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Ophthalmology Rotation > Lacrimal System and Nictitating Membrane > Flashcards

Lacrimal System and Nictitating Membrane Flashcards

1
Q

Pre-corneal Tear Film

A
  • Crucial for ocular surface health
  • Numerous functions
    – Lubrication between lids and ocular surface
    – Aids corneal refraction
    – Antimicrobial properties
    – Primary corneal oxygen source
    – Removal of debris through tear drainage
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2
Q

Trilaminar Tear Film

  • layers
A
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3
Q

Aqueous Tear Production

A
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4
Q

Tear Film Drainage

A
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5
Q

lacrimal system and nictitating membrane (meekins)

Tear Film Deficiency

A
  • *Quantitative = KCS
    – Keratoconjunctivitis sicca
    – Decreased aqueous tear production
  • Qualitative
    – Disorder of mucin or lipid tear components
    – Causes tear film instability
  • Result in desiccation and inflammation of the ocular surface
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6
Q

lacrimal system and nictitating membrane (meekins)

Keratoconjunctivitis Sicca (KCS)

  • what
  • who
A
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7
Q

lacrimal system and nictitating membrane (meekins)

Keratoconjunctivitis Sicca (KCS)

  • Clinical Signs
A
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8
Q

lacrimal system and nictitating membrane (meekins)

KCS Causes

A
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9
Q

lacrimal system and nictitating membrane (meekins)

KCS Causes
• Neurologic dysfunction

A
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10
Q

lacrimal system and nictitating membrane (meekins)

Diagnosis of KCS

A
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11
Q

lacrimal system and nictitating membrane (meekins)

Summary: Treatment of KCS

A
  • Tear stimulation – lacrimostimulants
  • Tear replacement – lacrimomimetics
  • +/- supplemental therapy
    – Secondary bacterial infections
  • Client education
    – Must use medications as often as directed
    – May take a month or more to see STT improvement
    – Tear stimulant therapy is lifelong!
  • Parotid duct transposition surgery option
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12
Q

lacrimal system and nictitating membrane (meekins)

Lacrimostimulants

A
  • Cyclosporine A
    • Optimmune® 0.2% ointment
    • Compounded 1% or 2% drops or ointment
  • Tacrolimus
    • Compounded 0.02% or 0.03% formulations
    • 10-100 times more potent than CsA in vitro
  • T cell inhibitors with anti-inflammatory, anti-pigment, and possibly anti-fibrotic effects
  • Use BID for life!
  • Reputable compounding pharmacy is important
  • Cholinergic agent (Pilocarpine)
    • Indicated in cases of neurogenic KCS resulting from parasympathetic denervation
    • Dilute topical (0.125%, compounded) or very careful oral dosing
      • Warn owners of side effects!
        • Salivation
        • Lacrimation (desired!)
        • Urination
        • Defecation
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13
Q

lacrimal system and nictitating membrane (meekins)

Lacrimomimetics

A

• Tear replacements or substitutes
• Many OTC products
– Choose one with increased viscosity (not ‘rewetting drops’)
• Use 4-6 times daily+
– While tear production is decreased
– Ointments can be used before bedtime

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14
Q

Ocular Cleansing

A
  • Frequently remove discharge
    • OTC eyewash/saline
    • Minimizes debris accumulation
    • Important before lacrimostimulant application
      • Ensure drug contacts ocular surface tissues
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15
Q

Antibacterial Medications

A
  • Used for secondary bacterial infections or concurrent corneal ulcers (to prevent infection)
  • Broad-spectrum topical antibiotic
    – Triple antibiotic ophthalmic ointment preferred (NeoPolyBac)
    – TID to QID for 2-3 weeks
  • Bacterial culture and sensitivity testing is warranted if purulent discharge persists
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16
Q

lacrimal system and nictitating membrane (meekins)

Surgical Treatment
• Parotid duct transposition (PDT)

