Eyelid and Third Eyelid Flashcards
4 layers of the eyelids
from outside to inside:
skin, muscle, tarsus and meibomian glands, conjunctiva
clinically relevant eyelid muscles
orbicularis oculi
levator palpbrae superioris
Muller’s muscle
dysfunction of the orbicularis oculi muscle will cause ________
lagophthalmos - incomplete eyelid closure and globe coverage
dysfunction of levator palpebrae superioris and muller’s muscle will cause ________
ptosis - drooping of the eyelids (most often upper eyelid)
what is the tarsus (tarsal plate)
fibrous and glandular layer of the eyelid
holding layer for eyelid closure, supports meibomian glands
T/F the palpebral conjunctiva is often slighly hyperemic relative to the bulbar conjunctiva
True
eyelid conformation and eyelid margin abnormalities
entropion
ectropion
lagopthalmos
abnormalities in innervation
abnormal hairs
eyelid tumors
entropion
rolling of the eyelid margin such that hairs are touching the ocular surface
key concept: this is an abnormal relationship of the eye in relation to the eyelids
anatomic entropion
eyelids not appropriately conformed to eye
unrelated to ocular pain
blepharospasm associated entropion
ocular pain stimulates active globe retraction and an altered eyelid to eye relationship
bleptharospasm
spasm of the orbicularis oculi muscle resulting in eyelid closure
aka squinting
hereditary causes of anatomic entropion
abnormal canthus - brachycephalic
abnormal palpebral fissue - hounds and giant breeds
escessive facial folds - shar pei
T/F permanent correction of hereditary anatomic entropion may not be necessary
True
dogs can “grow into their faces”; permanent correction may not be necessary until 6-9 months of age
causes aquired causes of anatomic entropion
enophthalmos
blepharospasm that alters anatomy - chronic corneal ulceration, dry eye, conjunctivits
Why do we care to differentiate anatomic and blepharospastic components?
Failure to assess the spastic component can lead to over correction and ectropion
how can we differentiate anatomic and blepharospasm entropion
take away the ocular pain that induces blepharospasm
proparacaine
temporary correction of entropion
viscous lubrication
eyelid tacking
partial temorary tarsorrhaphy
permanent correction of entropion
modified hotz-celsus - rolls out the eyelid
ectropion
eversion or rolling out of the eyelid
common causes of ectropion
iatrogenic - too agressive with entropion correction
hereidary - hounds and giant breeds (often in conjunction with entropion)
4 common causes of lagophthalmos (incomplete eyelid closure and globe coverage)
breed variation
exopthalmos
bupthalmos
CN V or CN VII dysfunction
secondary eye exposure from lagopthalmos will cause ______
keratoconjunctivitis
which nerves are afftected with an abnormal palpebral reflex
CN V (maxillary and opthalmic - sensory) and CN VII (somatic efferent)
which nerves are affected with ptosis
CN III or sympathetic pathway lesion (commonly a feature of Horner’s syndrome)
Clinical signs of Horner’s syndrome are due to disruption of which 3 target sites of the SNS
upper eyelid - muller’s muscle
iris - iris dilator
periorbital cone - circumferential smooth muscles
common causes of horners syndrome
otitis
nasopharyngeal polyps
iatrogenic
idiopathic
how can horners syndrome be diagnosed
dilute phenylephrine - post ganglionic horners should partially or completely resolve in <15 min
trichiasis
hairs growing from naormal skin reach the cornea and/or conjunctival surface
trichiasis commonly effects which breeds
brachycephalic
distichia
cilia which emerge from meibomian glands
which abnormal hair disorders are treated with cryotherapy
distichia
ectopic cilia
ectopic cilia
hair/cilia protruding through palpebral conjunctiva
T/F eyelid tumors in dogs are typcally malignant where as feline eyelid tumors are typically benign
False
canine tumors are typically benign and feline tumors are typically malignant
what should be considered with surgical removal of eyelid tumors
irritation of the ocular surface
size
location
treatment options for canine eyelid tumors
debulk and cryotherapy
complete excision
4 key concepts for closure of eyelid margin defects
limited debridement
closure must be perfect
avoid full thickness suture bites
tarsus is the holding layer
what suture pattern should be used to close eyelid margin defects
figure of 8
prolapsed gland of the third eyelid (cherry eye) can lead to ______ if left untreated
chronic conjunctivitis
KCS
T/F excisions of the gland is an appropriate therapy for cherry eye
False
contributes 35-45% of aqueous tear film, exception: third eyelid neoplasia
2 common techniques for treating cherry eye
morgan pocket technique
orbital tracking
