OPHTHALMOLOGY Flashcards
what are the bones of the bony orbit
frontal maxilla zygomatic sphenoid lacrimal ethmoid
what is the base of the bony orbit called
the orbital rim
which bone makes up the majority of the roof of the bony orbit
frontal bone
what bone makes up the majority of the floor of the bony orbit
maxilla
what is the purpose of the orbital rim
protect the eye from direct trauma
what are the thinnest parts of the bony orbit
medial wall and orbital floor
what is a blowout fracture and its complications
medial wall/orbital floor fractured due to impact on the orbital rim
orbital contents can become trapped, damage to infraorbital NVB leading to general sensory deficit of facial skin
complication of fractured zygoma
diplopia
suspensory ligament of the eye attaches to the zygoma and droops in zygomatic fracture, causing one eye to lower
common cause of diplopia in young men
zygomatic fracture
the two parts of the orbicularis oculi
orbital part
palpebral part
what is the orbital septum and what is its function
a sheet of fascia deep to the ocularis oculi
prevents spread of infection from superficial to deep
where are the tarsal glands located and what is their purpose
embedded in tarsi
lipid secretion
what is the function of the conjunctiva
a defensive barrier to foreign bodies penetrating deep to it into the orbit
what I the conjunctival fornix
where the conjunctiva covering the eye meets the conjunctiva covering the lower eyelid
what is the limbus
corneoscleral junction
what is the function of the lacrimal gland
produces lacrimal fluid (tears)
innervation of the lacrimal gland
parasympathetic (CNVII)
where does lacrimal fluid drain out of the eye
lacrimal puncta to the nasolacrimal duct
what makes up the outer (fibrous) layer of the eye
sclera and cornea
what makes up the urea (vascular) layer of the eye
iris, ciliary body and choroid
what is the inner layer of the eye called
the retina
what is the anterior chamber of the eye
part of the anterior segment
between the cornea and iris
contains aqueous humour
what is the posterior chamber of the eye
part of the anterior segment
between the iris and suspensory ligaments
contains aqueous humour
what is the posterior segment of the eye
behind the eye
contain vitreous humour
where is aqueous humour produced in the eye
ciliary processes in the ciliary body
what is the purpose of aqueous humour
nourishes the anterior lens and cornea
where is aqueous humour reabsorbed
the scleral venous sinus (canal of scheme) at the iridocorneal angle
the ophthalmic artery is a branch of which main artery
internal carotid
what type of artery is the central artery of the retina
end artery
what are the main branches of the ophthalmic artery
nasal cavity branches
forehead (scalp) branches
what veins drain the orbit
posteriorly superior/inferior ophthalmic vein forehead (scalp) vein anteriorly facial vein
what is the danger triangle of the face
an area of the face which is drained by the facial nerve
this superficial venous system connects with the deep system draining the eye and is a possible route for infection to enter the brain
what are the four main parts of the retina
fundus
optic disc
macula
fovea
from anterior to posterior, what are the layers of the retina
axons of the ganglions cells
ganglion cells
photoreceptors
which axons cross at the optic chiasm
nasal axons
what are the extra ocular muscles
lateral, medial, superior and inferior rectus
inferior and superior oblique
levator palpeerde superioris
origin of the EO muscles
common tendinous ring
innervation of the EO muscles
LR6 SO4 AO3
which muscles work together to achieve pure elevation
superior rectus and inferior oblique
which muscles work together to achieve pure depression
superior oblique and inferior rectus
CNV1 supplies sensory innervation to
upper eyelid
cornea
conjunctiva
skin of the root/bridge/tip of nose
CNV2 supplies sensory innervation to
skin of the lower eyelid, over the maxilla, ala of nose, skin/mucosa of the upper lip
CNV3 supplies sensory innervation to
skin over temporomandibular joint apart from the angle of the mandible (C2,3)
