Lacrimal System Flashcards

1
Q

Which structure secretes the majority of the tear film?

A

Lacrimal gland.

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2
Q

Which system facilitates the drainage of tears?

A

Nasolacrimal system.

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3
Q

Describe the tear flow pathway.

A
  1. Secretion by lacrimal gland onto ocular surface.
  2. Channeled medially by orbicularis pump mechanism.
  3. Drainage into nasolacrimal system via the upper and lower puncta.
  4. Flow through the upper and lower canaliculi into the common canaliculus.
  5. Common canaliculus -> nasolacrimal sac -> nasolacrimal duct -> inferior nasal meatus.
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4
Q

Which imbalance causes disorders of tearing?

A

Imbalance between secretion and excretion of tears.

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5
Q

How many layers are in the tear film?

A

3 layers.

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6
Q

What are the 3 layers of the tear film?

A
  1. Mucin layer - deepest.
  2. Aqueous layer - thickest layer.
  3. Lipid layer - most superficial and thinnest layer.
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7
Q

What produces the mucin layer (tear film)?

A

Conjunctival goblet cells.

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8
Q

What is the function of the mucin layer (tear film)?

A
  • Spreads the film evenly.
  • Maintains stability on ocular surface.
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9
Q

What produces the aqueous layer (tear film)?

A

Lacrimal gland.

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10
Q

What is the function of the aqueous layer (tear film)?

A

Immune function.

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11
Q

What produces the lipid layer (tear film)?

A

Meibomian gland (sebaceous).

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12
Q

What is the function of the lipid layer (tear film)?

A

Prevents evaporation of the tear film.

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13
Q

Which is the thinnest layer of the tear film?

A

Lipid layer.

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14
Q

Which is the thickest layer of the tear film?

A

Aqueous layer.

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15
Q

What is reflex tearing?

A
  • Common cause of hypersecretion.
  • Caused by irritation of the ocular surface.
  • A good quality tear film reduces reflex tearing.
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16
Q

What are the two types of lacrimal gland?

A
  • Main.
  • Accessory.
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17
Q

Which nerve provides afferent sensory innervation to the lacrimal gland?

A

CN5 -> CNV1 -> lacrimal nerve.

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18
Q

Which nerve innervates the secretomotor aspect of lacrimation?

A

CN7 (parasympathetic).

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19
Q

What are the two types of accessory lacrimal gland?

A
  • Krause.
  • Wolfring.
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20
Q

What is the function of the accessory lacrimal glands?

A

Maintain a basal aqueous layer.

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21
Q

Where are Krause glands found?

A
  • Conjunctival fornices.
  • More abundant in the upper fornix.
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22
Q

Where are Wolfring glands found?

A
  • Tarsal plate.
  • Less numerous but bigger.
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23
Q

Which accessory lacrimal gland is bigger?

A

Wolfring.

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24
Q

Which accessory lacrimal gland is more abundant?

A

Krause.

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25
Q

Which glands produce the mucin layer of the tear film?

A

Glands of Moll and Zeis.

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26
Q

What are Moll glands?

A
  • Modified sweat glands.
  • Apocrine.
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27
Q

What are Zeis glands?

A
  • Sebaceous glands.
  • Holocrine.
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28
Q

What type of gland are Meibomian glands?

A

Holocrine.

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29
Q

Describe Schirmer’s test.

A

Filter paper placed under lower lid and amount of moisture is measured after 5 mins.

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30
Q

Describe the interpretation of Schirmer’s test.

A
  • > 10mm is normal.
  • <5mm is tear deficiency.
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31
Q

Describe the tear film break-up time.

A

Eye is stained with fluorescein dye and the time taken for the first dry spot to appear on the cornea is measured.

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32
Q

Describe the interpretation of the tear film break-up test.

A
  • <5 seconds - abnormal tear film.
  • 10-30 seconds - normal.
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33
Q

Describe the Jones 1 test.

A

Dye is squirted onto the conjunctiva and cotton bud is placed in the inferior meatus.

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34
Q

Describe the interpretation of the Jones 1 test.

A
  • If dye on cotton bud - normal.
  • If no dye on cotton bud - do Jones 2.
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35
Q

Describe the Jones 2 test.

A

Dye syringed into the nasolacrimal system and cotton bud placed in the inferior meatus.

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36
Q

Describe the interpretation of the Jones 2 test.

A
  • No dye on cotton bud - nasolacrimal system obstruction.
  • Dye is now seen on cotton bud - pump/punctal problem.
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37
Q

What is dacryocystography?

