External Disease and Cornea

Question 1

True or False. The cornea is avascular.

Answer 1

True

Question 2

Which part of the cornea is nearly spherical?

Answer 2

Central 3-4 mm

Question 3

What are the zones of the cornea?

Answer 3

Central
Paracentral
Peripheral
Limbal

Question 4

What is the corneal apex?

Answer 4

Point of maximum curvature, temporal to the pupillary center

Question 5

Which part of the cornea corresponds to the corneal light reflex?

Answer 5

Corneal vertex

Question 6

What are the layers of the cornea?

Answer 6

Epithelium
Bowman membrane
Stroma
Dua layer
Descemet membrane
Endothelium

Question 7

What is the basement membrane of the corneal endothelium?

Answer 7

Descemet membrane

Question 8

What is the innervation of the cornea?

Answer 8

CN V1 (ophthalmic division of the trigeminal nerve)

Question 9

Which layer of the cornea helps maintain its shape?

Answer 9

Bowman layer

Question 10

Described as the tendency of the cornea stroma to swell due to the presence of interfibrillary proteoglycans and other proteins within

Answer 10

Swelling pressure (SP)

Question 11

Which layer of the cornea ends at the Schwalbe line?

Answer 11

Descemet membrane

Question 12

What is the normal central endothelial cell count?

Answer 12

2,000-3,000 cells/mm2

Question 13

What is the average rate of endothelial cell decrease?

Answer 13

0.6% per year

Question 14

What do you call the hypothesis of migration and differentiation of limbal stem cells?

Answer 14

XYZ hypothesis

X = proliferation and stratification of limbal basal cells
Y = centripetal migration of basal cells
Z = desquamation of superficial cells