Corneal Function

Question 1

How does the cornea refract light?

Answer 1

curvature of ant and post surface
change in refractive index
corneal thickness

Question 2

Power of Cornea

Answer 2

40-48

43

Question 3

Maximizing Corneal Light Transmission

Answer 3

smooth optical surface / tear film
regularity of epithelial cells
no blood vessels
correct arrangement of collagen in stroma
<1% light scatter

Question 4

Corneal Protective Functions

Answer 4

blink away microbes = decrease infections
prevent retinal damage by blocking UV and penetrating injuries
fast healer

Question 5

Normal CV of Endothelium

Answer 5

0.25

Question 6

Normal Endothelial Cell Density

Answer 6

2000 cells/mm2

Question 7

Hexagonality of Endothelial Cells

Answer 7

69%

Question 8

Size of Stromal Collagen Fibrils

Answer 8

300A

Question 9

Spacing between Stromal Collagen Fibrils

Answer 9

550A

Question 10

Stroma should consist of ________% water

Answer 10

75 - 80

Question 11

Dua’s Layer can withstand up to _______ pressure

Answer 11

200 kPa

Question 12

Epithelium has ______ that help maintain hydration

Answer 12

tight junctions

Question 13

Stroma uses ________ to pull water in

Answer 13

anionic proteoglycans

Question 14

Endothelium plays what role in hydrating the cornea?

Answer 14

leaks fluids

Question 15

Corneal Hydration is dependent on…

Answer 15

barrier function of epithelium and endothelium
water and ion transport through epi and endo membranes
anionic characteristics of materials in stromal matrix

Question 16

Pressures of 50 mmHg has what effect?

Answer 16

moves extra water into stroma from ant chamber, which overwhelms the endothelial transport system

Question 17

Corneal abrasions can break the barriers of….

Answer 17

zonular occludens

causes edema/ haziness

Question 18

Allows the cornea to heal so rapidly

Answer 18

peptide growth factors

Question 19

Corneal Ulcer

Answer 19

infectious condition that compromises that integrity of the epithelium

Question 20

Hydrophobic/ nonpolar parts of cornea

Answer 20

epithelium and endothelium

Question 21

Hydrophilic/ polar part of cornea

Answer 21

stroma

sucks water in

Question 22

Is the epithelium permeable to ions?

Answer 22

no