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Small Animal Optho/Neuro > Corneal Ulceration and Perforation > Flashcards

Corneal Ulceration and Perforation Flashcards

1
Q

what are the 4 layers of the cornea?

A
  1. epithelium
  2. stroma
  3. descemet’s membrane
  4. endothelium
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2
Q

What is critical to the function of the stroma?

A

clarity

the stroma accounts for 90% of thickness of the cornea. Its composed of lamellar collagen and is normally avascular.

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3
Q

How is corneal clarity manintained?

A
  1. non-keratinized epithelium
  2. regular stromal collagen arrangment
  3. small diameter collagen fibrils
  4. lack of blood vessels
  5. relative dehydration
  6. pre-corneal tear film
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4
Q

What are the 5 general causes of corneal ulcers?

A
  1. corneal abrasion due to adnexal dz
  2. tear film deficiency
  3. exposure keratitis
  4. infection
  5. trauma
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5
Q

T/F: acute superficial, mid-stromal, and deep-stromal corneal ulcers all have the potential to heal with medical management

A

true

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6
Q

T/F: desmetoceles and corneal perforations can heal with medical management

A

false

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7
Q

under normal circumstances, the cornea heals within _____ days.

A

7-10, but often much faster.
this healing timeline can be altered by many factors.

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8
Q

What diagnostics should you run on suspected corneal ulcer cases?

A
  1. search for underlying cause
  2. schirmer tear test
  3. fluorescein stain
  4. corneal cytology + culture

1 & 2 = always
3 = usually
4 = specific indications

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9
Q

what are specific causes of DELAYED corneal healing? (there are 6)

A
  • corneal infection
  • unresolved source of corneal abrasion
  • keratoconjunctivitis sicca
  • exposure keratitis
  • neurotrophic keratitis
  • SCCED
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10
Q

Primary infectious corneal ulcers in cats are typically caused by ________.

A

herpesvirus

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11
Q

Secondary bacterial/fungal infections can occur after a corneal ulcer develops. These impair healing and result in …

A

progressive destruction of the corneal stroma causing increasing size and depth of the ulcer.

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12
Q

__________ is the inward rolling of the eyelids causing hair to abrade the cornea. It can be conformational or spastic.

A

entropion

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13
Q

_________ is single or mulitple abnormal hairs protruding from meiobomian gland openings of the eyelids. They may or may not cause clinical problems.

A

distichia

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14
Q

____________are abnormal hairs protruding through conjunctival surface of the eyelid. They are always symptomatic and common in young and/or toy breed dogs.

A

ectopic cilia

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15
Q

___________ is a common cause of corneal ulcers and delayed healing in dogs. There is usually copious mucopurulent ocular discharge.

A

keratoconjunctivitis sicca

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16
Q

how do you diagnose keratoconjunctivitis sicca?

A

shirmer tear test

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17
Q

Dogs who have bug eyes, facial paralysis, orbital disease causing exophthalmos, and glaucoma causing buphthalmos ALL are at risk for what condition to develop?

A

exposure keratitis

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18
Q

___________ is a rare degenerative corneal dz caused by impairment of the ophthalmic branch of the trigeminal n. leading to corneal epithelial breakdown, impairment of healing, and development of corneal ulceration.

A

neurotrophic keratitis

19
Q

_________- is characterized by a chronic non-heaing superficial corneal ucler for which NO underlying cause can be determined. It is common in middle-aged dogs and is also called ‘boxer ulcer’.

A

spontaneous chronic corneal epithelial defect (SCCED)

20
Q

what are the goals of medical treatment for corneal ulcers?

A
  1. prevent/control infection
  2. prevent/control collagenolysis
  3. increase patient comfort
  4. promote corneal healing
21
Q

You have just diagnosed a patient in your clinic with an acute superficial corneal ulcer. What is your treatment plan?

A
  1. topical broadspec Abs (neopolybac)
  2. topical atropine
  3. analgesic PRN (oral NSAID)
22
Q

You have just diagnosed a patient in your clinic with an acute superficial corneal ulcer. You sent them home with Abs, atropine, and NSAIDs. What are your follow-up recommendations?

A
  1. recheck in 2-3 days
  2. flourescein stain to monitor the ulcer size
23
Q

You have just diagnosed a patient in your clinic with an chronic superficial corneal ulcer. This patient initially presented 12 days ago with an acute ulcer. What is your plan?

A

First, search for an underlying cause for NON-HEALING (infection, abrasion, KCS, exposure keratitis, neurotrophic keratitis, SCCED), as well as the corneal ulcer etiology.

