis
direct extension from sinus
extension from orbital infection eg infection chalazion, dacrocystitis
what bug causes endophalamitits
staph epidermis
how to treat endophalamitis
intraviteal ameakin
inflam of intraocuar fluids
how to treat toxoplasmosis
clindamycin / azithryomycin + steroids
what can toxocara form
granulomas
how does chloramphenicol work
inhibits peptidyl transferase enzyme (therefore stops bacterial proteins being made)
when is chloramphenicol bacteriocidial
strep + haemophilus
when is chloramphenicol bacteriostatic
staph
side effects of chloramphenicol
allergy
irreversible aplastic anaemia
grey baby syndrome
which antibiotics inhibits the cell wall synthesis
penicillins + cephalosporins
beta lactam ring inhibits enzyme which make bacteriocidal cell wall (without cell wall, bacteria die)
which antibiotics inhibit nuclei acid synthesis
quinolones eg ofloaxin (inhibits DNA gyrase, an enzyme that compresses bacterial DNA into supercoils)
inhibition of DNA gyrase leads to unwinding of supercoils + cell death
how to treat bacterial keratitis
A-4 quinolone (ofloxacin) - treats gram neg
gentamicin and cefuromime (treats gram neg and positive
how to treat chlamydial conjunctiivits
oxytetracycline
via single median aparture and paired lateral appertures
pathway of CSF
ventircles > subarachnoid pace > absorped into venal circulation
when is the neural canal formed
at 3 weeks
which areas dont have a BBB
circumfrencicular organs + pineal glands
where are colloid cysts found
at interventricular foramen
where do ependymomas arise from
ependymal cells lining the ventricles
what is a epidermal haematoma
arterial bleed between the skull + dura
what is a subdural haematoma
venous bleed between dura + arachnoid
what is a hydrocelphaus
accumualtion of CSF
what does rhodopsin do when light hits
light converts 11-cis-retinal to all trans-retinal (activated form)
what is the dark current
opens in the dark
permeable to Na+
keeps photoreceptor Vm more positive than most neurons
steady release of neurotransmitter
which cells function in normal day light
cones
what does lysozome do
destroys bacterial cell wall
what are tear lipids antibacterial to
cell membranes
what does secretory IgA do
prevent attachment
what is the principle APC of the external eye
langerhans cell
what are langerhans cells rich in
MHC class 2
where are langerhan cells abundant
corneoslceral limbus
where are langerhan cells absent
from central 1/3rd of cornea
which part of the eye is the only part with lymphatic drainage
conjunctiva
what are the APC cells in the conjunctiva
dendritic cells
which area of the eye has MALT
conjunctiva
what unique function does the cornea and sclera have
down regulated the immune environment
what is ACAID
protects eyes + visual axis from collateral damage of an immune repsone to an ifnection by surpressing the response
do corneal cells have MHC class 2
no
primary mediators of sympathetic opthalamia
T cells
eg of immediate hypersensitivity (1)
acute allergic conjunctivitis
eg of direct cell killing (2)
ocular cicatricial pemphigoid
eg of immune complex mediated (3)
autoimmune corneal melting
eg of delayed (4)
corneal graft rejection
monro kellie hypothesis
maintain balance of brain, blood and CSF
what CN supplies dura matter
V
how to acess subarachnoid space
L3/L4 or L4/L5
when does subarachnoid space end
S2
what is glaucoma
increased pressure of eye dye to increase in humour - blockage of trabecular meshwork / canal of schlemm
what are primary open anled glaucoma
most common
poor drainage throuh trabecular meshwork
slow onset
what is closed angle glaucoma
patent drainage
1/3 emergency
visual loss
headaches
scleritis
rare
pain on movement
underlying autoimmune aetiology
genetics of scelritis
HLA B27
ARMD
accumulation of drusen
dry ARMD
no significant vascular proliferation
wet ARMD
vascualr proliferation
