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Ocular Physiology > Eyelids > Flashcards

Eyelids Flashcards

1
Q

why is the skin in the eyelids fat free

A

so they are lighter for the muscles to lift for how often we blink

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2
Q

what is blepharochalsis

A

inflammation of the eyelid

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3
Q

what type of carcinoma is related to UVR exposure

A

basal cell carcinoma

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4
Q

which lids (upper or lower) are affected by benign growths

A

both have an equal change of getting them

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5
Q

which lid (upper or lower) has a greater chance of developing a malignant tumor

A

the lower lid is four times more likely to get one

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6
Q

why wouldn’t the upper lid be as common in getting malignant tumors

A

the eyebrows protect the upper lid from the sun

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7
Q

what does the levator palpebrae superioris do

A

elevates the upper lid (striated muscle)

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8
Q

what do the Muller muscle fibers do

A

modulate position of lids of the open eye

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9
Q

what marks the palpebral portion from the orbital portion of the lid

A

the insertion of the levator palpebrae superioris (superior palpebral sulcus)

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10
Q

when would someone have an absence of the superior palpebral sulcus

A

certain ethnicities will not have a distinct line or if there is ptosis (especially congenital)

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11
Q

what does the orbicularis oculi do

A

(striated voluntary muscle) closes the lids and helps hold the lid tightly against the eye, assists in spreading tears and flushing waste

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12
Q

what innervates the orbicularis oculi

A

CN 7- facial

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13
Q

what would happen if CN 7-facial of the orbicularis oculi was paralyzed

A

dry eye conditions, lagophthalmus (inability to close lids)

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14
Q

at what point does the levator palpebrae superioris become tendinous

A

as it enters the lid becoming the “aponeurosis of the levator”

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15
Q

what innervates the levator palpebrae superioris

A

CN 3 oculomotor nerve

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16
Q

what type of innervation does the tarsal muscle (Mullers muscle) superior and inferior have

A

sympathetic innervation

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17
Q

what does contraction of the tarsal muscle (mullers) do

A

aids the action of the levator

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18
Q

what would damage to the tarsal muscle do

A

damage to the sympathetic innervation causes a droopy lid (ptosis)

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19
Q

what type of tissue is in the submuscular areolar tissue

A

loose connective tissue between the muscle and tarsal plate (fat free)

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20
Q

what is in the fibrous layer of the eyelid

A

dense fibrous tissue and collagen that gives firmness and shape to lids (tarsal plate); more developed collagen in the upper lid

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21
Q

what is floppy eyelid syndrome

A

the upper lids are flaccid and easily everted

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22
Q

what causes floppy eyelid syndrome

A

decreased tarsal elastin and genetic abnormalities of collagen and elastin

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23
Q

what are the symptoms of floppy eyelid syndrome

A

burning and irritation, contact between eye and pillow during sleep, inadequate distribution of tear film, and meibomian gland dysfunction

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24
Q

what is floppy iris syndrome

A

complication during cataract surgery, floppy iris will come out of incision

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25
Q

how many cilia (eyelashes) are in the upper lid

A

100-150

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26
Q

how many cilia (eyelashes) are in the lower lid

A

50-75

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27
Q

what is the life-span of the cilia (eyelashes)

A

3-5 months

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28
Q

if an eyelash is forcibly removed, how long until it grows back

A

about 2 months

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29
Q

what is the chief secretion of the eyelid

A

sebum, oily material from the meibomian glands

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30
Q

how many meibomian glands are in each tarsal plate

A

about 30 in each tarsus

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31
Q

what causes the meibomian glands to secrete the sebum

A

pressure on the glands

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32
Q

what is the arterial supply to the eyelids

A

facial system (external carotid artery) and orbital system (internal carotid artery)

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33
Q

what is the venous drainage of the eyelids

A

superficial (pre-tarsal) system and deep (post tarsal) system

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34
Q

what are the lymphatic systems in the eyelid

A

superficial or pre-tarsal plexus and deep or post-tarsal plexus

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35
Q

what would be affected on the face with paralysis of CN 7

A

causes a brow to be lower on the affected side, lowering of the corner of the mouth

36
Q

weakness of which CN would cause ptosis of the upper lid

A

CN 3 oculomotor

37
Q

paralysis of which CN would cause complete closure of the upper lid

A

CN 3 oculomotor

38
Q

complete paralysis of which muscle would cause complete closure of the upper lid

A

the levator

39
Q

why wouldn’t you have diplopia with a third nerve palsy

A

the eyelid would be completely closed (if you lifted the lid the patient would have diplopia)

40
Q

what muscle would try to compensate in weakness of the levator superioris

A

the frontalis muscle would contract in an attempt the raise the upper lid

41
Q

what would sympathetic paralysis of Mullers muscle cause

A

a minor degree of ptosis (component of Horner’s syndrome)

