Eyelids Flashcards
What are the 6 structures of the eyelids?
Skin
Subcutaneous layer
Muscles
Submuscular areolar layer
Fibrous layer
Palbebral conjunctiva
Three characteristics of skin
- Thin
- Elastic
- Fat Free
How often should people where sunglasses?
After 20 minutes or more in the sun
Blepharochalasis
Orbital fat herniation
Basal cell carcinoma is related to ____ _____ exposure
Ultraviolet radiation (UVR)
Are benign growths of the eyelid evenly or unevenly distributed between upper and lower lids?
evenly
Where are malignant tumors more common (upper or lower lid) ?How much more common?
4 times more common in the lower lid
(Eyebrow protects upper eyelid from sun)
Which muscle elevates the upper lid?
Levator Palpebrae Superioris
Which muscle closes the eyelids?
Orbicularis Oculi
What do the Müeller muscle fibers do?
Modulate position of lids of the open eye
What marks the insertion of the levator on the eyelids?
A fold of skin separating the palpebral from the orbital portion of the lid
The orbicular is is striated/unstriated and voluntary/unvoluntary
Striated Voluntary
What is the function of the orbicular is oculi?
helps hold the lid tightly against the eye, which assists in spreading tears and flushing away waste products
Which nerve innervates the orbicularis oculi?
CN VII (Facial)
What happens with damage to the CN VII in the orbicularis oculi?
leads to dry eye condition, lagophthalmus, dut to inability to close eyelids
Levator palpebrae superioris is striated or unstraited
striated
Where does the levator become tendinous?
At the “aponeurosis of the legator” - where it enters the lid
Which nerve innervates the Levator?
CN III (Oculomotor nerve)
Where is the tarsal muscle, superior and inferior (Muller) found?
Found in the upper and lower lids, lines the levator internally
What happens when sympathetic innervation is damaged?
Droopy lid
Where is the submuscular areolar tissue and what is it?
Loose connective tissue between muscle and tarsal plate - fat free
What is the fibrous layer of the eyelid?
dense fibrous tissue that gives firmness and shape to the eyelids - known as the tarsal plate
Where is the collagen more developed (upper or lower) lid?
upper lid - allows lid to be everted
Upper eyelids are _____ and easily ____
flaccid everted
Floppy Eyelid Syndrome symptoms
- patients present with burning and irritation of eyes
- Contact between eye and pillow during sleep poor apposition of eyelid to globe
- Meibomian gland dysfunction
How many Cilia in upper and lower lids?
100-150 upper
50-75 lower
What is the life span of the cilia?
3-5 months
How long does it take for forcibly removed cilia to regrow?
~2 month
What is the chief secretion of the eyelid?
Sebum - oily material secreted by the meibomian glands
The sebum forms which layer in the eye?
The superficial layer over the pre corneal tear film - slows evaporation of aqueous component
_____ on the glands will cause sebum to be excreted from the openings of the glands at the lid margins
Pressure
What secretes sebum and how many of them?
Meibomian glands ~30 glands
Which other glands are found in the lids?
Accessory lacrimal gland tissue
Glands of Krause
Glands of Wolfring
Arterial supply to the eyelids
Facial system (from external carotid artery Orbital system (from internal carotid artery)
Venous drainage of the eyelids
Superficial (pre-tarsal) system
Deep (post-tarsal) system
Lymphatics of the eyelids are dived into which two systems?
Superficial or pre-tarsal plexus
Deep or post-tarsal plexus
Paralysis of CN 7 can cause the brow to be?
lower on the affected side
Paralysis of CN 3 can cause what versus weakness
Paralysis - complete closure of the upper lid Weakness - ptosis of the upper lid
Sympathetic paralysis can cause
minor ptosis
One of the components of Horner’s syndrome
Strong or weak solutions of epinephrine applied topically will cause reversal of ptosis in sympathetic ptosis
Weak
Function of the corrugator supercilli
pulls eyebrows together (frown)
What happens in Bell’s phenomenon?
globe turns upward as the eyelids are forced closed
What is reflex blinking?
rapid closure movement of short duration
What causes reflex blinking?
External stimuli:
- Strong lights
- Approaching objects
- Loud noises
- Cornel, conjunctival, or ciliary touch
What quantifies the corneal reflex?
an aesthesiometer
In CL wearers the tactile corneal reflex is _______ slightly
dimished
Two examples of blink reflexes
Dazzle reflex
Menance reflex
The reflex blink is a _____-speed response to _____ and ______ stimuli
High Tactile Proprioceptive - detects motion
What is blepharospasm
slow, sustained closure to nociceptive (pain) stimuli
What can changed the regular basis of spontaneous blinking?
Level of visual activity
Emotional states
Environmental conditions (computer users)
Spontaneous blinking is (high or low) in infants
low or absent
Is spontaneous blinking present in blindness?
Yes; does not depend on optic stimulation
What does the lower lid do during spontaneous blinking?
Remain almost stationary (most movement is done by upper lid)
Spontaneous blink rates is?
~15 times per min
What is the duration of the blink?
300-400 msec
average time between blinks is?
2.8 sec
obscuring visual input up to ____ msec is barely detectable but obscuring it greater than ____ msec is easily detectable
3 msec
30 msec
What can give you temporary relief for blepharospasm? How long does it last?
Botulinum-A (botox) ~3 months
Blepharospasm (raises or lowers) IOP?
raises
What is myokymia
Fibrillary twitched of the eyelids
What causes myokymia
fatigue
thyrotoxucosis
physical stress
What is lagophthalmos?
incomplete closure of the eyes during sleep
What is the result of lagophthalmos?
desiccation and excessive exposure of the lower portion of the cornea
Ectropion is what?
a falling away of the lower lid away from the globe
What causes ectropion?
weakness of the orbicularis
What is the result of ectropion?
Epiphora or poor blink closure
What is senile ectropion?
Loss of tone and loss of orbital fat deep to the eye with age
Entropian vs. Ectropian
Entropian - lid turns toward the eye (contact between lashes and corneal surface)
Ectropian - turns away from the eye
In which diseases is entropian a symptom?
Trachoma and ocular pemphigus
The palbebral fissure is usual how wide and how long?
8-11 mm wide
27-30 mm long
A large eye within a shallow orbit will appear as a?
prominent globe with a wider fissure
Proptosis
forward movement of the globe within the orbit
What will proptosis cause?
a widening of the palpebral fissure on the side
In which disease is exophthalmos found?
Thyroid disease
What is exophthalmos?
retraction of the upper eyelids (causes a widening of the palpebral fissure)
The principal component in the apparent exophthalmos os thyroid eye disease is?
The degree of lid retraction (measurement of vertical palpebral fissure may be more important measurement than exophthalmometry)
Exophthalmometry measurements range from ____ to ____ mm in normal subjects (mean of ____ mm) and ____ to _____ mm (mean of ____ mm in thyroid eye disease subjects
12-21 mm
16 mm mean
12-24 mm
18 mm mean
What is Collier’s Sign of Thyroxicosis?
retraction of the upper lid(s)
What is Von Grafe’s Sign of Thyroxicosis?
Delay of movement of the upper lid when shifting gaze from up to down; causes staring expression
