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Ophtho > Conjunctiva and Lacrimal System > Flashcards

Conjunctiva and Lacrimal System Flashcards

1
Q

Conjunctiva basics

A 
Analogous to a mucous membrane
Non-keratinized stratified columnar cells
Richly vascularized
May be pigmented
3 regions
- Bulbar (on globe)
- Palpebral (on eyelid)
- Fornix (cul-de-sac)
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2
Q

Conjunctival physiology

A

Produce mucous component of tear film (goblet cells- mucin)
Provide a smooth, lubricated surface for eyelids to contact cornea
Disperse tear film
Remove debris from ocular surface
Protective/immunologic fxn (lymphoid follicles, IgA production)
Epithelium is continuous with cornea
Has normal population of bacteria
- Gr+
Few Gr -
- Interpret cultures with caution

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3
Q

Conjunctival uses

A

Easy to examine mucous membrane
Can give clues about pt systemic health
Look for petechiae, icterus, hemorrhage, palor

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4
Q

Conjunctivitis basics

A 
Inflammation of conjunctiva
Very non-specific response
Variable CS
Tx varies with cause
Common in all species
Cause varies by species
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5
Q

Common viral causes of conjunctivitis

A

FHV-1
Canine distemper
Canine herpesvirus

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6
Q

Bacterial causes of conjunctivitis

A

Uncommon in dogs and cats!
Secondary to KCS
Chlamydia in sheep, cats
Mycoplasma in goats

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7
Q

Parasitic causes of conjunctivitis

A 
Thelazia
Onchocerca
Habronema
Hepatozoon
Leishmania
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8
Q

Common non-infectious causes of conjunctivitis

A

Immune mediated (KCS in dogs)
Allergic/environmental
- Follicular conjunctivitis
Always look for primary cause

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9
Q

FHV-1

A 
Common cause of conjunctivitis in cats
Wide spectrum of CS
More common in young, stressed cats
Tx:
Reduce stress
Cidofovir .5% sol'n BID or
Famciclovir 40mg/kg TID or 90mg/kg BID
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10
Q

Allergic conjunctivitis

A

Follicular conjunctivitis
Chronic allergic stimulation
More common in dogs (very rare in cats)
May have concurrent skin allergies/atopy
May be seasonal
Conjunctival follicles (including conjunctiva of third eyelid)
Epiphora or mucoid ocular discharge
Dx of exclusion (cytology/biopsy: hyperplastic lymphoid tissue)
Tx: topical anti-histamines or anti-inflammatories

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11
Q

Diagnostic techniques

A 
Complete ophthalmic examination
Schirmer tear test
Cytology
Biopsy
C&S
Vital stains
- Fluorescein - conjunctival ulcers/erosions
- Rose Bengal - mucin deficiency
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12
Q

Conjunctivitis Tx

A 
Depends on etiology
- Targeted therapy
 . tear stimulants if KCS
 . Antiviral tx if herpes
 . Systemic tx if OMSD
- Anti-inflammatories
- Abx
- Lubricants
- Eye wash - NOT contact lens sol'n
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13
Q

Conjunctival neoplasia basics

A 
Usually primary
Often malignant
FNA or biopsy to Dx
Many amenable to local excision and adjunctive therapy (cryoablation, chemotherapy, hyperthermia)
Enucleation may be required
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14
Q

Non neoplastic conjunctival masses

A

Dermoid
Inflammatory (nodular granulomatous episcleritis)
Parasitic granuloma (onchocerca)
Retrobulbar fat prolapse

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15
Q

Dermoid

A

Normal tissue, abnormal location

Tx: Sx

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16
Q

Traumatic abnormalities

A 
Chemosis, hyperemia, lacerations, hemorrhage
Lacerations rarely need suturing
Hemorrhage
- Blunt trauma
- Proptosis
- Strangulation
- Coagulopathy
17
Q

Nasolacrimal apparatus

A 
Secretory components
- Orbital lacrimal gland
- Gland of TE
Drainage system for tears
- Upper and lower eyelid puncta (medial canthus) enter short canaliculi
- Connect at lacrimal sac
- NL duct opens in nasal vestibule
18
Q

Drainage system

A

Puncta to canaliculus to lacrimal sac to nasolacrimal duct to nasal puncta

19
Q

Tear film

A

3 layers
- Outer lipid layer - meibomian glands
- Middle layer - lacrimal glands
- Inner mucin layer - goblet cells, epithelial cells
Lubricate, cleanse, and protect globe
Surface health depends on both sufficient quantity and stability

20
Q

7 fxn of tear film

A

Smooth ocular surface for refraction of light
Lubrication of the ocular surface and eyelids
Provide oxygen and nutrients to the corneal surface
Give WBC access to cornea and conjunctiva
Remove debris and foreign material from ocular surface
Defend ocular surface from pathogens

21
Q

Keratoconjunctivitis sicca

A 
Most common form: quantitative
- Deficiency of aqueous layer
- dogs most frequently affected
Less common form: qualitative
- Deficiency of mucus or lipid layers
- Harder to Dx
- Treat with HAbased drop or gel
22
Q

Causes of KCS

A 
Immune-mediated: #1 cause (T cell mediated destruction of lacrimal tissue)
Metabolic disease (DM)
Drug induced (sulfas, Etodolac NSAID, Atropine temporary)
Infectious: CDV
Congenital hypoplasia/aplasia of lacrimal gland
Anesthesia/sedation
Neurogenic (CNVII)
Vitamin A deficiency
Loss of CN V afferent fxn
Radiation
Trauma
Iatrogenic
23
Q

KCS predisposed breeds

A

English bulldogs, WHWT, Lhasa Apso

24
Q

CS of KCS

A 
Mucoid, ropy, tenacious discharge
Conjunctival hyperemia/conjunctivitis
Corneal vascularization
Corneal pigmentation
Corneal fibrosis
Corneal ulceration
Lackluster corneal surface
Blepharitis
Loss of vision
25
Q

Schirmer tear test

A

Quantitative assessment of tear fluid
Normal 15-25mm/min
Quantitative tear deficiency = KCS
Perform in all cases of conjunctivitis

26
Q

Tear film breakup time

A 
Indication of tear stability
Fluorescein applied
Lids blink, then hold open
Tear film is observed under cobalt-blue light and the time between the last blink and appearance of the first break in tear film is recorded
<10sec abnormal
27
Q

Medical Tx of KCS

A

Lacrimostimulants

  • Cyclosporine A or Tacrolimus
  • Inhibit T cells from infiltrating and destroying lacrimal gland
  • 2-3 mo to reach efficacy

Tear replacement

  • Gel or ointment preferable - longer lasting
  • More frequent admin until tear stimulant has reached efficacy
28
Q

Cyclosporine

A

Increases tear production in 80% of cases
Has T helper cell inhibitory activity
Reduces pigmentary keratitis
Treat for 4-8 wk before considering treatment failure
Alternative related drugs: tacrolimus, Pimecrolimus

29
Q

Potential complications of a parotid duct transposition

A

Excessive tear flow and facial dermatitis
Ca precipitates can deposit on the cornea creating a keratopathy
Sialoliths can also cause blockage and necessitate Sx repair

Ophtho (5 decks)

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