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Ocular Physiology > Lacrimal Gland > Flashcards

Lacrimal Gland Flashcards

1
Q

What kind of gland is the lacrimal gland

A

Exocrine gland (like the mammary and salivary gland)

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2
Q

Myoepithelial creates

A

Force for excretion of tears

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3
Q

Lacrimal gland develops from multiple

A

Ectoderm buds at anterior superolateral orbit

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4
Q

Lacrimal glands may not function fully for up to

A

6 weeks after birth

Might explain why newborn dont produce tears when crying

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5
Q

When someone has extreme dry eye

A

Scar tissue will form over the cornea.

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6
Q

Why dont artificial tears work too well

A

No growth factors

So there is nothing to stimulate the the epithelium to grow so it doesn’t help it heal

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7
Q

During sleep, secretion of all major proteins and water

A

Is inhibited

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8
Q

Total removal of the main lacrimal gland

A

Does not in itself lead to dry eye

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9
Q

Removal of parasympathetic innervation to the lacrimal gland

A

Leads to rapid reduction in tear flow

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10
Q

sensory input for cornea

A

CNV

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11
Q

In healthy individuals, everyday ocular surface stimulation like mechanical irritation, low humidity, excess wind and CLs triggers

A

Neural signal that initiates reflex tear secretion (CNV)from the main and accessory lacrimal glands

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12
Q

Tear reflex corneal nerves

A

CNV in

CNVII out

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13
Q

Inflammation interrupts normal homeostasis and leading to

A

Ocular surface disease and dry eye involving Cytokines secretion which disrupts neural arc

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14
Q

Basal aqueous secretion decreases with

A

Age and during sleep

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15
Q

What causes aqueous secretion?

A

CNV (most common)

  • dazzle (IIN)
  • taste (VIIN)
  • cough/sneeze /laugh (IXN, XN)
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16
Q

True tear allergan

A

Irritates nasal mucosa to stimulate tear production

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17
Q

Loss of water from the tear film leads to increased osmolarity and tears become more

A

Concentrated

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18
Q

When evaporation increases (tonicity)

A

Tonicity increases

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19
Q

When flow rate increases (tonicity)

A

Decreases

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20
Q

When flow rate decreases

A

Tonicity increases

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21
Q

When tonicity increases. Water is

A

Drawn from the cornea and the cells dry - irritating the eye

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22
Q

Low tonicity leads to

A

Corneal edema

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23
Q

High tonicity leads to

A

Corneal dehydration

24
Q

Diurnal rhythm in lacrimal secretion

A

NONE

25
Q

Tear production is stimulated by ___ agents. And decreased by _____agents.

A

Stimulated by cholinergic (policarpine)

Decreases by anto cholinergic (antihistamines)

26
Q

Newborns secrete tears in the first

A

24 hrs

27
Q

Hypotonic tears result from

A

Increased stimulation (more fluid & less dissolved protein)

28
Q

Hypertonic tears result from

A

Decreased stimulation

Evaporation (increase concentration by 10-20%)

29
Q

Hypersecretion of tears occur from

A

Irritation (CNV)

Foreign body, trauma, disease of cornea/conjunctiva of eyelid, nasal mucosa

30
Q

Hyposecretion of tears occur from

A

SJORGENS SYNDROME
Inflammatory disease of salivary and lacrimal gland
Scarring due to infection

31
Q

Typical tonicity range of tears

A

304-318 moms/L

32
Q

Osmolarity changes in CL wearers

A

Osmolarity decreases (tearing) initially then increases with adaptation

33
Q

Osmolarity of dry eye

A

Higher than 318 mosm/L

34
Q

Cornea temperature

A

Lower than the rest of the body (35-36 degrees celcius)

35
Q

Inflammatory enlargement of lacrimal gland

A

Dacryoadenitis

Unilateral, infection of some sort

36
Q

Approximately 50% of all lacrimal gland masses are

A

Inflammatory, other half are neoplasms

37
Q

The proper position of the eyelids against the globe and the position of the puncta to the tear lake are important for

A

Capillary attraction to draw the tears into the canaliculi

38
Q

If lids fold out , the tears wont touch the ocular surface and

A

Wont be able to drain (capillary attraction)

39
Q

Tears are removed by ____ attraction due to the vacuum formed in the lacrimal sac. This is influenced by ___ which creates the pressure.

A

Capillary

Orbicularis muscle

40
Q

The amount of tears present on the ocular surface at any given time is a function of both

A

Secretion of components that make up the tears and the drainage and evaporation of tears

41
Q

Drainage is via

A

Punctures -> canaliculi -lacrimal sac-> nasolacrimal duct to the valve of Hansel to nose

42
Q

Tears move into the puncta due to

A

Capillary attraction

43
Q

A sticky, watery eye with positive regurgitation on pressure over the lacrimal sac conforms the diagnosis

A

Epiphora
Common in children
Usually resolves on its own

44
Q

Nasolacrimal duct obstruction can cause

A

Tearing(epiphora) , crusting of eyelids, and lower lid erythema

45
Q

Nasolacrimal duct obstruction can occur due to

A

Chronic sinus disease, involutional stenosis, dacryocystitis or nasoorbital trauma

46
Q

Epiphora IN CILDREN can be caused by

A

Obstruction of nasolacrimal passage or NON OBSTRUCTIVE factors such as EYELID MALPOSITION, pump insufficiency , tear film instability, or hypersecretin

47
Q

Epiphora in adults is caused by

A

Disturbed ocular surface tear flow such as lid malpositon (dry eye, blepharitis, TRICHIASIS)
ECTROPION

48
Q

In adults most common cause of epiphora is

A

Nasolacrimal duct obstruction

49
Q

Most common cause of inflammation of the canaliculus

A

Gram positive rod

50
Q

Severe dacrocytis can

A

Break through the skin

51
Q

Acute dacryocystitis is

A

Inflammation of the punctum

May have a fever - tells you there is in infection

52
Q

Disorders of the tear drainage can be caused by (2)

A

Irritation of ocular surface or occlusion of any part of the drainage system

53
Q

Lower cannaliculus drains 60% of the tear layer due to

A

Gravity

54
Q

Irrigation of the lower lacrimal system under topical anesthetia shows

A

How much drains

55
Q

Dacryocystitis

A

Obstruction of nasolacrimal duct

Ocular Physiology (7 decks)

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