Eyelids Flashcards
Describe skin of eyelids?
fat free, thin, elastic
Describe benign and malignant growths in eyelids?
Both upper and lower eyelids have equal amounts of benign growths; malignant are more than 4x likely to develop in lower eyelid because the eyebrow protects upper lid from sun
Levator Palpebrae Superioris
elevates upper lid; striated muscle; becomes tendinous as it enters the lid; innervated by oculomotor nerve 3
Obicularis Oculi? Innervated by?
closes lids; striated voluntary muscle; helps in spreading tears and flushing away waste products; innervated by cranial nerve 7; paralysis leads to dry eye syndrome, lagopthalmus
Muller Muscle Fibers
modulate position of lids of the open eye; sympathetic innervation (damage leads to droopy eye); found in both lids; lines levator internally; contraction aids in action of levator; wide eyed expression of fear
Insertion of Levator Palpebrae Superioris
crease marked between the palpebral and orbital parts of eyelid
Lack of fold means?
Ptosis; levator did not enter correctly
Submuscular Areolar Tissue
loose connective tissue between muscle and tarsal plate; fat free
Fibrous Layer
dense fibrous tissue that gives shape and firmness; known as tarsal plate; collagen more developed in upper lid than lower (eversion)
Floppy Eyelid Syndrome
upper lid can be everted more than usual ; decreased tarsal elastin; genetic abnormalities of collagen or elastin
eyes burn and irritated, contact with eyelid and pillow ; poor apposition of eyelid to globe inadequate spreading of tear film; meibomian gland dysfunction
associated with sleep apnea
Cilia
upper= 100-150; lower 50-75; lifespan 3-5 months; forcibly removed will grown back in 2 months (leprocy, psych disorders)
What is chief secretion and what is it secreted by?
sebum; meibomian glands. forms superficial layer over precorneal tear film that slows evaporation of aqueous
Arterial Supply
Facial system; orbital system
Venous Drainage
superficial (pre) and deep (post)
Lymphatic System
deep and superficial
Damage of CN 7
causes brow to droop down on side affected
Paralysis of CN 3
Ptosis of upper eyelid; complete closure of lid; frontalis works harder
Paralysis of Sympathetic Nerve (Muller’s Muscle)
causes minor ptosis; associated with Horner’s syndrome; can be reversed by weak epinephrine (topical)
What are the muscles of the eyebrow?
Frontalis, Obicularis Oculi, Corrugator supercilli
Frontalis
Raises eyebrows; oriented radially over forehead
Obicularis Oculi
found in eyelid; has orbital, palpebral, and ciliary portions ; muscle fibers oriented concentrically; sphincter action closes eyelids
Corrugator supercili
pulls eyebrows together; frowning
Bell’s phenomenom
Turns globe upward as lids are forcefully closed / does not occur with reflex blinking (cornea turns upward to avoid drying or becoming opaque)
Sensory modalities stimulated during reflex blinking (3)?
Tactile, optic, and auditory sensations; touch, Strong lights, Approaching objects, loud noise
Reflex blinking
Reflex blinking is a rapid closure movement of short duration
What quantifies corneal reflex?
Aesthesiometer
Corneal reflex diminished in?
contact lens wearers
What are common reflexes that initiate reflex blinking?
Dazzle reflex and menace reflex
Blephoraspasm
Slow sustained closure to painful stimuli
An idiopathic disorder of neuromuscular control (orbicularis muscle)
Results in simultaneous bilateral, symmetrical, progressive, involuntary closure of both eyes
Raises IOP; Temporary relief with botulinum-A toxin
Spontaneous Blinking
blinking that occurs on regular bases withput external stimuli
Name conditions in which spontaneous blinking can change?
Can change secondary to level of visual activity, emotional states, and environmental conditions
(Clinical point – Computer users, any activity that involvesincreased attention)
Spontaneous Blinking in Infants?
low or absent
Spontaneous Blinking in Blind
present; does not depend on optical stimulation
Spontaneous Blinking motion
most motion occurs in upper lid; lower lid stationary; palpebral fissure closes laterally to medially flushing tears through puncta
Rate of Spontaneous Blinking
Spontaneous blink rate is ≈ 15x per min; Duration of blink is 300-400 msec; Average time between blinks is 2.8 sec
Voluntary Blinking
consciously initiation of closure of one eye. Most ppl blink freely with left eye
Myokymbia and causes of aggravation?
fibrillary twitching ; fatigue, psychological stress, and thyrotoxicosis
Lagophthalmos
incomplete closure of eyes during sleep; results in desiccation and excessive exposure of lower portions of cornea
Ectropian
falling away of the lower eyelid away from globe; droopiness
What causes ectropian?
weakness of obicularis
Results of ectropian?
poor blink closure and epiphora
Senile Ectropian
loss of tone and loss of orbital fat
Entropian
turning in of eyelid
Results of Entropian?
Trichiasis (turning in of eye lashes) ; trachoma (Chlamydia infection) and ocular pemphigoid;
Loss of transparency or cornea (cause it to get opaque)
Autoimmune reaction causes conjunctiva to shrinkScarring and shrinking
Palpebral Fissure
8-11 mm wide; 27-30mm long
Proptosis or large eye with shallow pits= larger fissure
Recession of globe= narrow fissure
Exophthalmos
Seen in Thyroid Disease
Retraction of the upper eyelids causes a widening of the palpebral fissure
Thyroid eye disease: Exophthalmometry measurements are remarkably similar to normal patients
Vertical fissure measurements are better
Exopthalmos Measure
Measurements range from 12 to 21 mm -normal subjects
mean of 16 mm
thyroid eye disease yield values ranging from 12 to 24 mm
mean of 18 mm.
Measurements of greater than 19 mm however, were found in only about 5% of normals, while 32% of those with thyroid eye disease fell above this level.
