ocular pathology

Question 1

How to send eyeball to histopathology for best result?

Answer 1

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)

Question 2

Location of conjunctiva

Answer 2

inside eyelid covering the sclera to the limbus

Question 3

What are the potential infectious causes for conjunctivitis in cats?

Answer 3

• Chlamydophila felis
• herpesvirus

Question 4

Infectious cause of conjunctivitis in bovine

Answer 4

Moraxiella bovis

Question 5

Non-infectious causes of conjuctivitis

Answer 5

• allergy
• desiccation

Question 6

What are conjunctivitis often associated with?

Answer 6

corneal disease

Question 7

How does conjunctivitis react to chronic injury?

Answer 7

become more like skin (keratinization, pigmented)

Question 8

What is this?

Answer 8

Dermoid

Question 9

What is dermoid?

Answer 9

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

Question 10

Why can dermoid be problematic?

Answer 10

can cause secondary corneal injury

Question 11

What is the most common eyelid tumor of dogs?

Answer 11

Meibomian gland adenoma

Question 12

What is this?

Answer 12

Meibomian gland adenoma

Question 13

Where are meibomian gland adenoma commonly found?

Answer 13

eyelid margin

Question 14

Characteristics of meibomian gland adenoma

Answer 14

• benign
• non- invasive
• cured with excision

Question 15

What are meibomian adenoma commonly accompanied by?

Answer 15

chalazion: local granulomatous reaction due to leakage og gland contents

Question 16

Treatment for dermoid

Answer 16

keratectomy

Question 17

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

Answer 17

• poor pigmented breed cattle / horses

Question 18

Characteristics of eyelid squamous cell carcinoma

Answer 18

• infiltrative
• have metastatic potential
• commonly ulcerative & hemorrhagic

Question 19

Common location of conjunctival squamous cell carcinoma in cattle

Answer 19

on bulbar conjunctiva at the limbus

Question 20

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

Answer 20

third eyelid

Question 21

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

Answer 21

skin of the eyelid

Question 22

Characteristic of melanocytic tumor on dogs

Answer 22

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

Question 23

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

Answer 23

• neovascularization
• edema

Question 24

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

Answer 24

pigmentation (dogs common)

Question 25

How are corneal stroma kept in dehydrated state?

Answer 25

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

Question 26

How does cornea get its nutrients if it is avascular?

Answer 26

- rely on passive diffusion of nutrients & oxygen from conjunctival & scleral blood vessel, tear film & aqueous humor

Question 27

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

Answer 27

- one time injury - shallow defect - healthy stroma - no sepsis - normal tear film - epithelial promoting growth factors

Question 28

What are the factors promoting corneal scarring formation

Answer 28

- ongoing injury - deep defect - damaged stroma - sepsis - numerous neutrophils - deficient/altered tear film fibroblast growth factor predominates

Question 29

Corneal ulcer definition

Answer 29

loss of corneal epithelium +/- some of the stroma

Question 30

The 4 layers of the cornea

Answer 30

- corneal epithelium - basement membrane - Descemet's membrane - corneal endothelium

Question 31

Characteristics of superficial ulcer

Answer 31

minimal corneal stroma affected

Question 32

Quality of corneal epithelium

Answer 32

hydrophobic

Question 33

Quality of Decemet's membrane

Answer 33

hydrophobic

Question 34

Quality of corneal stroma

Answer 34

hydrophilic

Question 35

How does fluorescent stain diagnose corneal ulcer?

Answer 35

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

Question 36

What do breaks in the corneal epithelium lead to?

Answer 36

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

Question 37

What happens if the corneal ulceration is minor?

Answer 37

- corneal epithelium slides over the defect, providing a barrier - mitosis in 24 h

Question 38

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

Answer 38

corneal epiuthelium must be able to adhere to underlying stroma

Question 39

What can be the result of deep corneal ulcer?

Answer 39

exposition of the Decemet's membrane resulting in decemetocele

Question 40

Why is decemetocele an emergency?

Answer 40

thin cornea prone to rupture

Question 41

What is keratoconjunctivitis sicca?

Answer 41

dry eye; decrease quantity of tears

Question 42

What causes keratoconjunctivitis sicca?

Answer 42

auto-immune disease targeting the lacrimal gland

Question 43

Characteristics of keratoconjunctiva sicca

Answer 43

- potentially progressive - chronic trauma due to desiccation (epidermalization of the cornea) - minimal corneal edema of the ulceration

Question 44

What species are commonly affected by fungal keratitis?

Answer 44

horses

Question 45

What causes fungal keratitis in horses?

Answer 45

iatrogenic following treatment of a corneal ulcer

Question 46

What is often the pathogenic agent fro equine fungal keratitis?

Answer 46

Aspergillus spp

Question 47

What does fungal keratitis often lead to?

Answer 47

keratomalacia

Question 48

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

Answer 48

fungus usually found in deep cornea

Question 49

What does herpesvirus often cause in kittens?

Answer 49

conjunctivitis

Question 50

What does herpesvirus often cause in adult cats?

Answer 50

keratitis

Question 51

Common presentation of herpesvirus in cats

Answer 51

- keratoconjunctivitis with purulent discharge - accompanied by rhinotracheitis

Question 52

What type of ulceration does herpesvirus cause on the cornea?

Answer 52

multifocal to coalescing punctate ulcer (dendritic ulcer

Question 53

What causes infectious bovine keratoconjunctivitis

Answer 53

Moraxella bovis transmitted by fly vector & fomite

Question 54

What can increase the severity of infectious bovine keratoconjunctivitis?

Answer 54

co-infection with IBR

Question 55

How does bovine infectious keratoconjunctivitis cause corneal ulcer?

Answer 55

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