07 - diseases of the cornea

Question 1

layers of the cornea

what are the 6 layers of the cornea (first one is tear film…)

Answer 1

1. tear film
2. epithelium
3. basement membrane
4. stroma
5. Descemet membrane (doesn’t take up fluorescein stain)
6. endothelium

Question 2

1-3. what are three corneal responses to insult?

Answer 2

1. edema
2. vascularization (normal cornea doesn’t have blood vessels)
3. pigmentation (chronic irritation)

Question 3

what is keratitis?

Answer 3

inflammation of the cornea

Question 4

(keratoconjuctivitis sicca)

1. what is this?

Answer 4

1. inflammation of the cornea and conjuctiva as a result of low aqueous component of tear film

Question 5

(keratoconjuctivitis sicca)

1-7. causes?

Answer 5

1. immune mediated destruction of tear glands
2. congenital (gland aplasia)
3. iatrogenic (excision of nictitans gland)
4. drug induced
5. trauma (proptosis)
6. neurogenic
7. infection (distemper in dogs, herpesvirus)

Question 6

(keratoconjuctivitis sicca)

1-4. Cx?

Answer 6

1. ocular irritation/pain
2. conjunctivitis…
3. keratitis…
4. ocular discharge

Question 7

(KCS)

1. what test is helpful to dx?

Answer 7

1. schirmer tear test

Question 8

(KCS)

1-3. 3 treatment options?

Answer 8

1. cyclosporine -> reduce immune destruction of tear producing glands
2. pilocarpine -> stimulate tear production
3. parotid duct transposition

Question 9

(ulcerative keratitis)

1. use what to demonstrate ulcer?

Answer 9

1. fluorsecien stain (descemet’s membrane doesn’t stain!)
2. swab for culture

Question 10

(superficial corneal ulcers)

1. treat initially with broad spec abx -> will typically heal in 3-5 days -> if it doesn’t what does this mean?

Answer 10

1. cause for ulcer still present, ulcer is infected, indolent ulcer present

Question 11

1. what is an indolent ulcer?
2. cause in dogs?
3. in cats?

Answer 11

1. slow-healing ulcer
2. failure of epi to adhere to basement membrane (in dogs)
3. FHV-1

Question 12

(indolent ulcer)

1. treatment for dogs?
2. for cats?

Answer 12

1. debride and grid keratotomy
2. don’t do grid keratotomy -> can lead to corneal sequestrum

Question 13

(midstromal corneal ulcer)

1. potentially more serious

Question 14

(deep corneal ulcer)

1. why should it be treated as emergency?
2. tx?

Answer 14

1. perforation can occur
2. surgical repair (conjuctival pedicle flap)

Question 15

(herpesvirus keratitis)

1. common in what species?
2. conjuctivitis with or without corneal ulcer
3. tx?

Answer 15

1. cat
2. topical antiviral medication

Question 16

(nonulcerative keratitis)

(chronic superficial keratitis)

1. predisposed breeds?
2. cause?
3. Cx?
4. tx?
5. aka?

Answer 16

1. german shephard, greyhound, border collie
2. immune mediated
3. vascularization, inflammation, granulation
4. topical cyclosporine/corticosteroids
5. pannus

Question 17

(nonulcerative keratitis)

(eosinophilic keratitis)

1. unique for what species?
2. corneal lesions are pink and raised with white adherent material
3. dx?
4. tx?

Answer 17

1. cats
2. surface scrapings show ^ eosinophils
3. topical steroids

Question 18

(non-ulcerative keratitis)

(corneal sequestrum)

1. unique to what species?
2. tx?
3. cause?

Answer 18

1. cats (persians)
2. leave alone to slough (can perforate)
3. chronic irritation