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SEM 5: SAM 1 > The Cornea > Flashcards

The Cornea 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

Why is the cornea clear?

A
  1. Avascular
  2. Non-myelinated nerves
  3. Dehydrated
  4. Ordered cell arrangement
  5. Non pigmented
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3
Q

What do lipids on the cornea look like, and what is it suggestive of?

A

shiny, bilateral, crystalline

indicative of corneal dystrophy

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4
Q

What are the possible causes of corneal edema resulting in a blue opacity of the cornea?

A
  1. Epithelial barrier disruption (tear film entry into hydrophilic stroma)
  2. Endothelial barrier/pump dysfunction (Focal loss, reduction in number, reduction in function)
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5
Q

What is an example of corneal edema resulting from generalized reduction in function of endothelial cells?

A
  • Glaucoma
  • Uveitis
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6
Q

What is an example of corneal edema resulting from generalized reduction in number of endothelial cells?

A

Senile endothelial degeneration

(Edema displays a fluffy and disorganized pattern)

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7
Q

What does a red corneal opacity indicate?

A

Corneal neovascularization

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8
Q

What are causes of superficial neovascularization resulting in red opacity of the cornea?

A

Anything that irritates the surface of the eye

Ex: KCS, entropion, hair abnormalities, superficial corneal ulcers

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9
Q

What are causes of deep neovascularization resulting in red opacity of the cornea?

A
  • Uveitis
  • Glaucoma
  • Deep corneal ulcer / inflammation
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10
Q

What does ciliary flush indicate, and how does the eye appear?

A

360 degree red halo around the cornea, indicates deep neovascularization (uveitis, glaucoma, deep corneal ulcer/inflammation)

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11
Q

What color change of the cornea can be seen with corneal fibrosis?

A

White with gray or wispy features

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12
Q

What causes the cornea to appear chalky white?

A

Calcific corneal degeneration

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13
Q

What color change to the cornea is indicative of corneal infection?

A

White with green or yellow hues (WBC infiltrates)

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14
Q

List the 4 brachycephalic risk factors for corneal ulcers

A
  1. Ocular prominence (bug eyes)
  2. Decreased corneal sensitivity
  3. Adnexal abnormalities (lagophthalmos, trichiasis, distichia, etc)
  4. Tear film abnormalities (prone to dry eye)
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15
Q

What is the definition of a uncomplicated/simple corneal ulcer?

A

A superficial ulcer that heals in 7 days or less

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16
Q

What are causes of delayed corneal ulcer healing, resulting in a complex/complicated ulcer?

A
  • Indolent ulcers
  • Persistent irritation
  • Infection
16
Q

What is the treatment protocol for a patient with an uncomplicated superficial corneal ulcer?

A
  • E collar
  • Topical Abx TID/QID (neopolyBAC, Tobramycin)
  • Atropine
  • NSAIDs/Tramadol/GABA
  • Recheck 5-7 days
16
Q

What is the definition of a complicated/complex corneal ulcer?

A

A superficial corneal ulcer that takes longer than 7 days to heal

17
Q

Why do indolent ulcers result in delayed healing?

A

Lack of epithelial adherence to stroma (lack of hemidesmosomes)

18
Q

How can indolent ulcers be diagnosed?

A
  • Test epithelium with q-tip
  • Indolent ulcers have epithelium that is easily peeled off/debrided with q-tip
  • Fluorescein staining results in a halo extending beyond epithelial margins
19
Q

What dog breed is most susceptible to indolent ulcers?

A

Boxers

20
Q

What is the treatment protocol for indolent ulcers?

A

Medical management: Topical Abx, Atropine, NSAIDs
1. Debridement with q tip (50% chance of healing within 2 weeks)
If not healed by 2 weeks…
2. Anterior stromal puncture
3. Diamond burr debridement
4. Recheck in 2 weeks

21
Q

When is anterior stromal puncture and diamond burr debridement contraindicated?

A

If ulcers with signs of infection

(Never do if suspect infection!!)

22
Q

What is the most common cause of corneal infection in cats?

A

Feline herpesvirus

(bacterial and fungal can be causes too)

23
Q

What corneal ulcers have concurrent corneal infection, 99% of the time?

A

Deep (stromal) corneal ulcers

24
Q

What is the pathogenesis behind corneal infection?

A

Bacteria (most commonly) or fungal organisms results in collagenolysis and keratomalacia

25
Q

What bacterial organisms are most commonly involved in corneal infections?

A
  1. Pseudomonas (most common cause of melting corneal ulcers)
  2. Staph
  3. Strep
26
Q

What are common clinical findings in patients with corneal perforation?

A
  1. Positive Seidel test (active leaking)
  2. Wrinkled cornea
  3. Shallow anterior chamber
  4. Iris prolapse
  5. Fibrin plug
  6. Hyphema
27
Q

What tests should NOT be performed in patients with deep corneal ulcers?

A
  • No STT or IOP (painful)

(can perform in normal eye tho)

28
Q

Why is proparacaine never sent home for management of corneal ulcers?

A

Repeated use is toxic to the cornea, may result in melting ulcer

29
Q

What indications require surgical treatment of corneal ulcers?

A
  1. > 50% stromal loss or severe infection
  2. If refractory to medical therapy
  3. If descemetocele or perforation
30
Q

When are systemic antibiotics indicated for treatment of deep corneal ulcers?

A
  1. Well vascularized ulcer
  2. Corneal perforation
  3. Post conjunctival flap surgery
31
Q

What options are available for medical management of corneal ulcers?

A
  1. Topical Abx (Cephalosporins, Fluoroquinolones)
  2. Autologous serum
  3. Topical atropine
  4. NSAIDs
32
Q

What ulcers always require referral for surgical correction?

A
  1. Corneal perforation
  2. Descemetocele
33
Q

What is the cause of greasy/tan punctate opacities on the cornea?

A

Keratic precipitates - common with uveitis

SEM 5: SAM 1 (35 decks)

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