which nerve passes through the supraorbital foramen
CNV1
which nerve passes through the infraorbital foramen
CNV2
sensory afferent limb of the blink (corneal) reflex
CNV1
motor (efferent) limb of blink (corneal) reflex
CNVII
where does CNIII connect to the CNS
between midline and pons
route of CNIII
leaves brain at junction between midline and pons
passes through superior orbital fissure
somatic motor to eye muscles
presynaptic parasympathetic axons to the ciliary ganglion
superior and inferior divisions
what types of nerves are long ciliary nerves
sympathetic
somatic sensory
what types of nerves are short ciliary nerves
sympathetic
parasympathetic
what type of ciliary nerve forms the first part of the blink reflex
long ciliary nerves
somatic sensory
eyes open wider
sympathetic/parasympathetic
sympathetic
pupils get wider
sympathetic/parasympathetic
sympathetic
pupils constrict
sympathetic/parasympathetic
parasympathetic
focus on near objects
sympathetic/parasympathetic
parasympathetic
reflex lacrimation
sympathetic/parasympathetic
parasympathetic
what type of muscle fibres does LPS contain
skeletal and smooth muscle
how do postsynaptic sympathetic fibres reach LPS
superior cervical sympathetic ganglion internal carotid nerve internal carotid plexus axons carried on the ophthalmic artery branches to LPS
what muscle is responsible for the sympathetic widening of the eyes
LPS
what type of nerves are responsible for dilating the pupil
sympathetics
action of mydriatic drugs
dilate the pupil
what muscles are responsible for dilating the pupil
dilator pupillae fibres
what type of nerve constrict the pupil
parasympathetics
what is a mitotic pupil
non-physiologically constricted
a mitotic pupil is a component of which syndrome
Horner’s syndrome
a fixed-dilated pupil as a sign of pathology to which nerve
CNIII
what muscle fibres are responsible for pupillary constriction
sphincter pupillae fibres
what is the afferent limb of the pupillary light reflex
CNII (ipsilateral)
what is the efferent limb of the pupillary light reflex
CNIII (bilateral)
pupillary light reflex only occurs in one eye
true/false
false
a consensual light reflex occurs in the contralateral eye
relaxation of the ciliary muscle is caused by which nerve type
relaxation of the ciliary body is caused by the absence of parasympathetic firing
relaxation of the ciliary muscle occurs in which type of vision
far vision
in far vision, what shape is the lens
flat
contraction of the ciliary muscle is caused by which type of nerve
parasympathetic
contraction of the ciliary muscle occurs in what type of vision
near vision
what shape is the lens in near vision
spherical
the accommodation reflex is in response to what type of vision
near
what are the three aspects of the accommodation reflex
pupillary constriction
bilateral convergence
bilateral relaxation of the lens (contraction of ciliary muscles)
what nerve is responsible for the accommodation reflex
CNIII
what enzyme do tears contain
lysozyme
afferent limb of reflex tears
CNVI
efferent limb of reflex lacrimation
CNVII (parasympathetic)
symptoms of Horner’s syndrome
miosis (constricted pupil)
ptosis (drooping eyelid)
reduced sweating
increased warmth and redness
what causes Horner’s syndrome
impaired sympathetic innervation to the head and neck
root of neck trauma, carotid dissection, internal jugular vein engorgement, deep cervical node mets, pancoast tumour
causative pathogens of bacterial conjunctivitis in neonates
staph aureus
neisseria gonorrhoeae
chlamydia trachomatis
causative pathogens of bacterial conjunctivitis in children/adults
staph aureus
strep pneumoniae
h influenzae (esp in children)
treatment of bacterial conjunctivitis
topical antibiotic
chloramphenicol
causative pathogens of viral conjunctivitis
adenovirus
herpes simplex
Herpes zoster
signs of chlamydial conjunctivitis
chronic history
unresponsive to treatments
bilateral involvement in young adults
may have symptoms of urethritis/vaginitis
causes of microbial keratitis
bacteria
viruses
fungi
what is a hypopyon
inflammatory cells in the anterior chamber of the eye
herpetic keratitis may be associated with
