Final Exam - Eyelids & 3rd Eyelids Flashcards
what is an aphakic crescent?
crescent shaped lesion that verifies lens subluxation
what is buphthalamos?
globe enlargement secondary to glaucoma
what is band keratopathy?
corneal degeneration that forms in a a band shape roughly matching the shape of the palpebral fissure that is often associated with lagophthalmos but can occur independent of exposure
what is blepharospasm?
spasm of the orbicularis oculi muscle resulting in eyelid closure (squinting)
what are cilia?
eyelashes
what is trichiasis?
normal cilia that are directed toward the cornea
what are distichia?
eyelashes emerging from the meibomian glands
what are ectopic cilia?
cilia growing from the palpebral conjunctiva
what is ectropion?
outward rolling of the eyelids that make animals often develop exposure keratitis or conjunctivitis due to the poor ability of the eyelids to completely close over the ocular surface
what is the eyelid margin?
identified by the gray line of meibomian gland orifices that is important to identify when closing the eyelid surgically
what is entropion?
rolling in of the eyelid margin that results in hairs touching the ocular surface
what is exposure keratoconjunctivitis?
ocular surface inflammation secondary to chronic lagophthalmos - inflammation often aligns with the exposed region of the ocular surface in an ovoid or band pattern
what is lagophthalmos?
incomplete eyelid closure/coverage of the eyeball
what is the lateral canthus?
the lateral or temporal convergence of the upper & lower eyelids
what is lens-induced uveitis?
cataract formation reliably triggers intraocular inflammation & breakdown of the blood ocular barrier
what is the medial canthus?
medial or nasal convergence of the upper & lower eyelids
what is the palpebral fissure?
area outlined by the upper & lower eyelids
what is pigmentary keratitis?
most often described in brachycephalic breeds that refers to superficial corneal pigment dispersion following chronic exposure and/or irritation (often from medial canthus entropion)
what is primary glaucoma?
inherited form of glaucoma that most often involves abnormal anatomy & drainage at the iridocorneal angle
what is ptosis?
drooping of the eyelids (most evident by upper eyelid drooping) caused by sympathetic denervation to the eyelid
what is secondary glaucoma?
any form of glaucoma that doesn’t originate from a heritable disorder of the ICA that is most commonly associated with uveitis, hyphema, & neoplasia
T/F: lens luxation-associated glaucoma is sometimes categorized as ‘secondary’ although it relates to a primary inherited condition
TRUE
what is a tarsorrhapy?
surgical procedure in which the eyelids are sutured together
what is the tarsus?
fibrocartilaginous layer of the eyelid that contains the meibomian glands
what is the holding layer for surgical eyelid closures?
tarsus!!!
what is trichiasis?
hair growing from normal skin that reach the cornea/conjunctival surface - seen a lot with entropion, but we usually use this term when describing hairs from the nasal folds that are directed towards the eye in brachycephalic dogs
what are the 4 layers of the eyelid listed from superficial to deep?
- skin 2. muscle 3. tarsus & meibomian glands 4. conjunctiva
what is the clinical importance of the orbicularis oculi muscle? what nerve innervates it? what happens if it is damaged?
closes the eyelid like a zipper - CN VII (general somatic efferent) innervation - dyfsfunction will cause lagophthalmos
what is the clinical importance of the levator palpebrae superioris muscle? what nerve innervates it? what happens if it is damaged?
opens the upper eyelid - CN III (general somatic efferent) innervation - dysfunction will cause ptosis
what is the clinical importance of the muller’s muscle? what nerve innervates it? what happens if it is damaged?
opens the upper eyelid (general visceral efferent) innervation - dysfunction will cause ptosis
what is the key concept in understanding entropion? what must you do prior to treatment?
abnormal relationship of the eye in relation to the eyelids!!!!!! must identify the cause of the imbalance prior to treating
what is anatomic entropion?
eyelids aren’t appropriately conformed to the eye & its presence is unrelated to ocular pain, can be acquired or hereditary
what is blepharospasm-associated entropion?
ocular pain stimulates active globe retraction & an altered eyelid to eye relationship
why is it important to remember that dogs can grow into their face?
