Flashcards in Cornea Vol. 1 Deck (32)
At what week of gestation does the eye begin to develop?
From what embryologic germ layer does the optic vessel arise from?
At what week of gestation does the optic cup form?
What does the first wave of mesenchymal cells from the neural crest ectoderm become?
What does the second wave of mesenchymal cells from the neural crest ectoderm become?
Corneal stroma and sclera
From what embryologic tissue layer does the corneal epithelium arise?
At what month of gestation do the eyelids fuse?
At what month of gestation does Bowman's layer and scleral spur form?
At what month of gestation do the eyelids begin to open?
At birth, how large is the globe in proportion to adult size?
80% of adult size
How thick are the eyelids at the eyelid margin?
How thick are the eyelids at the oribital rim?
How often are eyelashes normally replaced?
Every 3 to 5 months
How long does it take for eyelashes to regrow if trimmed?
How long does it takes to eyelashes to grow if epilated?
What type of glands are the glands of Moll?
Apocrine sweat glands
What type of glands are the glands of Zeis?
What nerve provides sensory innervation to the eyelids?
Supraorbital nerve (CN V1)
What portion of the obicularis oculi is responsible for voluntary eyelid closure?
Orbital and preseptal
What portion of the obicularis oculi musce is responsible for subconscious blinking?
What is the normal rate of blinking in the average person?
One blink per 3-4 seconds
In what direction do the eyelids move during a blink?
Medially and towards each other
What are the two major sources of blood supply to the eyelid?
Facial artery and ophthalmic artery
What are the two major venous sources of drainage of the eyelids?
Superior temporalveins to the jugular vein and ophthalmic vein to the cavernous sinus
What is the lymphatic drainage of the lateral eyelid?
Preauricular lymph node
What is the lymphatic drainage of the medial eyelid?
Submandibular and submental lymph nodes
How thick is the tarsus?
How tall is the tarsus in1he upper eyelid? Lower eyelid?
Upper eyelid tarsus- 10 mm Lower eyelid tarsus -4 mm
What does the caruncle contain?
Hairs and sebaceous glands