dendrites ulcer
why should steroids be avoided in herpetic keratitis
can cause corneal melt and perforation of the cornea
why would you give antibiotics in adenovirus keratitis
to prevent secondary infection
fungal causes of keratitis include
acanthomoeba
pseudomonas aeruginosa
signs orbital cellulitis
pain - esp on eye movements
often associated with paranasal sinusitis
pyrexia
erythema/oedema
what may a CT show in orbital cellulitis
orbital abscess
causative pathogens of orbital cellulitis
staph, strep, colifroms, H influenzae, anaerobes
signs of endophthalmitis
very painful
decreasing vision
very red eye
what is endopthalmitis
inflammation of the interior eye
most common cause of endophthalmitis
staph epidermis
pathogens associated with chorioretinitis
CMV in AIDS
toxoplasma gondii
toxocara canis (worm)
treatment of dendrites ulcers
antivirals (aciclovir)
treatment of chlamydial conjunctivitis
topical oxytetracycline
where is CSF produced
secretory epithelium of the choroid plexus
where is the choroid plexus found
in the ventricles of the brain
what is the function of CSF
mechanical protection (shock absorption) homeostatic function circulation (minor exchange of nutrients and waste products between blood and brain)
how is CSF analysed
lumbar puncture
normal appearance of CSF
colourless
which ventricles is choroid plexus found in
lateral, 3rd and 4th
what is the name of the foramen the connects the lateral ventricles to the 3rd ventricle
foramen of munroe
what is the name of the foramen that connects the 3rd ventricle to the 4th ventricle
aqueduct of sylvius
what are the names of the foramina that release CSF into the subarachnoid space
foramina of luschka (laterally)
foramen of megendie (median)
describe the circulation of CSF
lateral ventricles > foramen of Monroe > 3rd ventricle > aqueduct of sylvius > 4th ventricle > foramina of Luschka/foramen of magendie > subarachnoid space > arachnoid granulations > superior sagittal sinus
what does the BBB consist of
capillary endothelium
basal membrane
perivascular astrocytes
what is the function of the BBB
protect the brain from infection and toxins
what is hydrocephalus
accumulation of CSF in the ventricular system or around the brain leading to enlargement of one or more ventricles and increase in CSF pressure
cause of papilloedema
raised ICP transmitted to the subarachnoid space surrounding the optic nerve
visual symptoms of papilloedema
enlarged blind spot
blurring of vision
visual obscurations
loss of vision
what is the function of bicarbonate in the aqueous humour
buffers H+ produced in the cornea and lens by anaerobic glycolysis
what are the four main regions of a photoreceptor
outer segment
inner segment
cell body
synaptic terminal
type of photoreceptors
rods and cones
what is the name of the visual pigment molecule present in rods
rhodopsin
what happens to rhodopsin in the presence of light
it is converted to all-trans-retinal
what effect does all-trans-retinal have of cGMP
causes it to decrease
what is the effect of a decrease in cGMP
hyperpolarisation of the membrane
how does spacing of photoreceptors affect visual acuity
decreased spacing (closer together) increases VA
what are rods and cones used for
cones - colour
rods - dim light
how are rods and cones distributed
cones - central
rods - peripheral
what does high/low convergence mean
high convergence = more photoreceptors per ganglion cell
low convergence = fewer photoreceptors per ganglion cell
do rods/cones have high or low convergence
cones - low convergence
rods - high convergence
what effect does convergence have on vision
more convergence = increased sensitivity (low light), decreased acuity
how do we see colour
there are different opsin for different wavelengths (colours) of light
visual symptoms associated with raised ICP
transient blurred vision double vision loss of vision papilloedema pupillary changes
what are the three layers of the meninges
dura
arachnoid
pia
where is the sub-arachnoid space
between the arachnoid and Pia layers of the meninges
where does the dura mater get its nerve supply from
CNV
how does damage to CNIII manifest
