Eyelids Flashcards
why is the skin in the eyelids fat free
so they are lighter for the muscles to lift for how often we blink
what is blepharochalsis
inflammation of the eyelid
what type of carcinoma is related to UVR exposure
basal cell carcinoma
which lids (upper or lower) are affected by benign growths
both have an equal change of getting them
which lid (upper or lower) has a greater chance of developing a malignant tumor
the lower lid is four times more likely to get one
why wouldn’t the upper lid be as common in getting malignant tumors
the eyebrows protect the upper lid from the sun
what does the levator palpebrae superioris do
elevates the upper lid (striated muscle)
what do the Muller muscle fibers do
modulate position of lids of the open eye
what marks the palpebral portion from the orbital portion of the lid
the insertion of the levator palpebrae superioris (superior palpebral sulcus)
when would someone have an absence of the superior palpebral sulcus
certain ethnicities will not have a distinct line or if there is ptosis (especially congenital)
what does the orbicularis oculi do
(striated voluntary muscle) closes the lids and helps hold the lid tightly against the eye, assists in spreading tears and flushing waste
what innervates the orbicularis oculi
CN 7- facial
what would happen if CN 7-facial of the orbicularis oculi was paralyzed
dry eye conditions, lagophthalmus (inability to close lids)
at what point does the levator palpebrae superioris become tendinous
as it enters the lid becoming the “aponeurosis of the levator”
what innervates the levator palpebrae superioris
CN 3 oculomotor nerve
what type of innervation does the tarsal muscle (Mullers muscle) superior and inferior have
sympathetic innervation
what does contraction of the tarsal muscle (mullers) do
aids the action of the levator
what would damage to the tarsal muscle do
damage to the sympathetic innervation causes a droopy lid (ptosis)
what type of tissue is in the submuscular areolar tissue
loose connective tissue between the muscle and tarsal plate (fat free)
what is in the fibrous layer of the eyelid
dense fibrous tissue and collagen that gives firmness and shape to lids (tarsal plate); more developed collagen in the upper lid
what is floppy eyelid syndrome
the upper lids are flaccid and easily everted
what causes floppy eyelid syndrome
decreased tarsal elastin and genetic abnormalities of collagen and elastin
what are the symptoms of floppy eyelid syndrome
burning and irritation, contact between eye and pillow during sleep, inadequate distribution of tear film, and meibomian gland dysfunction
what is floppy iris syndrome
complication during cataract surgery, floppy iris will come out of incision
how many cilia (eyelashes) are in the upper lid
100-150
how many cilia (eyelashes) are in the lower lid
50-75
what is the life-span of the cilia (eyelashes)
3-5 months
if an eyelash is forcibly removed, how long until it grows back
about 2 months
what is the chief secretion of the eyelid
sebum, oily material from the meibomian glands
how many meibomian glands are in each tarsal plate
about 30 in each tarsus
what causes the meibomian glands to secrete the sebum
pressure on the glands
what is the arterial supply to the eyelids
facial system (external carotid artery) and orbital system (internal carotid artery)
what is the venous drainage of the eyelids
superficial (pre-tarsal) system and deep (post tarsal) system
what are the lymphatic systems in the eyelid
superficial or pre-tarsal plexus and deep or post-tarsal plexus
what would be affected on the face with paralysis of CN 7
causes a brow to be lower on the affected side, lowering of the corner of the mouth
weakness of which CN would cause ptosis of the upper lid
CN 3 oculomotor
paralysis of which CN would cause complete closure of the upper lid
CN 3 oculomotor
complete paralysis of which muscle would cause complete closure of the upper lid
the levator
why wouldn’t you have diplopia with a third nerve palsy
the eyelid would be completely closed (if you lifted the lid the patient would have diplopia)
what muscle would try to compensate in weakness of the levator superioris
the frontalis muscle would contract in an attempt the raise the upper lid
what would sympathetic paralysis of Mullers muscle cause
