Equine Corneal Disease

Question 1

list the layers of the cornea from superficial to deep

Answer 1

epithelium -> stroma -> descemets membrane -> endothelium

Question 2

Ulcerative keratitis is __ common and can be categorized as __, __ or __

Answer 2

Ulcerative keratitis is very common and can be categorized as superficial, stromal or descemetocele

Question 3

how do you diagnose and treat ulcerative keratitis?

Answer 3

First you need to block the eye and then check for an underlying cause, culture/cytology the eye and fluorescein stain the eye. Based on the categorization of the ulcer you will either medically manage with topical antibiotics/atropine/NSAIDs/antiproteases or you may need to pursue surgical management.

Question 4

what types of ulcerative keratitis are often surgical?

Answer 4

Melting ulcers and desmetoceles

Question 5

what are the goals of therapy with cases of ulcerative keratitis?

Answer 5

1. controls corneal infection
2. inhibits corneal proteolysis
3. manage secondary uveitis
4. increase patient comfort

Question 6

why would you apply atropine to the eye of a horse with ulcerative keratitis?

Answer 6

in cases of ulcerative keratitis (you may also assume they have reflex uveitis) the eyes may be miotic and/or the ciliary body spasming so atropine helps relax the ciliary body giving them pain relief

Question 7

what are some surgical procedures that may be used to treat ulcerative keratitis?

Answer 7

stromal antimicrobial injection
keratectomy
conjunctival flap

Question 8

Corneal Perforations are __ surgical. what are the clinical findings?

Answer 8

ALWAYS surgical

iris prolapse/fibrin
corneal edema
hyphema/hypopyon

Question 9

T/F: ointments should be used for corneal perforations

Answer 9

F, use topical solutions, ointments are contraindicated in perforations

Question 10

list a few things that worsen the prognosis of corneal perforations

Answer 10

blunt trauma etiology
ulcerative etiology
endophthalmitis
severe hyphema
lens rupture
chronic rupture

Question 11

Explain Corneal Abscesses

Answer 11

These can be very small but very painful and will appear as a yellow-white stromal opacity with severe ocular discomfort and secondary uveitis. Medical management is similar to ulcers but you must vascularize it to heal so avoid steroids. Surgical excision with a conjunctival flap is the quicker resolution option

Question 12

band keratopathy

Answer 12

This is a corneal mineralization/calcification that is degenerative and often associated with chronic uveitis. Typically its non-painful and doesn’t require treatment unless sloughing occurs

Question 13

Immune Mediated Keratitis is chronic __ painful or __ painful and often __lateral.

Answer 13

Immune Mediated Keratitis is chronic non painful or minimally painful and often unilateral.

Question 14

what are the 4 clinical manifestations of IMMK?

Answer 14

Epithelial
Superficial stromal
Mid stromal
Endothelial

Question 15

Epithelial IMMK

Answer 15

mutlifocal punctate to coalescing non ulcerated epithelial opacities typify this form of IMMK. No attendant vascularization and minimal to no discomfort is typical

Question 16

Superficial Stromal IMMK

Answer 16

Stromal haze, vascularization and cellular infiltrate (slight green/yellow appearance) typical of stromal IMMK

Question 17

Mid Stromal IMMK

Answer 17

stromal haze, vascularization and cellular infiltrate (green/yellow) typical of stromal IMMK

Question 18

Endothelial IMMK

Answer 18

Severe regional or more commonly diffuse corneal edema

Question 19

How should you treat IMMK medically?

Answer 19

Medical management with topical steroids or cyclosporine is a lifelong treatment with some efficacy for epithelial and stromal forms of disease but ineffective for the endothelial form

Question 20

Surgical treatment of IMMK

Answer 20

Lesion excision for stromal forms of disease can be curative or you can place cyclosporine implants for 1 year or photodynamic therapy