Lacrimal System

Question 1

What glands provide the aqueous layer of the tear film?

Answer 1

Lacrimal gland

Gland of third eyelid

Question 2

How do you diagnose production of aqueous layer?

Answer 2

Superficial corneal and conjunctival inflammation = keratoconjunctivitis

Schirmer tear test I
<15mm wetting/minute = sicca (dry)

Question 3

What are causes of quantitative KCS?

Answer 3

• Immune mediated destruction of lacrimal tissue *

Excision of third eyelid gland

Parasympathetic nerve lesions

Canine distemper

Drugs - atropine and sulfa drugs, anesthetics

Question 4

What breeds are susceptible to KCS?

Answer 4

Small toy breeds

Cocker spaniel
Yorkshire terriers
West highland terrier
Bulldogs

Question 5

T/F: KCS is usually bilateral

Answer 5

True

Question 6

Clinical signs associated with acute KCS?

Answer 6

Mucopurleunt discharge

Blepharitis

Keratitis (superficial corneal neovascualrization) — seen dorsally first as tear film settles to ventral cornea

Conjunctivitis ( conjunctival hyperemia)

Question 7

Chronic clinical signs due to KCS?

Answer 7

Corneal pigmentation

Question 8

Treatment for KCS?

Answer 8

Topical cyclosporine — lifelong therapy

Tcell inhibitor and prevents destruction of lacrimal tissue
Anti-inflammatory effects
Should see response in 4-6weeks

Question 9

What can you try to give a patient for KCS if they are unresponsive to cyclosporine A?

Answer 9

Tacrolimus (ophthalmic)

Question 10

What are the 4 objectives of KCS treatment?

Answer 10

Replace tears (lubricate with artificial tear ointment)

Simulate more tears
Anti inflammatory
(Cyclosporine)

Antibiotic
- clear infection while tear film recovers

Question 11

What is the cause of neurogenic KCS?

Answer 11

Loss of PSNS innervation to lacrimal gland and ispilateral nostril (dry nostril = xeromycteria)

— trauma, otitis interna, neoplasic, idiopathic

Question 12

Treatment for neurogenic KCS?

Answer 12

Pilocarpine. — simulate PSNS

Can be oral or topical

Question 13

What virus causes destruction of lacrimal glandular epithelium leading to KCS?

Answer 13

Canine distemper

Young dogs without proper vaccination (acute and severe)

Question 14

What surgical therapy is used to treat KCS?

Answer 14

Parotid duct transposition
— when medical therapy fails

— parotid salivary duct is moved to lower conjunctival fornix and saliva replaces tears (must feed small and frequent meals)

Question 15

What are disadvantages of parotid duct transposition?

Answer 15

Reaction to higher pH of tears

Moist pyoderma from overproduction

Mineral deposition in cornea and eyelids

Question 16

What produces the lipid layer of the tear film which is important to stabilize the aqueous layer and prevent evaporation?

Answer 16

Meibomian glands

Question 17

If you have clinical signs associated with keratoconjunctivitis but a normal shimmer tear test, what is this likely caused by?

Answer 17

Qualitative keratoconjunctivitis sicca

Check meibomian glands
Or disorders of mucin layer (goblet cells)

Question 18

What clinical signs can be associated with qualitative keratoconjunctivitis sicca?

Answer 18

All KCS — blepharospasm, epiphora, hyperemia, superficial conjunctivitis, and keratitis

Corneal fibrosis — disorganized epithelium and storm create a whitish hazy appearance

Question 19

What is the tear film breakup time test?

Answer 19

The time it takes fluorescin stain to break up on the ocular surface

Normal = 20sec

Abnormal <20sec indicated mucin deficiency

Question 20

Treatment of qualitiative KCS?

Answer 20

Replace tears — lubricate with artificial tears

Reduce inflammation and stimulate tear production — immunomodulation

Question 21

What do you call an overflow of tears on the face?

Answer 21

Epiphora

Question 22

Causes of epiphora?

Answer 22

Poor drainage
— imperforate or hypoplastic puncta
— entropion

Blockage
—foreign body
— inflammation
— neoplasia

Question 23

Diagnostics for epiphora?

Answer 23

Jones test — flurorescin stain in eye, observe in nostril (+ means patency)

Flushing of NL duct
-inert catheter into puncta and look for flow from opposite puncta, then occlude puncta and look for flow out nostril

Question 24

What breeds do you see imperforate punctum? What is the treatment?

Answer 24

Cocker spaniel
Golden
Miniature poodle

Surgical resection and temporary placement of stent with topical antibiotics