Eye Pathology I

Question 1

What are the main functions of the eyelid?

Answer 1

• Protection
• Distribution of the tear film
• removal of excess tears and foreign material

Question 2

What are the fornices?

Answer 2

Areas where the conjunctiva forms small pockets

Question 3

What are the two main functions of the conjunctiva?

Answer 3

• Secretory- mucous contributions to the tear film
• Immunity- CALT which is part of the mucousal associated lymphoid tissue system
• Stem Cells that migrate from the conjunctiva to the site of injury

Question 4

What are the two types of lymphoid tissue found in the eye?

Answer 4

• Mucousal
• Diffuse lymphoid tissue

Question 5

What occurs to the antigen in mucousal lymphocytes?

Answer 5

• The antigen is taken up by APC’s and then presented to the lymphocytes

Question 6

What cells are mainly in the diffuse lymphoid tissue?

Answer 6

Mainly cytotoxic CD8+ cells
Plasma cells that produce igA antibodies

effector tissue

Question 7

What is the gross appearance of the conjunctiva?

Answer 7

• Smooth
• Shiny
• Can be pigmented
• Visible mobile blood vessels (salmon pink colour but is its whiter over the globe)

Question 8

What is the main function of the sclera?

Answer 8

• External support to the globe contents
• movement of globe acts as an insertion point for extraocular muscles

Question 9

What is the function of the third eyelid?

Answer 9

• Protection of the cornea
• Distribution of the tear film
• Nicitans gland contributes around 30-40% of the aqueous component of the tear film

Question 10

What composes the lacrimal system?

e.g the two main functions

Answer 10

Tear Production and tear drainage

Question 11

What are the three components of the tear film?

Answer 11

• Mucus- goblet cells in the conjunctiva
• Aqueous- lacrimal gland in the upper eyelid and nicitans gland in the third eyelid
• Lipid- meibomian glands on the eyelid margin

Question 12

What are meibomian glands?

Answer 12

large sebaceous glands present in the eyelids which secrete lipids that form the superficial layer of the tear film

Question 13

What are the four functions of the tear film?

Answer 13

1. Lubrication
2. Immune modulation
3. removal of debris
4. Nutrition to the cornea

Question 14

What is endotropion?

Answer 14

Internal rolling in of the eyelid

Question 15

What is ectropion?

Answer 15

External rolling out of the eyelid

Question 16

What causes endotropion/ ectropion?

Answer 16

• Congenital
• Developmental
• Trauma
• Inflammation
• Iatrogenic (poor surgical technique)

Question 17

What is distichia?

Answer 17

• abnormal hairs arising from the meibomian gland and exciting out of the eyelid margin

Question 18

What is ectopic cillia?

Answer 18

Abnormal hairs arising from the meibomian gland but exciting out of the palpebral conjunctiva

Question 19

What is blepharitis?

Answer 19

Inflammation of the eyelids

Question 20

What is chalazonian?

Answer 20

small lump or cyst develops on the eye due to a blocked oil gland
* response to the leakage of meibomian gland secretions
* leakage of lipid into the subconjunctival space
* chronic inflammation leads to calcification of the gland and surrounding tissue

Question 21

What is a stye?

Answer 21

Suppurative inflammation of the adnexal glands

Question 22

What causes parasitic blepharitis?

Answer 22

Demodex and sarcoptes scabei

Question 23

What causes idiopathic blepharitis?

Answer 23

• Predominantly macrophages and neutrophils
• it is not associated with adnexal structures and there is no identifiable agent

Question 24

What is the protrusion of the nicitans gland also called?

Answer 24

Cherry eye

Question 25

What happens when there is a decrease in laxity of the ligament that holds the nicitans gland in place?

Answer 25

Nicitans gland 'pops' out causes cherry eye

Question 26

What are the two causes of conjunctivitis?

Answer 26

* Infectious- e.g bacterial, viral * non-infectious- allergies, environmental irritants

Question 27

What is the most common cause of non-infectious canine conjunctivitis?

Answer 27

Dry eye is the most common in dogs local irritation is also common | any type of eyelid abnormality

Question 28

What is the main virus that causes conjunctivitis in cats?

Answer 28

Feline Herpes Virus

Question 29

What is Infectious Bovine Keratoconjunctivitis?

Answer 29

* Caused by Moraxella bovis * causes 'pink-eye' * pilli allow epithelial treatment

Question 30

What is Immune-Mediated Keratoconjunctivitis Sicca?

Answer 30

the body recognises self-antigens in the lacrimal gland starts a T-Cell response against the antigens decreases the tear film quantity and quality

Question 31

When should you use a schirmer tear test?

Answer 31

in all mucky and red eyes

Question 32

What are some common causes of dry eye?

Answer 32

* Developmental KCS * Metabolic * Neurological Inflammation/ Infection

Question 33

What species usually gets retained spectacles and why?

Answer 33

Snakes * due to poor environment * lack of correct humidity

Question 34

What is the difference between a stye and a chalazonian?

Answer 34

* Chalazonian is granulomatous inflammation * Stye is Suppurative inflammation

Question 35

What does Feline Herpes Virus Cause in cats?

Answer 35

* Conjunctivitis * Keratitis * Upper Respiratory Disease in Young Cats

Question 36

What may cause blepharitis?

Answer 36

* Bacterial * Mycotic * Parasitic * Protozoal * Immune-mediated

Question 37

What are the clinical signs of conjunctivitis?

Answer 37

* Hyperaemic/ Edematous coonjunctiva (vasodilation/ increased blood flow) * Lymphoid follicles * Ulceration * Fibrosis

Question 38

What does FHV-1 cause in cats?

Answer 38

* Conjunctivitis * Keratitis * URD * Superficial ulcers

Question 39

What is the pathogenesis of the T-Cell response in immune mediated sicca?

Answer 39

* immune system becomes overeactive and starts attacking its own tissues * white blood cells accuulate in the lacrimal gland * inflammation of the lacrimal gland * ability to produce tears is diminished

Question 40

What are the results of the schirmer tear test?

Answer 40

* Less than 10= insufficient tear production * 20= normal tear production