Once those things are determined, you can decide on medical or surgical tx.

24
Q

What are the clinical characteristics of SCCED?

A
  1. chronic superficial corneal ulcer that may change in size, but does not completely heal with medical therapy
  2. epithelial lip flourescein stain pattern
  3. variable pain and vascularization
  4. RARELY becomes infected
25
Q

What is the pathogenesis of SCCED?

A

Hyalinized acellular anterior corneal stroma prevents corneal epithelial adhesion

26
Q

How do you treat SCCED?

A
  1. epithelial debridement
  2. surgical – grid keratotomy or burr keratotomy OR superficial keratectomy
27
Q

T/F: topical antibiotics are indicated in cases of SCCED until corneal ulcer heals.

A

true
should heal in 10-14 days

28
Q

T/F: you can usually perform epithelial debridement with topical anesthetic alone

A

true

29
Q

T/F: debridement alone is sufficient to achieve healing in dogs with SCCED

A

false – not alone.

30
Q

What is the purpose of grid or burr keratotomies?

A

they penetrate the zone of hyalinized anterior corneal stroma and allow for exposure to type I collagen to facilitate epithelial adhesion complex formation

31
Q

How do you perform a grid keratotomy?

A

use a 25g needle and lightly scratch across the ulcer bed at a low angle.
begin and end in normal epithelium and have the scratches 1 mm apart.

32
Q

You performed a grid keratotomy on your patient with SCCED. What post-operative care are you going to recommend?

A
  1. topical antibiotic 3-4x/day until healed (10-14d)
  2. e-collar
  3. recheck in 1 week; if not healed by 2-3 weeks, repeat procedure. May require up to 6 weeks for complete development of epithelial adhesion complex.
33
Q

T/F: debridement alone can be effective for non-healing superficial ulcers in cats that are caused by feline herpesvirus

A

true; however grid/bur keratotomy may be used to induce corneal sequestrum formation

34
Q

What diagnostics should you run to diagnose a mid-stromal and deep stromal ulcers?

A
  1. look for underlying factors
  2. corneal c/s
  3. corneal cytology
35
Q

You have just diagnosed your patient with a mid-stromal ulcer. What is involved in your treatment plan?

A
  1. Topical antibiotic SOLUTION (broad spec or c/s; apply q4-6hr)
  2. protease inhibitor (systemic tetracycline – minocycline or doxycycline)
  3. topical atropine to maintain dilated pupil
  4. analgesic PRN
  5. recheck q24hr, then 48 hr
36
Q

How do you treat deep stromal and melting ulcers?

A
  1. topical antibiotic solution (broad spec or c/s) q 2-4hr
  2. protease inhibitors (systemic tetracycline or topical autogenous serum q2-4hr)
  3. analgesic PRN
  4. hospitalize patient to continue frequent tx or recheck in 24 hr
37
Q

T/F: desmetoceles are surgical cases

A

true

38
Q

what 2 diagnostics are important for the diagnosis of descemetocoeles but you must use extreme caution with them?

A
  1. corneal cytology or culture from ulcer edges
  2. STT
39
Q

how do you treat a descemetocoele?

A
  1. conjunctival flap
    or
  2. corneoconjunctival transposition

both are usually referral surgeries.

post-operatively:
1. topical antibiotics
2. E-collar
3. +/- proteolytic inhibitors
recheck at 1 week, then 3 weeks
d/c antibiotics 3 wks post-op
trim flap pedicle 4-6 wks post-op

40
Q

T/F: corneal perforation can be treated with antibitoics, proteolytic inhibitors, and systemic analgesia.

A

false – this is a surgical condition.
you treat pre-operatively with topical broad spec antibiotics q4-6hr, topical atropine q6-8hr, systemic broad spec antibiotics, and systemic antiinflammatories
but this is followed by surgery!

41
Q

T/F: with appropriate management, corneal ulcers generally have a very good prognosis

A

true

42
Q

what are clinical signs of corneal ulceration?

A
  • blepharospasm
  • epiphora
  • conjunctival hyperemia
  • chemosis
  • variable ocular discharge
43
Q

T/F: topical corticosteroids are contraindicated in presence of corneal uclers

A

true

44
Q

what is the purpose of conjunctival flaps?

A
  1. mechanical support
  2. immediate blood supply
  3. source of fibroblasts
  4. source of epithelial cells

Small Animal Optho/Neuro (12 decks)

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