Diseases of Adnexa and Cornea

Question 1

which nerve provides SENSORY innervation the eyelid?

Answer 1

trigeminal

Question 2

which nerve(s) provide(s) MOTOR to the eyelid?

Answer 2

facial and some input from the oculomotor

Question 3

which ocular muscle facilitates CLOSURE of the eye?

Answer 3

orbicularis oculi

Question 4

which ocular muscle facilitates OPENING of the eye?

Answer 4

levator palpebrae superioris

Question 5

What are the 4 functions of the eyelid?

Answer 5

1. direct protection of the eye (blinking)
2. entrapment and removal of material
3. distribution of tears
4. production of glandular secretions (meibomian glands) contributing to tear film

Question 6

_________ is a T-shaped cartilage in the eye with its own gland.

Answer 6

nictitating membrane (third eyelid)

Question 7

T/F: movement of the 3rd eyelid is direct

Answer 7

false – it is indirect meaning there are no muscles controlling the movement.

Question 8

______ is the conjunctiva lining the eyelids

Answer 8

palpebral conjunctiva

Question 9

________ is the conjunctiva covering the globe

Answer 9

bulbar conjunctiva

Question 10

________ is the junction of the conjunctiva that covers the 3rd eyelid and palpebral conjunctiva.

Answer 10

fornix of the 3rd eyelid.

Question 11

which eyelid does entropion most commonly involve in horses?

Answer 11

lower eyelid

Question 12

__________ is one of the most common congenital ocular abnormalities in foals and is typically resulting from concurrent underlying disease (dehydration, neonatal maladjustment syndrome, etc.)

Answer 12

entropion (inversion of the eyelid margin)

Question 13

what are clinical signs of entropion?

Answer 13

• epiphora
• blepharospasm
• conjunctivitis
• keratitis
• corneal ulcer

(becomes self-perpetuating)

Question 14

how do you treat entropion in foals?

Answer 14

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.

Question 15

Though permanent correction of entropion is rarely required in horses, what would be the procedure to perform?

Answer 15

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.

Question 16

What are the 3 causes of eyelid lacerations in horses and how can you differentiate them?

Answer 16

1. blunt trauma – irregular laceration with lots of swelling; usually NOT full thickness
2. direct contact with a sharp object – focal, straight laceration
3. ripping of the eyelid – usually occurs in upper lid.

Question 17

how do you treat eyelid lacerations in horses?

Answer 17

1. sedate horse (standing or gen anesthesia)
2. place local block
3. clean wound with saline or dilute betadine
4. perform very minimal debridement (do not excise tissue just freshen edges ensuring to preserve the eyelid margin)
5. perform primary, 2-layer closure to align eyelid margin (tarsoconjunctival layer with absorbable, musculocutaneous layer with nonabsorbable) with the figure 8 pattern

Question 18

What 2 things would you provide a horse as post-operative care after an eyelid laceration repair?

Answer 18

1. protective mask
2. TAB ointment (for 1-2 wks)

rarely may add: systemic NSAIDs (banamine) and systemic antibiotics (if you were concerned about an established infection)

Question 19

What would be the result of your suture going full thickness in the tarsoconjunctival layer during an eyelid laceration repair?

Answer 19

suture will rub on the cornea and create a corneal ulcer

Question 20

What would be the result of accidentally removing too much eyelid margin during an eyelid laceration repair?

Answer 20

poor tear film retention and/or distribution leading to chronic keratitis

Question 21

What are clinical signs of facial paresis/paralysis?

Answer 21

• ptosis/unable to blink
• ear droop/unable to move it
• nose deviation
• flaccid lip/unable to use

Question 22

what are the 3 possible causes of facial paresis/paralysis in horses?

Answer 22

1. trauma
2. inflammation of inner ear, guttural pouch, salivary gland
3. fracture of the stylohyoid, petrous temporal bone, or ramus of mandible

Question 23

How would you treat a case of facial paresis/paralysis regarding the CORNEA?

Answer 23

1. apply topical lubricant 4-6x/day
2. topical management of a corneal ulcer if its present
3. may perform partial temporary tarsorrhaphy
4. manage any underlying condition (traumatic, inflammatory, etc.)

Question 24

T/F: most traumatic cases of facial paresis/paralysis resolve within 3-4 weeks

Answer 24

true

after that, prognosis declines. if non-resolving, you should consider a permanent partial eyelid closure.

Question 25

What are clinical signs of conjunctivitis?

Answer 25

- hyperemia - chemosis - ocular discharge

Question 26

T/F: primary conjunctivitis is the most common form of conjunctivitis

Answer 26

false -- primary is rare (eosinophilic, allergic, bacterial, fungal, viral, parasitic, solar). Conjunctivitis is usually a secondary issue from ulcers, uveitis, etc.

Question 27

how do we diagnose and treat a horse with conjunctivitis?

Answer 27

we can diagnose it by cytology +/- culture but the treatment is going to depend on the underlying cause (ulcer vs keratitis vs something else)

Question 28

What is the MOST common neoplasm of horses?

Answer 28

Sarcoid

Question 29

What 3 horse breeds are at increased risk for sarcoids?

Answer 29

QH, appaloosas, and arabians

Question 30

T/F: metastasis of sarcoids is rare

Answer 30

true recurrence, however, is very common

Question 31

T/F: you must biopsy a sarcoid in order to make a definitive diagnosis

Answer 31

false -- do not biopsy these things because it makes it angry. just diagnose by identification and then choose an aggressive treatment.

Question 32

how would you treat an equine sarcoid?

Answer 32

AGGRESSIVELY! surgical excision WITH adjunctive cryo, hyperthermia, radiation, chemo, or immunotherapy. Note: surgical excision alone carries a very high rate of angry recurrence.

Question 33

what is the MOST common neoplasm of the equine eye and ocular adnexa?

Answer 33

squamous cell carcinoma note: and it is the second most common tumor overall

Question 34

which location of ocular SCC carries the BEST prognosis? A. 3rd eyelid and medial canthus B. limbus C. eyelid

Answer 34

A. 3rd eyelid and medial canthus

Question 35

which location of ocular SCC carries the WORST prognosis? A. 3rd eyelid and medial canthus B. limbus C. eyelid

Answer 35

C. eyelid

Question 36

T/F: SCC is locally invasive and quickly metastasizes

Answer 36

false -- it is locally invasive, but slow to metastasize it will met to local lymph nodes, salivary glands, olfactory region, and the lungs.

Question 37

T/F: color dilute horses have a predilection to SCC

Answer 37

true

Question 38

what is carcinoma in situ?

Answer 38

cancerous cells that have not gone through the basement membrane

Question 39

What is the best treatment approach for SCC?

Answer 39

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.

Question 40

What is the most common congenital nasolacrimal abnormality in foals?

Answer 40

imperforate nasal punctum

Question 41

what results from an imperforate nasal punctum?

Answer 41

severe epiphora and the discharge usually becomes mucopurulent due to secondary bacterial overgrowth (dacryocysistitis)

Question 42

what is the best way to diagnose imperforate nasal punctum or nasoilacrimal duct atresia?

Answer 42

visually observe a lack of nasal punctum OR an inability to flush the NL duct.

Question 43

how do you treat imperforate nasal puncta?

Answer 43

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.

Question 44

T/F: acquired nasolacrimal obstruction and dacryocystitis is an uncommon disorder.

Answer 44

true it can be diagnosed by jones test, flushing the NL duct, and culturing. Treatment is flushing and topical antibiotics.