neovascularisation in choroid, mediated by VEGF
new vessels are small and leaky
what type of vision loss is seen in wet ARMD
rapid central visual loss
treatent of wet ARMD
monoclonal antibodies to VEGF
what kind of pupil is seen in diabetes
prostitie
argyll robertson
what causes cataracts
conversion of glucose to sorbiol in lens
is epithelium lipophilic or phobic
philic
is the stroma lipophilic or phobcic
phobic
does cholarmphenicol have lipophilic or phobic properties
both
when is prednisolone acetate used
post op
good penetration in uninflammed cornea
is prednisolone phosphate hypodrophic or philic
philic
what drug is used to lower IOP in glaucoma
0.03%
when are steroids used
post op cataracts
uveitis
to prvent corneal grat rejection
what is the glaucoma medication
prostaglandins eg latanoprost beta blockers carbonic anhydrase inhibitors alpha adrenergic agonists parasympathetic mimetics
what is fluroscein used for
to show corneal abraisons and dendritic ulcers
eg of myadratics and what they do
tropicamide + cyclopentolate
pupil dilation by blocking para block to MS
cause cytoplasgie (stops lens from foccusing)
what are sympathomimetics and give eg
act on sympa system to dilate pupil
optic neuropathy - ethambutol
maculopathy - chloroquine
what happens in diabetic retinopathy
glycosylation of protein / basement membrane > loss of pericytes > microaneurysms = leakage and ischaemia
what happens in hypertensive retinopathy
attenuated blood vessels cotton wool spots hard exudates retinal haemorrhages optic disc oedema
symptoms of corneal retinal arteyr occlusion
sudden painless loss of vision cherry red spot RAPD pale oedematous retina threadlike reintal vessels
what causes corneal retinal artery occlusion
carotid artery disease + emboli from heart
what causes cherry red spot in corneal retinal artery occlusion
retinal nerve fibre layer becomes swollen except at foeva
symptoms of central retinal vein occlusion
sudden painless visual loss associaated with diabetes, hypertension + cancer retinal haemorrhages dilated tortourous veins disc swelling + macular swelling
symptoms of branch vein occlusion
painless disutbance in visual field
sympotms of giant cell arteritis
middle sized arteritis headache jaw claudication malaise raised PV blinding condition
what is GCA associated with
polymyalgia rheumatic
signs of sjorgens
keratoconjunctivitis sicca
xerostomia
RA
infiltration of lacrimal glands
sympoms of RA eye disesase
keratoconjunctivitis sicca
sympyoms of SJ syndrome
symniblepharon
occlusion of lacrimal glands
corneal ulcers
3 types of retinal artery occlusion
branch
amarosis fugax (curtain coming down, 5 mins)
ION
what is ION (ischaemic optic neuropathy)
can be caused by temporal arteiits
posterior cilliary arteries affected (walls become so infamed that the lumen becomes occluded)
blood doesnt flow properly to optic nerve
sudden loss of vision
what cuases sudden vision loss in ION
occlusion of optic nerve head circulation
occlusion of posterior ciliary arteries
signs of vitreous haemorrhage
loss of vision
floaters
loss of red reflex
signs of retinal detachment
painless loss of vision
sudden onset floaters
signs of closed angle glaucoma
cupped disc (loss of retinal ganglion cells)
types of cataracts
nuclear
posterior subscapular cataract
christmas tree - polchroatic
congenital cataract
what happens in refractive error
eye cant focus myopia (short sighteD) hypermenopia (long sighted) astigmatism - irregular corneal curvature presbyopia - age related
painful 3rd nerve palsy
aneurysm
4th nerve palsy
congenital trauma
6th nerve palsy
cranial pressure
what is optic neuritis
progressive visual loss (unilateral )
pain behind eye on movement
occular desaturation
central scotoma - depressed vision at point of fixiation - suggests a lesion between optic nerve head and chiasm ( can be caused by MS)