they may not need permanent correction until 6-9 months of age
what are some hereditary causes of entropion?
abnormal canthus - common in brachycephalics abnormal palpebral fissure - often too large/loose in hounds/giant breeds & excessive facial folds - sharpeis
what kind of anatomic entropion would you expect to see in a pug? what about a bloodhound?
pug - medial entropion bloodhound - lateral entropion because palpebral fissure is too large
what are some acquired causes of anatomic entropion?
enophthalmos & blepharospasm that alters anatomy (chronic corneal ulceration, dry eye, conjunctivitis as underlying causes)
why do we care to differentiate anatomic & blepharospastic components of entropion?
failure to assess the spastic component can lead to over correction & ectropion!!!
how can you differentiate between anatomic & blepharospastic entropion?
take away the ocular pain that causes blepharospasm!!! proparacaine - if it resolves, you know it’s blepharospasm
after identifying whether the entropion is anatomic or blepharospastic, what do you do?
determine if it is a temporary or permanent condition
what would you do for treating a dog with entropion from dehydration related enophthalmos?
don’t want permanent fix - no need to permanently alter the anatomy in an animal with a temporary problem
what are your options for temporarily treating entropion?
viscous lubrication - to provide a mild barrier to further irritation eyelid tacking - rolls out the eyelid & partial temporary tarsorrhapy - to bring the eyelid margins together
how do you permanently correct entropion?
modified hotz-celsus sutures - rolls out the eyelid
when may you use medical management for entropion? what does it include?
may use in mild cases which are most often small brachycephalic dogs with medial entropion & secondary pigmentary keratitis - optimmune!
what is an iatrogenic cause of ectropion?
too aggressive with entropion correction so that the eyelid everts/rolls out
ectropion is hereditary in what animals?
hounds & giant breeds - often in conjunction with entropion
does ectropion cause lagophthalmos?
it can but it requires treatment less often than entropion
what are the 4 common causes of lagophthalmos?
- breed variation (pugs) 2. exophthalmos 3. buphthalmos 4. CN V or VII dysfunction
what are the secondary concerns for animals with lagophthalmos?
secondary eye exposure will cause exposure keratoconjunctivitis and/or band keratopathy
what question should you ask an owner if you’re concerned that their pet has lagophthalmos?
ask if the dog sleeps with its eyes open - if yes & signs are present, then pursue treatment
what are your treatment options for lagophthalmos?
identify & treat underlying causes & provide eye protection via temporary correction (lubrication & temporary tarsorrhapy) or permanent correction (permanent partial tarsorrhapy, or cathoplasty)
what happens if keratitis is left untreated?
a degenerative band (band keratopathy) will form within the exposed region
what sensory nerve should be considered for eyelid innervation? what motor nerves should be considered?
sensory - CN V (maxillary & ophthalmic branches) motor - sympathetic to the upper eyelid to open it, CN III (somatic efferent) to open the eyelid, & CN VII (somatic efferent) to close the eyelid
if there are eyelid innervation abnormalitis, how can you detect them?
eith by the presence of ptosis or an abnormal palpebral reflex
T/F: CN III GSE lesions causing ptosis are less common that sympathetic GVE pathway lesions causing ptosis
TRUE
what are the 4 signs associated with horner’s syndrome?
set of ocular signs due to sympathetic denervation 1. miosis 2. enophthalmos 3. protrusion of the 3rd eyelid 4. ptosis
why do we see clinical signs with horner’s syndrome?
due to the disruption of 3 target sites of the sympathetic nerve upper eyelid - muller’s muscle, iris - iris dilator, & periorbital cone (circumferential smooth muscles) - allows for enophthalmos & secondary passive protrusion of the 3rd eyelid
what is the most common cause of horner’s syndrome? what are some other causes?
idiopathic post-ganglionic is most common!!!! otitis (post-ganglionic), nasopharyngeal polyps (post-ganglionic), & iatrogenic (venipuncture, feeding tubes, etc (pre or post-ganglionic)
how is horner’s syndrome diagnosed?
dilute phenylephrine (0.1%) - 1 drop to both eyesto utilize the concept of denervation hypersensitivity in which increased numbers of tissue adrenergic receptors develop at the site of denervation
when should post-ganglionic horner’s syndrome resolve?
should partially or completely resolve in under 15 minutes
what 3 conditions involving abnormal hairs can cause irritation to the cornea or conjunctiva?
