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LA dx/tx > Conjunctiva, Cornea > Flashcards

Conjunctiva, Cornea Flashcards

1
Q

What block will help you with opening the eyelid of a horse?

A

Auriculopalpebral nerve block

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2
Q

What nerve block will give you anesthesia of the upper eyelid?

A

Frontal nerve block (branch of trigeminal) in the supraorbital foramen

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3
Q

What are the three common uses of a fluorescein stain?

A

Diagnosis and characterization of corneal ulceration
Demonstration of nasolacrimal patency
Demonstration of corneal perforation

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4
Q

What are the 5 layers of the cornea?

A

Pre corneal tear film
Corneal epithelium
Corneal stroma
Descemete’s membrane
Endothelium

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5
Q

What is the most sensitive structure in the mammalian body?

A

Cornea

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6
Q

What are dermoids?

A

Non progressive congenital lesions consisting of epithelial and dermis like components found in an abnormal location

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7
Q

Where do dermoids most frequently arise from?

A

Limbus

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8
Q

What is curative for dermoids?

A

Complete surgical excision

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9
Q

What breeds are megalocornea and cornea globosa (MCOA) seen in?

A

Rocky mountain horses
Coat color association - chocolate coats with white mane and tail

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10
Q

What do horses with megalocornea and cornea globosa have an increased risk for?

A

Corneal ulceration and exposure keratitis

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11
Q

What is eosinophilic keratoconjunctivitis?

A

Inflammatory disease of the cornea and conjunctiva
White raised plaques on the cornea and/or conjunctiva
Most cases are within the summer months

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12
Q

How would you diagnose eosinophilic keratoconjunctivitis?

A

Eosinophils on corneal cytology

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13
Q

How would you treat eosinophilic keratoconjunctivitis?

A

Oral steroids (dexamethasone)
Oral antihistamine (cetirizine)
Topical antibiotic - only if corneal ulceration is present

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14
Q

When would you do a follow up for eosinophilic keratoconjunctivitis? What is the average healing time?

A

Initial recheck in ~2 weeks, serial follow up monthly until resolved
Takes about 2.5 months to heal
1/3 recurrence rate

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15
Q

What is KCS most commonly associated with in horses?

A

Loss of parasympathetic nerve supply to lacrimal tissue (facial nerve)
Associated with trauma, mandibular fracture, stylohyoid fracture

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16
Q

How would you treat KCS supportively?

A

Topical tear stimulant (Tacrolimus or cyclosporine)
Topical tear replacement
Topical antibiotic if corneal ulcer

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17
Q

What is a simple corneal ulcer?

A

Superficial with no signs of infection or stromal loss

18
Q

How would you treat a simple corneal ulcer?

A

Topical antibiotic q 8 hr
Topical atropine sulfate 1% given once in clinic
Systemic NSAID q 12-24 hr
Topical antifungal q 6 hr (must be given 4x a day or they do not work)
Should be healed within 1-2 weeks

19
Q

What are the common causes of corneal ulcer infection (melting)?

A

Bacterial - staphylococcus, streptococcus, pseudomonas
Fungal - aspergillus

20
Q

What causes keratomalacia (melting ulcer)?

A

Secondary bacterial and/or fungal infection
Endogenous proteinases (neutrophils, corneal epithelial cells)
Previous topical corticosteroid administration

21
Q

How would you treat an infected corneal ulcer?

A

Topical atropine sulfate 1% q 8-24 hr
Topical antifungal (voriconazole 1%) q 2-6 hr
Topical antibiotic (moxifloxacin or another fluroquinolone) q 2-6 hr
Anti-melting medication (serum, EDTA 1%, topical tetracycline, N-acetylcystine) q 2-6 hr

22
Q

How long should you expect an infected ulcer take to heal?

A

Around 8 weeks

23
Q

When would you consider surgery in an infected corneal ulcer?

A

> 50% stromal depth
Rapidly progressive
Melting
No vascular response
Perforated

24
Q

What is a corneal stromal abscess?

A

Small puncture wound that seals, leaving infection and/or foreign bodies in cornea

25
Q

Will there be fluorescein stain uptake in a corneal stromal abscess?

A

No

26
Q

What are the treatment options for corneal stromal abscesses?

A

Medical management
Surgical removal
Intrastromal voriconazole injection
Penetrating keratoplasty (full thickness resection of cornea)
Posterior lamellar keratoplasty
Deep lamellar endothelial keratoplasty
Enucleation

27
Q

What is an indolent corneal ulcer?

A

Corneal ulceration for duration longer than 1-2 weeks
No signs of infection or other reasons for delayed healing
More common in older horses

28
Q

What is immune mediated keratitis?

A

Non ulcerative keratitis
Corneal opacification
Vascularization
Usually minimal to no pain

29
Q

How would you treat IMMK?

A

Topical NSAID q 8-24 hr
Nepafenac or Bromfenac (Expensive)
Topical steroids (increased risk for fungal keratitis with chronic use)
Immunomodulators - effective for superficial form

30
Q

What can IMMK progress to?

A

Lymphoma

31
Q

What is a good surgical option for IMMK?

A

Cyclosporine implant
Surgical removal

32
Q

How would you treat EHV keratitis?

A

Topical antiviral (Cidofovir)
Systemic NSAID

33
Q

What does subepithelial keratomycosis look like clinically?

A

Epithelial IMMK
Equine herpesvirus keratitis

34
Q

What would make you think subepithelial keratomycosis?

A

Pain

35
Q

How would you treat subepithelial keratomycosis?

A

Topical atropine sulfate
Topical antifungal
Topical antibiotic
Systemic NSAID as needed

36
Q

What is the most common ocular tumor?

A

Squamous cell carcinoma

37
Q

Is recurrence common in SCC?

A

Yes

38
Q

What are the risk factors for SCC?

A

Lack of pigment
Increased age
Breed predilection (Appy, Halfs, Drafts)
UV radiation
Chronic tissue inflammation/infection

39
Q

What does a SCC typically look like?

A

Thickened to raised, vascularized conjunctiva/cornea with cobble stone texture

40
Q

What is the hallmark of SCC on histopath?

A

Collagen pearls

41
Q

What is the treatment for SCC?

A

Chemotherapy
Surgery + adjunctive therapy

LA dx/tx (11 decks)

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