42
Q

what drug causes reversal of the ptosis of sympathetic paralysis

A

weak solutions of epinephrine (topical)

43
Q

what are the 3 symptoms of Horner’s syndrome

A

ptosis, miosis and anhydrosis (usually half the face)

44
Q

what are the 3 muscles of the eyebrow

A

the frontalis, orbicularis oculi, and corrugator supercilii

45
Q

what does the frontalis muscle do

A

raises the brow in expression of surprise

46
Q

where is the frontalis muscle located

A

oriented radially over the forehead

47
Q

what does the corrugator supercilii do

A

pulls eyebrows together (frown)

48
Q

what is Bell’s phenomenon

A

the globe turns upward as the eyelids are forced closed, not found during normal blinking

49
Q

what are the 3 primary sensory causes of reflex blinking

A

tactile, optic (strong lights) and auditory sensations

50
Q

what is a dazzle reflex

A

the involuntary avoidance response to a light shined into the eye

51
Q

what is a menace reflex

A

blink reflex caused by a sudden motion towards the eye

52
Q

what are two examples of common optically initiated blink reflexes

A

dazzle and menace reflexes

53
Q

what is an aesthesiometer

A

an instrument used to measure the corneal reflex

54
Q

what is a reflex blink

A

high-speed response to tactile and proprioceptive (detects motion) stimuli

55
Q

what is blepharospasm

A

slow, sustained closure to nocieptive (pain) stimuli

56
Q

what is spontaneous blinking

A

occurs on a regular basis without external stimuli

57
Q

what may cause the rate a person has spontaneous blinking

A

levels of visual activity, emotional states and environmental conditions (dryness or windiness)

58
Q

do infants have spontaneous blinking

A

it is extremely low or absent in infants

59
Q

which eyelid moves during spontaneous blinking

A

the upper lid does the most movement, lower lid remains stationary

60
Q

what type of motion does the palpebral fissure make during a blink

A

a zipper-like motion lateral to medial

61
Q

what is the spontaneous blink rate

A

15 x per minute

62
Q

what is the duration of a blink

A

300-400 msec

63
Q

what is the average time between blinks

A

2.8 sec

64
Q

what causes a blepharospasm

A

an idiopathic disorder of neuromuscular control (orbicularis oculi)

65
Q

what treatment can be offered for blepharospasms

A

temporary relief with botulinum-A toxin (Botox) every 3 months

66
Q

what is myokymia

A

fibrillary twitching of the eyelids

67
Q

what is dystonias

A

involuntary muscle contraction and slow repetitive movement

68
Q

what causes myokymia

A

fatigue, thyrotoxicosis, or stress (most common)

69
Q

what is lagophthalmos

A

incomplete closure of eyes during sleep

70
Q

what can lagophthalmos cause

A

desiccation and excessive exposure of the lower portions of the cornea

71
Q

what causes an ectropion

A

weakness of the orbicularis oculi, age-related or weakness of CN 7 of Bells Palsy

72
Q

what are the symptoms of ectropion

A

epiphora (excessive tearing) and poor blink closure

73
Q

what is senile or age-related ectropion

A

secondary to loss of tone and loss of orbital fat deep to the eye

74
Q

what are characteristics of late stage trachoma (chlamydia infection) and ocular pemphigus

A

cicatrical entropion and trichiasis

75
Q

what are the dimensions of a normal palpebral fissure

A

8-11mm wide (vertically) and 27-30mm long (horizontally)

76
Q

what would cause a widening of the palpebral fissure

A

any process that results in proptosis or forward movement of the globe within the orbit

77
Q

what would cause a narrowing of the palpebral fissure

A

abnormal recession of the globe into the orbit

78
Q

which measurement, exophthalmos or lid retraction, would provide more important information in thyroid eye disease

A

the degree of lid retraction (measure the vertical palpebral fissure)

79
Q

what is Collier’s Sign

A

retraction of the upper eyelid in thyrotoxicosis

80
Q

what is Von Grafe’s Sign

A

delay of movement of the upper lid when shifting gaze from up to down; causes a staring expression

81
Q

what is the length of time that is required for our brain to detect that the visual input was obscured

A

30 msec

82
Q

If the duration of a blink is 300-400 msec and it takes 30 msec to detect obscured visual input, why don’t we realize when we are blinking

A

the brain learns to suppress the feeling over time

83
Q

who might experience lagophthalmos

A

common in a few individuals and a consequence of some diseases

84
Q

why is measuring the exophthalmos in a thyroid eye disease not as helpful as measuring the vertical palpebral fissure

A

exophthalmometry measurements are remarkably similar to normal patients (early in the disease)

85
Q

what are two symptoms of thyrotoxicosis

A

collier’s sign and Von Grafe’s sign

Ocular Physiology (6 decks)

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