- trichiasis 2. distichiasis 3. ectopic cilia
what treatment is indicated for trichiasis in brachycephalic breeds?
conservative - lubrication aggressive - facial fold resection
T/F: trichiasis can cause severe corneal disease in brachycephalic dogs
TRUE
what breeds are known to inherit distichia?
cockers, poodles, sheepdogs
when does distichia require treatment?
treatment required if causing corneal/conjunctival disease
how is cryotherapy used to treat distichia? what are the risks?
two freeze thaw cycles - freeze is applied to the palpebral conjunctiva & the ice ball advances just past the meibomian glands & then the hairs are plucked/epilated - multiple treatments are occasionally required - beware of eyelid necrosis & depigmentation
what animals are commonly affected by ectopic cilia? what clinical signs are seen?
common in brachycephalics, commonly causes severe pain & corneal disease that waxes & wanes due to the hair life cycle
how is cryotherapy used to treat ectopic cilia?
2 freeze thaw cycles - the freeze is applied to the palpebral conjunctiva & ice ball advances just past the meibomian glands & then the hairs are then sharply excised
what is the difference in biological behavior of eyelid tumors in dogs vs cats? how does this change your approach for treatment?
canine tumors most often demonstaret benign characteristics where feline eyelid tumors most often demonstaret malignant characteristics - for dogs, excise or debulk with biopsy only & in cats, consider incisional biopsy & tumor staging
what is the most common eyelid tumor in the dog?
meibomian gland adenoma
what 3 factors should be a part of your surgical considerations for a dog with an eyelid tumor?
- irritation to ocular surface? if so, remove or debulk 2. size: approaching 1/3 of the lid margin? can’t take more than 1/3 without causing functional disturbance, consider rotational graft/referral 3. location - involving nasolacrimal ducts or canthus?
what are the advantages & disadvantages of debulking & cryotherapy for canine eyelid tumors?
advantage - don’t need to reconstruct the lid margin disadvantage - higher chance of regrowth
what are the advantages & disadvantages of complete excision for canine eyelid tumors?
advantage - low chance of regrowth disadvantage - must reconstruct the lid margin & always submit for histopathology!!!
what are the 4 key concepts for closing eyelid margin defects?
- limited debridement 2. closure must be perfect - figure of 8 suture pattern at the margin 3. avoid the full thickness suture bites 4. the tarsus is the holding layer!!!!
what are the 2 surfaces of the 3rd eyelid?
palpebral surface lined with conjunctiva & bulbar surface lined with conjunctiva
what is the purpose of the 3rd eyelid cartilage?
gives the 3rd eyelid shape & structure (performs a squeegee like function) & supports the gland of the 3rd eyelid
what is the exception for excision of the 3rd eyelid?
3rd eyelid neoplasia!!! not acceptable for cherry eye!!!
what is the issue with a prolapsed 3rd eyelid?
it contributes to 35-45% of the aqueous tear film & if letft untreated, will cause chronic conjunctivitis & will likely cause KCS
what are the 2 most common techniques used for corrected a prolapsed 3rd eyelid?
- morgan pocket technique 2. orbital tacking
how is the morgan pocket technique done for correcting a prolapsed 3rd eyelid?
incise over the bulbar conjunctiva superior to & inferior to the gland without connecting the thin incision - suture continuously (knots are not visible because they are placed on the palpebral surface of the 3rd eyelid)
how is orbital tacking performed for correcting a prolapsed 3rd eyelid?
the 3rd eyelid is elevated & a cut is made over the orbital rim through the conjunctiva - suture is passed through the incision & engages periosteum with the needle directed through the palpebral surface & engages the gland of the 3rd eyelid at its base, apex, base, & then through the incision again - as the knot is secured, the suture anchors the 3rd eyelid gland in a ventral, more anatomic position