paralysis of MR, IR, SR, IO paralysis of parasympathetic innervation of sphincter of pupil loss of pupillary light reflex ptosis eye turned inferolaterally
presentation of CNIV palsy
affected eye cannot move inferomedially
diplopia when looking down
presentation of CNVI palsy
medial deviation of the affected eye
assessment of eye trauma should include
history of the incident
visual acuities
examination of eye (lids, conjunctiva, cornea, anterior segment, pupils, fundus)
use of fluorescein drops
what do fluorescein drops identify
areas of epithelial loss
what is hyphaema
blood in the anterior chamber
what is commotion retinae
bruised retina
what is sympathetic ophthalmia
trauma to one eye resulting in auto-immune reaction in both eyes
may lead to bilateral blindness
signs of penetrating foreign body
irregular pupil
shallow anterior chamber
localised cataract
gross inflammation
investigation of intra-ocular foreign body
x-ray
treatment of chemical burns
irrigation with at least 2 L of saline
investigation
why does chloramphenicol easily penetrate the cornea
it is both lipophilic and hydrophilic
when is prednisolone acetate used
uninflamed cornea, post-operatively
when is prednisolone phosphate used
inflamed cornea, corneal disease
when low dose steroids are required (limited permeability in uninflamed cornea)
what is the function of benzalkonium
preservative that enhances corneal penetration and disrupts lipid layer of tear film
how to prevent systemic absorption of topical steroids
punctual occlusion
anti-inflammatory agents used in the eye
steroids NSAIDs
anti-histamines
mast cell stabilisers
indications for steroids
post op cataracts
uveitis
prevention of corneal graft rejection
temporal arteritis
local side effects of steroids
cataract
glaucoma
exacerbation of viral infection
drugs used to treat glaucoma
prostanoids beta blockers carbonic anhydrase inhibitors a2 adrenergic agonist parasympathomimetic
example of intravitreal drugs
anti-VEGF
antibiotics in endophthalmitis
IO steroids
how do mydriatic drugs work
block parasympathetic supply to iris
side effect of ethambutol
optic neuropathy
pathogenesis of diabetic retinopathy
chronic hyperglycaemia > glycosylation of protein/basement membrane > loss of perocytes > microaneurysms > leakage/ischaemia
signs of non-proliferative diabetic retinopathy
micro aneurysms (dot and blot haemorrhages)
hard exudate
cotton wool patches
abnormalities of venous calibre
intra-retinal microvascular abnormalities
new retinal vessel growth in a diabetic patient is a sign of
proliferative diabetic retinopathy
why do diabetic patients lose vision
retinal oedema affecting the fovea
vitreous haemorrhage
scarring/traction retinal detachment
management of diabetic retinopathy
laser (PRP/macular grid)
vitrectomy
features of hypertensive retinopathy
attenuated blood vessels - copper or silver wiring cotton wool spots hard exudates retinal haemorrhage optic disc oedema
cherry red spot is a sign of
central retinal artery occlusion
presentation of central retinal artery occlusion
sudden painless, profound loss of vision
presentation of central vein occlusion
sudden painless visual loss, range of visual loss
patient presents with headache, jaw claudication, malaise, raised PV and loss of vision
GCA (temporal arteritis)
extra ocular signs of thyroid eye disease
proptosis
lid retraction/lag/oedema/pigmentation
restrictive myopathy
ocular signs of thyroid eye disease
chemosis injection glaucoma choroidal folds optic nerve swelling
RA eye signs
dry eyes
scleritis
corneal melt
sjorgen’s eye signs
dry eyes
Marfan’s eye signs
conjunctivitis
retinal detachment
stevens-johnson syndrome
symplepharon
corneal ulcers
causes of sudden visual loss
vascular aetiology vitreous haemorrhage retinal detachment ARMD wet type closed angle glaucoma
vascular causes of sudden visual loss
occlusion of retinal circulation (artery/vein)
occlusion of optic nerve head circulation
haemorrhage from abnormal vessels (diabetes, wet ARMD)
retinal tear
signs of CRAO
relative afferent pupil defect
pale, oedematous retina, thread-like vessels
causes of CRAO
carotid artery disease
