Cornea Vol. 1

Question 1

At what week of gestation does the eye begin to develop?

Answer 1

Week 4

Question 2

From what embryologic germ layer does the optic vessel arise from?

Answer 2

Neuroectoderm

Question 3

At what week of gestation does the optic cup form?

Answer 3

Week 5

Question 4

What does the first wave of mesenchymal cells from the neural crest ectoderm become?

Answer 4

Corneal endothelium

Question 5

What does the second wave of mesenchymal cells from the neural crest ectoderm become?

Answer 5

Corneal stroma and sclera

Question 6

From what embryologic tissue layer does the corneal epithelium arise?

Answer 6

Surface ectoderm

Question 7

At what month of gestation do the eyelids fuse?

Answer 7

Month 2

Question 8

At what month of gestation does Bowman’s layer and scleral spur form?

Answer 8

Month 4

Question 9

At what month of gestation do the eyelids begin to open?

Answer 9

Month 5

Question 10

At birth, how large is the globe in proportion to adult size?

Answer 10

80% of adult size

Question 11

How thick are the eyelids at the eyelid margin?

Answer 11

0.5 mm

Question 12

How thick are the eyelids at the oribital rim?

Answer 12

1.0 mm

Question 13

How often are eyelashes normally replaced?

Answer 13

Every 3 to 5 months

Question 14

How long does it take for eyelashes to regrow if trimmed?

Answer 14

2 weeks

Question 15

How long does it takes to eyelashes to grow if epilated?

Answer 15

2 months

Question 16

What type of glands are the glands of Moll?

Answer 16

Apocrine sweat glands

Question 17

What type of glands are the glands of Zeis?

Answer 17

Sebaceous glands

Question 18

What nerve provides sensory innervation to the eyelids?

Answer 18

Supraorbital nerve (CN V1)

Question 19

What portion of the obicularis oculi is responsible for voluntary eyelid closure?

Answer 19

Orbital and preseptal

Question 20

What portion of the obicularis oculi musce is responsible for subconscious blinking?

Answer 20

Pretarsal

Question 21

What is the normal rate of blinking in the average person?

Answer 21

One blink per 3-4 seconds

Question 22

In what direction do the eyelids move during a blink?

Answer 22

Medially and towards each other

Question 23

What are the two major sources of blood supply to the eyelid?

Answer 23

Facial artery and ophthalmic artery

Question 24

What are the two major venous sources of drainage of the eyelids?

Answer 24

Superior temporalveins to the jugular vein and ophthalmic vein to the cavernous sinus

Question 25

What is the lymphatic drainage of the lateral eyelid?

Answer 25

Preauricular lymph node

Question 26

What is the lymphatic drainage of the medial eyelid?

Answer 26

Submandibular and submental lymph nodes

Question 27

How thick is the tarsus?

Answer 27

0.75 mm

Question 28

How tall is the tarsus in1he upper eyelid? Lower eyelid?

Answer 28

Upper eyelid tarsus- 10 mm Lower eyelid tarsus -4 mm

Question 29

What does the caruncle contain?

Answer 29

Hairs and sebaceous glands

Question 30

What is the lies directly beneath and is adherent to the bulbar conjunctiva?

Answer 30

Tenon’s capsule

Question 31

What do the palisades of Vogt contain?

Answer 31

Limbal stem cells

Question 32

What type of epithelium is found in the tarsal conjunctival? Fomix? Bulbar?

Answer 32

Tarsus- stratified cuboidal Fornix- stratified columnar Bulbar - stratified squamous