A
  • Saliva is used to lubricate the cornea in place of tears
  • Recommended if medical therapy fails
    • Must give adequate time for medical therapy response
  • Frequent small meals fed post-op to stimulate salivation
  • Complications possible
    • Mineral deposition
    • Moist dermatitis
    • Sialolith/sialocele
  • Most still need medications post-op
17
Q

lacrimal system and nictitating membrane (meekins)

Qualitative Tear Deficiency

  • what
  • clinical signs
A
  • Abnormality in mucin or lipid layer of tear film
  • Clinical signs
    • Conjunctival hyperemia and dull appearance to the corneal surface
    • Keratitis consisting of variable pigmentation, edema, multifocal areas of fluorescein stippling or erosions
      • With normal STT
    • Marginal blepharitis, meibomianitis, chalazion
      • Both cause and clinical sign
    • Corneal ulcers possible (but less likely)
    • Signs may be subtle
18
Q

lacrimal system and nictitating membrane (meekins)

Qualitative Tear Deficiency
• Diagnosis

A
  • Normal aqueous production (STT 15-25 mm/min)
  • Lipid deficiency
    • Inspect Meibomian glands/secretions
  • Mucin deficiency
    • **Tear film breakup time**
      • Apply fluorescein dye
      • Normal
        • >20 sec dogs
        • >17 sec cats
19
Q

lacrimal system and nictitating membrane (meekins)

Qualitative Tear Deficiency Treatment

  • lipid
  • mucin
A
20
Q

lacrimal system and nictitating membrane (meekins)

Nictitating Membrane

  • what
  • properties
A
21
Q

Nictitating Membrane

  • movement
  • functions
A
  • Movement
    – Passively elevates as globe moves posterior in orbit
    – Sympathetic smooth muscle fibers aid TE retraction (cats)
  • Functions
    – Production of aqueous tears
    – Distribution of pre-corneal tear film
    – Protection of the ocular surface
    – It’s there for a reason – don’t just cut it out!
22
Q

lacrimal system and nictitating membrane (meekins)

Causes: Third Eyelid Elevation

A
23
Q

lacrimal system and nictitating membrane (meekins)

Prolapsed Gland of the Third Eyelid

  • common name?
  • who?
A
24
Q

lacrimal system and nictitating membrane (meekins)

Prolapsed Gland Treatment:

A
25
Q

lacrimal system and nictitating membrane (meekins)

“Scrolled” Third Eyelid Cartilage

A
26
Q

lacrimal system and nictitating membrane (meekins)

Nictitans Neoplasia

A
27
Q

lacrimal system and nictitating membrane (meekins)

Epiphora

  • what
  • causes
A
28
Q

lacrimal system and nictitating membrane (meekins)

Epiphora Diagnostic Tests

A
29
Q

lacrimal system and nictitating membrane (meekins)

Dacryocystitis

A
  • Clinical signs
    • Mucopurulent discharge, epiphora, swelling or draining fistulas in medial canthal region
    • Typically no blepharospasm, minimal conjunctival hyperemia
  • Usually secondary to foreign bodies but rarely find them
  • Treatment: repeated NL flushing, topical antibiotic + steroid solution
    • May require surgery if FB is identified

Purulent discharge from lower lacrimal punctum

30
Q

lacrimal system and nictitating membrane (meekins)

Summary

  • KCS is the most commonly diagnosed tear film abnormality in…
  • Major third eyelid abnormalities include…
  • When epiphora is diagnosed…
  • Dacryocystitis is…
A
  • KCS is the most commonly diagnosed tear film abnormality in dogs
  • Major third eyelid abnormalities include prolapsed NM gland and scrolled cartilage
  • When epiphora is diagnosed, increased production vs. inadequate drainage must be determined
  • Dacryocystitis is an uncommon problem, generally resulting in purulent ocular discharge without blepharospasm

Ophthalmology Rotation (20 decks)

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