emboli from the heart (unusual)
management of CRAO
ocular massage id early presentation
establish source of embolus
assess and manage risk factors
variants of CRAO
branch retinal artery occlusion
amaurosis fugax
what is amaurosis fugax
transient CRAO
symptoms of amaurosis fugax
transient painless visual loss
‘like a curtain coming down’
lasts <5 mins with full recovery
treatment of amaurosis fugax
aspirin
causes of CRVO
atherosclerosis
hypertension
hyperviscosity
raised IOP
signs of CRVO
retinal haemorrhages
dilated tortuous veins
disc and macular swelling
treatment of CRVO
laser treatment of new vessels
anti-VEGF
address risk factors
occlusion of optic nerve head circulation is also known as
ischaemic optic neuropathy
which arteries become occluded in ischaemic optic neuritis
posterior ciliary arteries
presentation of ischaemic optic neuropathy
sudden profound visual loss
what are the two types of ischaemic optic neuropathy
arteritic (GCA)
non-arteritic (athersclerotic)
arteritic ischaemic optic neuritis causes reversible blindness
true/false
false
vision loss associated with GCA is irreversible
treatment of GCA
high dose steroids
signs and symptoms of vitreous haemorrhage
loss of vision
floaters
loss of red reflex
may see haemorrhage on fundoscopy
management of vitreous cause
management of cause
vitrectomy if not resolving
signs and symptoms of retinal detachment
painless loss of vision
sudden onset flashes/floaters
may have RAPD
may see tear on ophthalmoscopy
management of retinal detachment
surgical
2 types of ARMD
wet
dry
pathogenesis of wet ARMD
new blood vessels grow under the retina
leakage causes build up of fluid/blood and eventually scarring
signs and symptoms of wet ARMD
rapid central visual loss
distorsion (metamorphopsia)
haemorrhage and exudate
treatment of wet ARMD
anti-VEGF
symptoms of closed angle glaucoma
painful, red eye
visual loss
nausea and vomiting
headache
treatment of closed angle glaucoma
medication to lower IOP
laser iridotomy
causes of gradual visual loss
cataract ARMD dry type refractive error glaucoma diabetic retinopathy
symptoms of cataract
gradual decline in vision (hazy/blurred) that cannot be corrected with glasses
may get glare
management of cataract
surgical removal with intra-ocular lens implant
signs of symptoms of dry ARMD
gradual decline in vision
central vision missing (scotoma)
drusen (build up of waste products below RPE)
atrophic patches of retina
myopia
shortsighted
hypermetropia
longsighted
astigmatism
irregular corneal curvature
presbyopia
loss of accommodation with ageing
in myopia, light diverges before/after the retina
before
in hypermetropia light diverges before/after the retina
after
pathogenesis of open angel glaucoma
resistance to outflow of aqueous humour in trabecular network leading to build up of aqueous humour and raised IOP
symptoms of glaucoma
often asymptomatic
may have visual loss
signs of glaucoma
cupped disc
visual field defect
may/may not have high IOP
papilloedema vs swollen optic disc
swollen optic disc = swelling due to any cause
papilloedema = swollen disc due to raised ICP
bilateral optic disc swelling and suspected ICP may be due to
a space occupying lesion
CNII examination includes
ophthalmoscopy VA pupil exam visual field assessment colour vision
what is blepharitis
inflamed eyelids
what causes posterior blepharitis
meibomian gland disease
treatment of blepharitis
lid hygiene
tear drops
oral doxy 2-3 months
non-infective causes of conjunctivitis
allergic
chemical/drugs
skin disease) eczema
signs of conjunctivitis
red eye discharge papillae or follicles sub conjunctival haemorrhage chemosis (oedema) pre-auricular glands (if viral)
papillae are associated with which type of conjunctivitis
bacterial
follicles are associated with which types of conjunctivitis
viral
chlamydial
drugs
keratitis affect which part of the eye
cornea
what are the three layers of the cornea
epithelium
strome
endothelium
symptoms of corneal ulcers
pain photophobia profuse lacrimation vision may be reduced red eye (around cornea)
treatment of scleritis
oral NSAIDs
oral steroids
steroid sparing agents
