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VMCVM Ophthalmology > Lacrimal/Nasolacrimal system > Flashcards

Lacrimal/Nasolacrimal system Flashcards

1
Q

3 Tear film layers and where they each come from

A
  1. Oily layer Meibomian Gland
  2. Watery portion - lacrimal gland and gland of 3rd eyelid
  3. Mucus - bulbar, paperbral and 3rd eyelid conjunctiva
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2
Q

4 functions of precorneal tear film

A
  1. antimicrobial activity
  2. optical clarity
  3. oxygen transport
  4. waste removal
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3
Q

Nerves involved in tearing

A

afferent ophthalmic branch of CN5, efferent psns fibers of CN7

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4
Q

Nasolacrimal ducts and punctae dog

A

upper and lower palpebral punctae, passes through lacrimal and maxillary bones, exits in the nasal vestibule, lateral to the floor of the vestibule

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5
Q

Nasolacrimal ducts and punctae cat

A

same as dog

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6
Q

Nasolacrimal ducts and punctae horses

A

palpebral punctum similar to dogs, can visualize the nasal punctum in the floor of the nasal vestibule, medially

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7
Q

Nasolacrimal ducts and punctae cattle and llama

A

similar to the horse with the exception that the nasal punctae are more dorsally and laterally located than in the horse

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8
Q

Keratoconjunctivitis sicca, what is it?

A

Decreased tear film, Dry Eyes.
the MOST important nasolacrimal system disorder. It is sight threatening and PAINFUL.
DOGs>cats>others

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9
Q

Clinical signs of KCS in Dog

A
  1. Decreased aqueous tear film as measured with a Schirmer tear test (STT) strip
  2. PAIN
  3. Thick mucous thread, dried ocular discharge around lids due to lack of aqueous tear
  4. Corneal and conjunctival changes (dry, reddened, ulcers, neovascularization, pigmentation
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10
Q

Clinical signs of KCS in Cat

A

Schirmer tear test does not work well in cats

cats show little signs like mucus, mild keratitis, repeated bouts of conjunctivitis

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11
Q

Breed Predispositions

A

Brachycephalics: Pugs, Lhasa Apsos, Shih Tzus, Boston Terriers, and English Bulldogs
small terriers such as Cairns and West Highland White
Shelties, Poodles, Golden Retrievers, Spaniels (American, English, Cavalier
Any breed predisposed to atopic dermatitis (above)

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12
Q

Cause of KCS in Dog

A 
#1 Immune-mediated/Idiopathic
Congenital
Active infections, Previous infections
CN7 damage (Cocker Spaniels)
Sulfonamides and etodoloc and Loco weed poisoning in cattle out west
Atropine
General anesthesia (why we put lube)
Iatrogenic (3rd eyelid removal or post-radiation)
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13
Q

Medical therapy of KCS

A

Medical therapy can induce natural tear production

  1. Cyclosporine-A – works well in predisposed dogs, not in other species (cats). Does not work in drug induced KCS. Tacrolimus also works (other calcineurin inhibitor/T-cell suppressor)
  2. Supportive care - artificial tears
  3. Abx if indicated
  4. Mucolytic agents - acetylcysteine
  5. lacrimomimetics - Pilocarpine
  6. Corticosteroids - dec. surface inflam. but more prone to infections
  7. Good hygiene
  8. Oral interferon
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14
Q

Surgical Therapy of KCS

A
  1. Temporary - tarsorrhaphy or 3rd eyelid flap
  2. Permanent - tarsorrhaphy, medial or lateral
  3. Parotid duct transposition for “Last Ditch Effort” when months of medical therapy don’t work but lots of potential complications
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15
Q

What is Epiphora?

A

Epiphora is abnormal flow of tears onto the face. Compared to decreased tear production, this is not near as big a problem to the animal.

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16
Q

Causes of epiphora

A
  1. Hypersecretion (infections, irritations, FBs)

2. Poor drainage (congenital, entropion, ectropion, deformities, nasolacrimal obstruction

17
Q

Diagnosis of epiphora

A
  1. Schirmer Tear test, compare eye to normals and eye to eye
  2. Fluorescein, see if it comes out nose
  3. Flush nasolacrimal duct
  4. contrast rads
  5. Poodle epiphora – Poodles, Bichon, Maltese, Cocker Spaniels
18
Q

Medical therapy of epiphora

A
  1. Flush nasolacrimal ducts then give anti-inflammatory steroid drop
  2. Treat conjunctivitis or other surface disease
  3. Oral tetracycline to reduce pigmentation
19
Q

Surgical therapy of epiphora

A
  1. if atresia, can open it with suture and pigtail probe
  2. repeatedly plugged ducts, stent a few weeks
  3. perm. scarred shut then dacryocystorhinostomy
  4. DO NOT REMOVE 3rd EYELID!
20
Q

What is Dacryocystitis?

A

Infection or inflammation of the nasolacrimal duct system

21
Q

Clinical signs of dacryocystitis

A

Epiphora PLUS Purulent discharge. May or may not be painful

22
Q

Causes of dacryocystitis

A
  1. congenital atresia (common in horses and llamas)
  2. FB obstruction
  3. compression due to facial fracture
23
Q

Therapy of dacryocystitis

A
  1. Frequent flushing w/ systemic and topical abx
  2. duct catheterization for 2-3 weeks with topical abx/corticosteroid drops
  3. Open congenital malformation (horses and llamas)

VMCVM Ophthalmology (7 decks)

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