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Systemic Pathology > ocular pathology > Flashcards

ocular pathology Flashcards

1
Q

How to send eyeball to histopathology for best result?

A

Inject small amount of formalin (0.5 mL) into the vitreous of the eye (preserve retina):
- use 25g or smaller needle for injection
- inject close to the optic nerve
- leave the optic nerve (for orientation)

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2
Q

Location of conjunctiva

A

inside eyelid covering the sclera to the limbus

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3
Q

What are the potential infectious causes for conjunctivitis in cats?

A
  • Chlamydophila felis
  • herpesvirus
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4
Q

Infectious cause of conjunctivitis in bovine

A

Moraxiella bovis

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5
Q

Non-infectious causes of conjuctivitis

A
  • allergy
  • desiccation
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6
Q

What are conjunctivitis often associated with?

A

corneal disease

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7
Q

How does conjunctivitis react to chronic injury?

A

become more like skin (keratinization, pigmented)

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8
Q

What is this?

A

Dermoid

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9
Q

What is dermoid?

A
  • a form of choristoma: normal tissue in abnormal place
  • congenital
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10
Q

Why can dermoid be problematic?

A

can cause secondary corneal injury

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11
Q

What is the most common eyelid tumor of dogs?

A

Meibomian gland adenoma

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12
Q

What is this?

A

Meibomian gland adenoma

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13
Q

Where are meibomian gland adenoma commonly found?

A

eyelid margin

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14
Q

Characteristics of meibomian gland adenoma

A
  • benign
  • non- invasive
  • cured with excision
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15
Q

What are meibomian adenoma commonly accompanied by?

A

chalazion: local granulomatous reaction due to leakage og gland contents

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16
Q

Treatment for dermoid

A

keratectomy

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17
Q

What are the species that are predisposed to conjunctival squamous cell carcinoma?

A
  • poor pigmented breed cattle / horses
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18
Q

Characteristics of eyelid squamous cell carcinoma

A
  • infiltrative
  • have metastatic potential
  • commonly ulcerative & hemorrhagic
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19
Q

Common location of conjunctival squamous cell carcinoma in cattle

A

on bulbar conjunctiva at the limbus

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20
Q

What is the common location to find conjunctival squamous cell carcinoma in horses?

A

third eyelid

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21
Q

What is the most common location to find conjunctival squamous cell carcinoma in cats?

A

skin of the eyelid

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22
Q

Characteristic of melanocytic tumor on dogs

A

prognosis depend on location:
- eyelid margin: benign
- conjunctiva: invasive & prone to reoccurrence
- limbus: benign

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23
Q

What are some non-specific responses of the cornea to injury in the corneal stroma?

A
  • neovascularization
  • edema
24
Q

What are some non-specific responses of the cornea to injury in the corneal epithelium?

A

pigmentation (dogs common)

25
Q

How are corneal stroma kept in dehydrated state?

A

Energy-dependent sodium pump:
- in endothelium
- removing solute from the corneal stroma (osmotic gradient)
Tight intra-cellular junction:
- epi- & endothelium

26
Q

How does cornea get its nutrients if it is avascular?

A
  • rely on passive diffusion of nutrients & oxygen from conjunctival & scleral blood vessel, tear film & aqueous humor
27
Q

What are the factors that favors healing of the corneal injury?

A
  • one time injury
  • shallow defect
  • healthy stroma
  • no sepsis
  • normal tear film
  • epithelial promoting growth factors
28
Q

What are the factors promoting corneal scarring formation

A
  • ongoing injury
  • deep defect
  • damaged stroma
  • sepsis
  • numerous neutrophils
  • deficient/altered tear film
    fibroblast growth factor predominates
29
Q

Corneal ulcer definition

A

loss of corneal epithelium +/- some of the stroma

30
Q

The 4 layers of the cornea

A
  • corneal epithelium
  • basement membrane
  • Descemet’s membrane
  • corneal endothelium
31
Q

Characteristics of superficial ulcer

A

minimal corneal stroma affected

32
Q

Quality of corneal epithelium

A

hydrophobic

33
Q

Quality of Decemet’s membrane

A

hydrophobic

34
Q

Quality of corneal stroma

A

hydrophilic

35
Q

How does fluorescent stain diagnose corneal ulcer?

A

corneal epithelium is hydrophobic while corneal stroma is hydrophilic
- hence stain sticks to corneal stroma

36
Q

What do breaks in the corneal epithelium lead to?

A

stromal edema through absorption of tear film (tear & neutrophil)

37
Q

What happens if the corneal ulceration is minor?

A
  • corneal epithelium slides over the defect, providing a barrier
  • mitosis in 24 h
38
Q

What is necessary for the healing of cornea to be successful?

A

corneal epiuthelium must be able to adhere to underlying stroma

39
Q

What can be the result of deep corneal ulcer?

A

exposition of the Decemet’s membrane resulting in decemetocele

40
Q

Why is decemetocele an emergency?

A

thin cornea prone to rupture

41
Q

What is keratoconjunctivitis sicca?

A

dry eye; decrease quantity of tears

42
Q

What causes keratoconjunctivitis sicca?

A

auto-immune disease targeting the lacrimal gland

43
Q

Characteristics of keratoconjunctiva sicca

A
  • potentially progressive
  • chronic trauma due to desiccation (epidermalization of the cornea)
  • minimal corneal edema of the ulceration
44
Q

What species are commonly affected by fungal keratitis?

A

horses

45
Q

What causes fungal keratitis in horses?

A

iatrogenic following treatment of a corneal ulcer

46
Q

What is often the pathogenic agent fro equine fungal keratitis?

A

Aspergillus spp

47
Q

What does fungal keratitis often lead to?

A

keratomalacia

48
Q

Why are superficial scraping/biopsies usually non-diagnostic of fungal keratitis in horses?

A

fungus usually found in deep cornea

49
Q

What does herpesvirus often cause in kittens?

A

conjunctivitis

50
Q

What does herpesvirus often cause in adult cats?

A

keratitis

51
Q

Common presentation of herpesvirus in cats

A
  • keratoconjunctivitis with purulent discharge
  • accompanied by rhinotracheitis
52
Q

What type of ulceration does herpesvirus cause on the cornea?

A

multifocal to coalescing punctate ulcer (dendritic ulcer

53
Q

What causes infectious bovine keratoconjunctivitis

A

Moraxella bovis transmitted by fly vector & fomite

54
Q

What can increase the severity of infectious bovine keratoconjunctivitis?

A

co-infection with IBR

55
Q

How does bovine infectious keratoconjunctivitis cause corneal ulcer?

A
  • bacteria invade epithelium causing small ulcer
  • stromal exposure causes increase in neutrophil at the site
  • keratomalacia
  • healing via scarring

Systemic Pathology (2 decks)

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