Cornea Anatomy

Question 1

Tear film index?

Answer 1

n=1.336

Question 2

Cornea index?

Answer 2

n=1.376

Question 3

Where is the cornea thickest?

Answer 3

PERIPHERY (0.67mm)

vs center (0.55mm)

Question 4

Anterior radius of curvature for the cornea?

Answer 4

7.8mm

Question 5

Posterior radius of curvature for the cornea?

Answer 5

6.5mm

Question 6

Avg ant H and V diameter of cornea?

Answer 6

11. 7 mm H

10. 6 mm V

Question 7

How thick is corneal epi?

Answer 7

50 um

Question 8

What connect basement membrane to corneal epi?

Answer 8

Hemidesmosomes

Question 9

How thick is bowman’s layer?

Answer 9

12 um

NOTE: will scar

Question 10

How thick is stroma?

Answer 10

450 um

NOTE: keratocytes

Question 11

How thick is descemet’s?

Answer 11

5-15 um

NOTE: born w 5um die w 15

Question 12

Endothelium thickness?

Answer 12

5um

NOTE: most mitochondria and pumps located here

Question 13

Which is the ONLY layer in the cornea to contain zonula occludens?

Answer 13

Corneal Epithelium

NOTE: zonula occludens/tight junctions and desmosomes form a tight barrier btwn cells to impede the intercellular movement of particles

Question 14

What are wing cells joined by?

Answer 14

Desmosomes

Question 15

What is the only miotic layer of the corneal epithelium?

Answer 15

Basal layer

NOTE: this layer divides into wing and hemidesmosome

Question 16

Limbal stem cell deficiency contributes to poor corneal epithelial maintenance in people with what diseases?

Answer 16

1. Aniridia
2. SJS
3. Alkali corneal burns

Question 17

What are the 2 layers in all basement membranes of the body?

Answer 17

1. Basal lamina (secreted by epi cells)

2. Reticular lamina (produced by underlying stromal cells)

Question 18

What are the 3 risks for recurrent corneal erosions?

Answer 18

1. Poor hemidesmosome attachments
2. Epithelial BM dystrophy
3. Age related thickening of the BM

Question 19

What type of collagen is Bowman’s composed of?

Answer 19

Type 1 collagen

NOTE: acellular layer

Question 20

What are conditions related to Bowman’s layer?

Answer 20

1. Band keratopathy
2. Pterygium
3. Crocodile Shagreen
4. Reis-buckler’s dystrophy
5. Keratoconus (T-DOME)
6. Refractive Sx

Question 21

What collagen is corneal stroma composed of?

Answer 21

Type 1

Question 22

What produces the collagen in corneal stroma?

Answer 22

Keratocytes

NOTE: these also make ECM

Question 23

How are corneal stroma fibrils spaced?

Answer 23

Evenly by 30nm lamellae

Question 24

What does the ground substance in stroma function to do?

Answer 24

Contain GAGs which attract water creating PERFECT spacing

NOTE: the predominant GAG is keratin sulfate

Question 25

What type of collage in descemet' membrane made of?

Answer 25

Type 4

Question 26

What are the disorders related to descemet's membrane?

Answer 26

1. Hydrops 2. Haab's striae 3. Hassall-Henle Bodies

Question 27

What kind of cells is endothelium made of?

Answer 27

Squamous cells NOTE: These epithelia are common where absorption or transport of materials is important. They also play a role in diffusion, osmosis and filtration. This makes them important in the kidney, in the alveoli of lungs and in the walls of capillaries.

Question 28

How are endothelium linked together (apical or basal)?

Answer 28

Apical borders facing anterior chamber by MACULAE OCCLUDENS (leaky)

Question 29

Where does the corneal get nutrients from?

Answer 29

1. Diffusion from aqueous humor 2. Limbal conj and episcleral cap networks 3. Palpebral conj networks

Question 30

Where is the main source of O2 to the cornea during sleep?

Answer 30

ANTERIORLY=palpebral conj POSTERIORLY=aqueous

Question 31

Where does the LPCN and SPCN enter the cornea?

Answer 31

MID-STROMA

Question 32

After traveling into the stroma, what happens to the corneal nerves?

Answer 32

They lose their myelin sheath Now they are HIGHLY SENSITIVE AND NAKED w nociceptors that mediate pain

Question 33

Where are nerve networks formed?

Answer 33

1. Epithelium - Intraepithelial plexus 2. Anterior Stroma/Bowman's Layer - Subepithelial plexus 3. Mid stroma - stromal plexus