Diseases of Adnexa and Cornea Flashcards
which nerve provides SENSORY innervation the eyelid?
trigeminal
which nerve(s) provide(s) MOTOR to the eyelid?
facial and some input from the oculomotor
which ocular muscle facilitates CLOSURE of the eye?
orbicularis oculi
which ocular muscle facilitates OPENING of the eye?
levator palpebrae superioris
What are the 4 functions of the eyelid?
- direct protection of the eye (blinking)
- entrapment and removal of material
- distribution of tears
- production of glandular secretions (meibomian glands) contributing to tear film
_________ is a T-shaped cartilage in the eye with its own gland.
nictitating membrane (third eyelid)
T/F: movement of the 3rd eyelid is direct
false – it is indirect meaning there are no muscles controlling the movement.
______ is the conjunctiva lining the eyelids
palpebral conjunctiva
________ is the conjunctiva covering the globe
bulbar conjunctiva
________ is the junction of the conjunctiva that covers the 3rd eyelid and palpebral conjunctiva.
fornix of the 3rd eyelid.
which eyelid does entropion most commonly involve in horses?
lower eyelid
__________ is one of the most common congenital ocular abnormalities in foals and is typically resulting from concurrent underlying disease (dehydration, neonatal maladjustment syndrome, etc.)
entropion (inversion of the eyelid margin)
what are clinical signs of entropion?
- epiphora
- blepharospasm
- conjunctivitis
- keratitis
- corneal ulcer
(becomes self-perpetuating)
how do you treat entropion in foals?
temporary eyelid tacking with vertical mattress suture (4 to 6-0) non-absorbable monofilament suture.
roll eyelid margin away from corneal contact and leave sutures for 2-3 wks.
Though permanent correction of entropion is rarely required in horses, what would be the procedure to perform?
Hotz-Celsus
make an incision 2-2.5mm from and parallel to the eyelid margin, extend it medial and lateral. then make a second incision and excise the skin and underlying orbicularis muscle.
use a simple interrupted skin closure.
What are the 3 causes of eyelid lacerations in horses and how can you differentiate them?
- blunt trauma – irregular laceration with lots of swelling; usually NOT full thickness
- direct contact with a sharp object – focal, straight laceration
- ripping of the eyelid – usually occurs in upper lid.
how do you treat eyelid lacerations in horses?
- sedate horse (standing or gen anesthesia)
- place local block
- clean wound with saline or dilute betadine
- perform very minimal debridement (do not excise tissue just freshen edges ensuring to preserve the eyelid margin)
- perform primary, 2-layer closure to align eyelid margin (tarsoconjunctival layer with absorbable, musculocutaneous layer with nonabsorbable) with the figure 8 pattern
What 2 things would you provide a horse as post-operative care after an eyelid laceration repair?
- protective mask
- TAB ointment (for 1-2 wks)
rarely may add: systemic NSAIDs (banamine) and systemic antibiotics (if you were concerned about an established infection)
What would be the result of your suture going full thickness in the tarsoconjunctival layer during an eyelid laceration repair?
suture will rub on the cornea and create a corneal ulcer
What would be the result of accidentally removing too much eyelid margin during an eyelid laceration repair?
poor tear film retention and/or distribution leading to chronic keratitis
What are clinical signs of facial paresis/paralysis?
- ptosis/unable to blink
- ear droop/unable to move it
- nose deviation
- flaccid lip/unable to use
what are the 3 possible causes of facial paresis/paralysis in horses?
- trauma
- inflammation of inner ear, guttural pouch, salivary gland
- fracture of the stylohyoid, petrous temporal bone, or ramus of mandible
How would you treat a case of facial paresis/paralysis regarding the CORNEA?
- apply topical lubricant 4-6x/day
- topical management of a corneal ulcer if its present
- may perform partial temporary tarsorrhaphy
- manage any underlying condition (traumatic, inflammatory, etc.)
T/F: most traumatic cases of facial paresis/paralysis resolve within 3-4 weeks
true
after that, prognosis declines. if non-resolving, you should consider a permanent partial eyelid closure.
What are clinical signs of conjunctivitis?
- hyperemia
- chemosis
- ocular discharge
T/F: primary conjunctivitis is the most common form of conjunctivitis
false – primary is rare (eosinophilic, allergic, bacterial, fungal, viral, parasitic, solar).
Conjunctivitis is usually a secondary issue from ulcers, uveitis, etc.
how do we diagnose and treat a horse with conjunctivitis?
we can diagnose it by cytology +/- culture
but the treatment is going to depend on the underlying cause (ulcer vs keratitis vs something else)
What is the MOST common neoplasm of horses?
Sarcoid
What 3 horse breeds are at increased risk for sarcoids?
QH, appaloosas, and arabians
T/F: metastasis of sarcoids is rare
true
recurrence, however, is very common
T/F: you must biopsy a sarcoid in order to make a definitive diagnosis
false – do not biopsy these things because it makes it angry. just diagnose by identification and then choose an aggressive treatment.
how would you treat an equine sarcoid?
AGGRESSIVELY!
surgical excision WITH adjunctive cryo, hyperthermia, radiation, chemo, or immunotherapy.
Note: surgical excision alone carries a very high rate of angry recurrence.
what is the MOST common neoplasm of the equine eye and ocular adnexa?
squamous cell carcinoma
note: and it is the second most common tumor overall
which location of ocular SCC carries the BEST prognosis?
A. 3rd eyelid and medial canthus
B. limbus
C. eyelid
A. 3rd eyelid and medial canthus
which location of ocular SCC carries the WORST prognosis?
A. 3rd eyelid and medial canthus
B. limbus
C. eyelid
C. eyelid
T/F: SCC is locally invasive and quickly metastasizes
false – it is locally invasive, but slow to metastasize
it will met to local lymph nodes, salivary glands, olfactory region, and the lungs.
T/F: color dilute horses have a predilection to SCC
true
what is carcinoma in situ?
cancerous cells that have not gone through the basement membrane
What is the best treatment approach for SCC?
surgical excision PLUS adjunctives (cryo, radiation, hyperthermia, immunotherapy, chemo, or photodynamic therapy)
can also consider enucleation, exenteration, and euthanasia.
surgical excision alone carries a 50-60% recurrence rate.
What is the most common congenital nasolacrimal abnormality in foals?
imperforate nasal punctum
what results from an imperforate nasal punctum?
severe epiphora and the discharge usually becomes mucopurulent due to secondary bacterial overgrowth (dacryocysistitis)
what is the best way to diagnose imperforate nasal punctum or nasoilacrimal duct atresia?
visually observe a lack of nasal punctum OR an inability to flush the NL duct.
how do you treat imperforate nasal puncta?
create a nasal punctum by passing a catheter and cutting an opening.
leave the catheter in for 4-6 weeks so that it will heal and prevent re-obstruction.
treat any secondary infections present.
T/F: acquired nasolacrimal obstruction and dacryocystitis is an uncommon disorder.
true
it can be diagnosed by jones test, flushing the NL duct, and culturing.
Treatment is flushing and topical antibiotics.