A

Radiological evaluation using injected fluorescent contrast to evaluate the nasolacrimal system morphology.

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38
Q

What are the pros and cons of dacryocystography?

A

Pro:
- Excellent anatomical detail for evaluation.

Con:
- Invasive and painful.

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39
Q

What is dacryoscintigraphy?

A

Radiological evaluation of nasolacrimal system drainage using radiopharmaceutical eyedrops.

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40
Q

What are the pros and cons of dacryoscintigraphy?

A

Pro:
- Painless.

Con:
- Evaluation of tear flow but provides poor anatomical detail.

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41
Q

What is the pathology of dry eye?

A
  • Caused by a problem in the tear film (hyposecretion/instability) or increased evaporation.
42
Q

What is the consequence of dry eye?

A

Erosions of the ocular surface leading to blindness.

43
Q

Who is most likely to present with dry eye?

A
  • Elderly people.
  • Women of post-menopausal age.
44
Q

Describe the presentation of dry eye.

A

Gritty, irritated, red eyes.

45
Q

What are the investigations used for dry eye?

A
  • Schirmer’s test (<5mm).
  • Tear film breakup time (<5 seconds).
  • Ocular surface staining (fluorescein, rose bengal, lissamine green).
46
Q

Describe the treatment for dry eye according to the treatment ladder.

A
  1. Lubrication and artificial tears.
  2. Topical steroids + pilocarpine.
  3. Punctal plugs.
  4. Autologous serum drops.
  5. Bandage contact lenses.
  6. Tarsorrhaphy - temporary measure of sewing the eyelids shut.
47
Q

What is Sjogren’s?

A

Autoimmune destruction of the salivary and lacrimal glands.

48
Q

Which conditions are associated with Sjogren’s?

A
  • Rheumatoid arthritis.
  • SLE.

Although it can occur as a primary disease.

49
Q

Describe the presentation of Sjogren’s.

A
  • Triad - dry eyes, dry mouth, parotid gland swelling.
  • Gritty, burning eyes.
50
Q

Which auto-antibodies would be positive for Sjogren’s?

A

Anti-Ro and anti-La.

51
Q

Which dye is used to see erosions on the cornea?

A

Fluorescein.

52
Q

Which dye is used to see erosions on the conjunctiva?

A

Lissamine green.

53
Q

What is the management of Sjogren’s?

A

Stepwise treatment:
1. Lubrication + artificial tears.
2. Topical steroids + pilocarpine.
3. Punctal plugs.
4. Autologous serum drops.
5. Bandage contact lenses.
6. Tarsorrhaphy (temporary sewing shut of the eyelids).

54
Q

What is xerophthalmia?

A

Major cause of childhood blindness in Africa.

55
Q

Describe the pathology of xerophthalmia.

A

Severe vitamin A deficiency > lack of tear production > dry eyes.

56
Q

Describe the presentation of xerophthalmia.

A

Characteristic Bitot’s spots - triangular conjunctival keratin buildup.

57
Q

What are Bitot’s spots?

A

Triangular conjunctival keratin buildup - found in xerophthalmia.

58
Q

What are the investigations for xerophthalmia?

A
  • Tear film break up time <5 seconds.
  • Schirmer’s test positive.
  • Ocular surface staining.
59
Q

Describe the management of xerophthalmia.

A

Stepwise treatment:
1. Lubrication + artificial tears.
2. Topical steroids + pilocarpine.
3. Punctal plugs.
4. Autologous serum drops.
5. Bandage contact lenses.
6. Tarsorrhaphy - temporary sewing shut of the eyelids.

60
Q

What is epiphora?

A

Watery eyes.

61
Q

What are the 2 mechanisms of epiphora?

A
  • Nasolacrimal drainage failure.
  • Hypersecretion.
62
Q

What are the 3 main causes of epiphora?

A
  • Obstruction of the nasolacrimal system.
  • Orbicularis pump failure.
  • Hypersecretion.
63
Q

What are the causes of nasolacrimal system obstruction?

A
  • Punctal eversion.
  • Canalicular fibrosis.
  • Lacrimal sac obstruction.
  • Nasolacrimal duct obstruction.
64
Q

What are the causes of orbicularis pump failure?

A
  • Lid laxity.
  • CN7 palsy.
  • Lateral dermatochalasis.
  • Overzealous punctoplasty.
65
Q

What are the causes of hypersecretion?

A
  • Irritation - foreign body or lashes (trichiasis) or entropion.
  • Autonomic abnormalities and pro-secretory drugs (pilocarpine).
66
Q

Describe the management of hypersecretion.

