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