Opthamology Flashcards
painless causes of loss of vision
central retinal vein or artery occlusion
retinal detachment
vitreous haemorrhage
ischaemic optic neuropathy
what is ischaemic optic neuropathy caused by
arteritis eg temporal arteritis or atherosclerosis eg hypertensive, diabetic may be older patient
what is ischaemic optic neuropathy caused by
occlusion of the short posterior ciliary artery, causing damage to the optic nerve
retinitis pigmentosa
night blindness and tunnel vision
horners syndrome features
ptosis
anhydrosis
miosis (small pupil)
enopthalmos
how does the pupil differ in a third nerve palsy from horners syndrome
in horners syndrome the pupil is constricted miosis but in CNIII palsy there is pupil dilatation as CNIII cannot cause constriction so have dilated pupil and mydriasis
what conditions can make glaucoma more likely to come on
WHEN THE PUPIL IS DILATED
this could be while watching television or in dim light when the light from the screen flares
what are the risk factors for macular degeneration
age, smoking, family history, Caucasians, high sunlight, female
what is the normal range of intraocular pressure
10-21mmHg
Blepharitis is more common in those with which condition
rosacea
what is more common anterior or posterior blepharitis
posterior due to meiobionan gland dysfunction
treatement of blepharitis
softening of lid margin using hot compresses 2 times a day
mechanical removal of the debris from the lid margins
what symptoms does blepharitis cause
dry eyes, red eyes, red eyelid margin, symptoms usually bilateral, grittiness and discomfort
why are the eyes dry in blepharitis
meibomian glands secrete oil on to the surface of the eye to prevent rapid evaporation of the tear film, any problem affecting meibomian glands can hence dry the eyes leading to irritation
why does hutchinsons sign a strong risk factor for ocular involvement
it indicates nasociliary involvement
what do follicles suggest
viral
what do papillae suggest
bacterial
what is episcleritis associated with
gout
infective ulcers tned to be found where in the cornea
central
autoimmune ulcers tend to be found where in the cornea
in the periphery
what are the most common organisms in acute bacterial conjuncitivits
staph aureus, strep pneumonia, h, influenzae
what is the dura mater
tough outer protective layer
what is the sensory supply to the dura mater
CN V
what is enclosed by the dura mater
the dural venous sinuses
what is in the arachnoid mater
arachnoid granulations
what is the subarachnoid space
circulating CSF and blood vessels
pia mater function
adheres to brain (and vessels and nerves entering or leaving)
where is the subarachnoid space
between the arachnoid and pia mater
what is the nerve supply to the dura mater
CN V
where does the subarachnoid space close/end
S2
where is the third ventricle located
in the midline within the diencephalon
where is the 4th ventricle located
between the cerebellum and the pons
what happens when the trochlear nerve is damaged
inferior oblique is unopposed eye cannot move inferomedially
diplopia when looking down
how is abducent nerve susceptible to damage
from stretching
where does the ophthalmic artery travel through
the optic canal
what type of fibres are contained in the long ciliary nerve
sympathetic and somatic sensory
what does the long ciliary nerve form part of
the afferent limb of the blink (corneal) reflex
what do the ciliary nerves supply
autonomic axons to control the diameter of the iris and pupil and the refractive shape of the lens
what do the long ciliary nerves form part of
the first part of the afferent limb of the blink(corneal) reflex)
what is contained in the short ciliary nerve
sympathetic, parasympathetic and somatic sensory
what kind of diplopia would damage to the suspensory ligament cause
vertical diplopia
what does a fracture in the zygoma/maxilla potentially cause
damage to the infraorbital branch of V2 resulting in a potentially large area of altered sensation of the lower eyelid, skin over maxilla, ala of external nose and upper lip
what is the infraorbital nerve a branch of
V2
what is the angle of the mandible supplied by
C2,3 spinal nerves
what is the sensory supply to the ear lobe
C2,3
what is the sensory supply to the tragus
V3
what supplies most of the tympanic membrane externally
CN V3
what supplies the inferior part of the tympanic membrane
CNX
what is the sensory supply to the Eustachian tube
CN IX
what drains into the superior meatus
posterior ethmoidal cells
what is the oculocardiac reflex and what nerves are involved
reflex bradycardia in response to tension on the extraocular muscles or pressure on the eye CNS connections between CNV1 or CNX
what nerves are involved in coordinating the vestibulocular reflex
CNIII, IV, VI and VIII, 3,4,6,8
what type of muscels is in the levator palpebrae superiooris
skeletal and smooth muscle
how do sympathetic fibres reach the levator palpebrae superioris
superior cervical sympathetic ganglion, internal carotid nerve, internal carotid plexus, axons carried on the ophthalmic artery and on its branches to the orbital structures
what causes the pupil to dialte
sympathetics, in dim light and fight or flight or non physiologically with mydriatic pupil
where is the insertion of the dilator pupillae fibres
around the internal circumference of the iris
where is the origin of the radially arranged dilator pupillae fibres
all around the external circumference of the iris
what is a pinpoint pupil
a fixed pupil with no response to light
what do parasympathetics do to the pupil
cause pupil constriction
what is a non physiologically constricted pupil
miotic pupil
what is a miotic pupil a component of
horners syndrome
what is a fixed dilated (blown( pupil a sign of
a serios pathological sign eg of CNIII pathology
as it is inhibiting the pupillary constricting action of parasympathetic axons in the ciliary nerve
where are the sphincter pupillae fibres
an encircling arrangement of the sphincter pupillae fibres all around the internal circumference of the iris
where is the pretectal nucleus
in the midbrain
where are the cell bodies of the parasympathetic axons located
in the edinger westphal nucleus
explain the pupillary light reflex
the first neurones pass via the retinal ganglion cells to cross in the optic chiasm to the pretectal nucleus in the midbrain
then synapse with edinger westphal nucleus where the cell bodies of the parasympathetic axons are located and then pass from EW nucleus VIA CNIII then its INFERIOR DIVISION to synapse in the ciliary ganglion, then course in the short ciliary nerve to the sphincter pupillae muscles
explain the shape of the lens in far away vision
the ciliary muscle is RELAXED in far vision
ligament TIGHTENS
lens FLATTENS to focus on distant objects
why does the lens become spherical
due to contraction of the ciliary muscles (CN III)
what can lysozyme do
an enzyme that can hydrolyse bacterial cell walls
what is the afferent limb for the formation of reflex tears
CN VI
what type of cartilage is in the ear
elastic cartilage
what 3 parts does the accommodation reflex test
bilateral pupillary constriction in response to CNS III
bilateral convergence-medial rotation of both eyes
bilateral relaxation of the lens-lens become spherical due to contraction of the ciliary muscles
what way do you pull the ear canal in adults
posteriosuperiorly
what is the angle in glaucoma
iridiocorneal angle
what do the tarsal glands secrete
lipid
which bone are the optic canal and the superior orbital fissure located in
the sphenoid bone
where is CN II formed
at the optic disc
what is at greatest density at the macula
cones
what is the fovea
centre of the macula, depression 1.5mm diameter, area of most acute vision
what causes the damage in giant cell arteritis to vision
anterior ischaemic optic neuropathy
what are the symptoms of dacrocystitis
inflammation of the lacrimal sac
swelling and erythema at the inner canthus of the eye
what is the canthus of the eye
either corner of the eye where the upper and lower eyelids meet
what is dacrocysitits
inflammation of the lacrimal sac
how is dacrocystitis treated
systemic antibiotics, IV antibiotics are indicated if there is associated periorbital cellultis
at what age is a childs visual acuity the same as that of an adult
2 years
what is a feature of keratitis
corneal ulcers