A

Lubricants and other drops to manage irritation.

67
Q

What is congenital nasolacrimal duct obstruction?

A

Classic cause of infant epiphora.

68
Q

Describe the pathology of congenital nasolacrimal duct obstruction.

A

Imperforate membrane over the valve of Hasner (between the nasolacrimal duct and inferior nasal meatus).

69
Q

Describe the presentation of congenital nasolacrimal duct obstruction.

A
  • Infant.
  • Epiphora.
  • Discharge when the lacrimal sac is squeezed.
70
Q

Describe the management of congenital nasolacrimal system obstruction.

A

<12 months of age:
- Massage + topical antibiotics + observation.

> 12 months of age:
1. Syringing and probing.
2. Silicone stent intubation.
3. Dacryocystorhinostomy (DCR).

N.B., if the blockage is severe enough to negate the passage of a probe, intubation will prove difficult and DCR might have to be attempted instead.

71
Q

What are the causes of acquired lacrimal system obstruction?

A
  • Punctal stenosis.
  • Punctal eversion.
  • Orbicularis pump failure.
  • Dermatochalasis/lateral wicking.
  • Nasolacrimal duct obstruction.
  • Canalicular obstruction.
72
Q

What is the treatment for punctal stenosis?

A

Punctoplasty.

73
Q

What is the treatment for punctal eversion?

A

Cautery.

74
Q

What is the treatment for orbicularis pump failure?

A

Lower lid tightening with lateral tarsal strip.

75
Q

What is the treatment for dermatochalasis/lateral wicking?

A

Upper lid blepharoplasty.

76
Q

What is the treatment for nasolacrimal duct obstruction?

A

Dacryocystorhinostomy (DCR) (bypass nasolacrimal duct and drain to middle nasal meatus) ± intubation.

77
Q

What is the first-line treatment for canalicular obstruction?

A

DCR with retrograde intubation.

78
Q

What is the second-line treatment for canalicular obstruction?

A

Lester Jones tube.

79
Q

Which group of people is dermatochalasis seen in?

A
  • Elderly.
  • Obese.
80
Q

Which group of people is orbicularis pump failure seen in?

A

Neuropathies - e.g., Bell’s palsy.

81
Q

What is dacryoadenitis.

A

Inflammation of the lacrimal glands.

82
Q

Describe the pathology of dacryoadenitis.

A
  • Often idiopathic.
  • Secondary causes - viral infection, e.g., mumps.
83
Q

Describe the presentation of dacryoadenitis.

A
  • Acutely painful upper LATERAL lid.
  • Swollen lacrimal gland.
  • Hypoglobus (medially) - eyeball abnormally lowered in eye socket.
  • Enophthalmos.
  • S-shaped eyelid deformity.
84
Q

Describe the investigations for dacryoadenitis. When are they done?

A
  • Orbital MRI/CT.
  • Biopsy.

Only done if recurrent or suspicious.

85
Q

What should bilateral dacryoadenitis raise suspicion of?

A

Sarcoidosis.

86
Q

Describe the management of dacryoadenitis.

A

Oral NSAIDs or steroids.

87
Q

How long does dacryoadenitis take to resolve?

A

Months.

88
Q

What is canaliculitis?

A

Inflammation of the canaliculi.

89
Q

Describe the pathology of canaliculitis.

A
  • Often caused by infection.
  • Most commonly by Actinomyces.
90
Q

Describe the presentation of canaliculitis.

A

Unilateral epiphora and discharge.

91
Q

Describe the management of canaliculitis.

A

Topical antibiotics and canaliculotomy.

92
Q

How is canalicular repair done following a canalicular trauma?

A

With a Mini Monoka tube for 3 months.

93
Q

What is dacryocystitis?

A

Inflammation of the lacrimal sac.

94
Q

Why does dacryocystitis need to be managed urgently?

A

To prevent the spread of cellulitis.

95
Q

Describe the pathology of dacryocystitis.

A
  • Nasolacrimal duct obstruction.
96
Q

Which species causes dacryocystitis?

A

Staphylococcus.

97
Q

Describe the presentation of dacryocystitis.

A

Acutely with epiphora and tender lacrimal sac.

98
Q

Describe the management of acute dacryocystitis.

A

Warm compresses and oral antibiotics.

99
Q

Describe the management of chronic/recurrent dacryocystitis.

A

Dacryocystorhinostomy.

100
Q

What is dacryocystorhinostomy (DCR)?

A

Opens connection between the nasolacrimal duct and middle nasal meatus.