a minor degree of ptosis (component of Horner’s syndrome)
what drug causes reversal of the ptosis of sympathetic paralysis
weak solutions of epinephrine (topical)
what are the 3 symptoms of Horner’s syndrome
ptosis, miosis and anhydrosis (usually half the face)
what are the 3 muscles of the eyebrow
the frontalis, orbicularis oculi, and corrugator supercilii
what does the frontalis muscle do
raises the brow in expression of surprise
where is the frontalis muscle located
oriented radially over the forehead
what does the corrugator supercilii do
pulls eyebrows together (frown)
what is Bell’s phenomenon
the globe turns upward as the eyelids are forced closed, not found during normal blinking
what are the 3 primary sensory causes of reflex blinking
tactile, optic (strong lights) and auditory sensations
what is a dazzle reflex
the involuntary avoidance response to a light shined into the eye
what is a menace reflex
blink reflex caused by a sudden motion towards the eye
what are two examples of common optically initiated blink reflexes
dazzle and menace reflexes
what is an aesthesiometer
an instrument used to measure the corneal reflex
what is a reflex blink
high-speed response to tactile and proprioceptive (detects motion) stimuli
what is blepharospasm
slow, sustained closure to nocieptive (pain) stimuli
what is spontaneous blinking
occurs on a regular basis without external stimuli
what may cause the rate a person has spontaneous blinking
levels of visual activity, emotional states and environmental conditions (dryness or windiness)
do infants have spontaneous blinking
it is extremely low or absent in infants
which eyelid moves during spontaneous blinking
the upper lid does the most movement, lower lid remains stationary
what type of motion does the palpebral fissure make during a blink
a zipper-like motion lateral to medial
what is the spontaneous blink rate
15 x per minute
what is the duration of a blink
300-400 msec
what is the average time between blinks
2.8 sec
what causes a blepharospasm
an idiopathic disorder of neuromuscular control (orbicularis oculi)
what treatment can be offered for blepharospasms
temporary relief with botulinum-A toxin (Botox) every 3 months
what is myokymia
fibrillary twitching of the eyelids
what is dystonias
involuntary muscle contraction and slow repetitive movement
what causes myokymia
fatigue, thyrotoxicosis, or stress (most common)
what is lagophthalmos
incomplete closure of eyes during sleep
what can lagophthalmos cause
desiccation and excessive exposure of the lower portions of the cornea
what causes an ectropion
weakness of the orbicularis oculi, age-related or weakness of CN 7 of Bells Palsy
what are the symptoms of ectropion
epiphora (excessive tearing) and poor blink closure
what is senile or age-related ectropion
secondary to loss of tone and loss of orbital fat deep to the eye
what are characteristics of late stage trachoma (chlamydia infection) and ocular pemphigus
cicatrical entropion and trichiasis
what are the dimensions of a normal palpebral fissure
8-11mm wide (vertically) and 27-30mm long (horizontally)
what would cause a widening of the palpebral fissure
any process that results in proptosis or forward movement of the globe within the orbit
what would cause a narrowing of the palpebral fissure
abnormal recession of the globe into the orbit
which measurement, exophthalmos or lid retraction, would provide more important information in thyroid eye disease
the degree of lid retraction (measure the vertical palpebral fissure)
what is Collier’s Sign
retraction of the upper eyelid in thyrotoxicosis
what is Von Grafe’s Sign
delay of movement of the upper lid when shifting gaze from up to down; causes a staring expression
what is the length of time that is required for our brain to detect that the visual input was obscured
30 msec
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
the brain learns to suppress the feeling over time
who might experience lagophthalmos
common in a few individuals and a consequence of some diseases
why is measuring the exophthalmos in a thyroid eye disease not as helpful as measuring the vertical palpebral fissure
exophthalmometry measurements are remarkably similar to normal patients (early in the disease)
what are two symptoms of thyrotoxicosis
collier’s sign and Von Grafe’s sign
