Corneal Repair

Question 1

What are the roles of corneal integrins?

Answer 1

• facilitates interactions between cells and extracelluar matrix
• matrix assembly
• impact cell adhesion and formation of junctions
• senses changes in the extracelluar environment
• communicated to the cell nucleus by an alteration in the cytoskeleton

Question 2

What are cytokines?

Answer 2

Signaling molecules.

They are released in health and damaged corneas

Question 3

What are the 2 roles of cytokines?

Answer 3

• communicates between cells and surrounding tissues

- controls the growth of corneal cells

Question 4

What are the 3 roles of growth factors?

Answer 4

• promotes proliferation of corneal cells
• induces migration of cells
• maintains corneal transparency

Question 5

What are the 3 wound healing biomolecules?

Answer 5

• integrins
• cytokines
• growth factors

Question 6

In which epithelial layer can cells divide?

Answer 6

Basal (through mitosis)

Question 7

Name the 3 epithelial layers?

And how thick are they?

Answer 7

• basal layer: 1 cell thick
• wing layer:2-3
• surface layer: 2

Question 8

What is the process of epithelial replacement

Answer 8

Stem cells in the peripheral cornea divide–>new cells move toward the center to become basal cells–>BC move up and become wing cells–>WC move up and become surface cells–>SC shed into tear film–>turn over in 7 days

Question 9

When there’s a corneal injury what happens to mitosis?

Answer 9

It stops

Question 10

What’s released if the cornea is damaged?

Answer 10

Growth factors and cytokines

Question 11

The process of wound healing

Answer 11

• mitosis stops
• growth factors and cytokines are released
• hemidesmosomes dissemble along the wound edge
• this changes the cytoskeleton which causes cells to migrate and cover the wound
• you get adhesion molecules
• –epithelial sheet adheres to basement membrane
• the defect is covered by a single layer of cells and junctions are formed between the neighboring cell
• mitosis resumes and normal cell density is reached
• hemidesmosomes replace biochemical bonds holding basal cells

Question 12

Cell migration requires control of what 3 things

And what do these preserve

Answer 12

• hemidesmosomes
• cytoskeleton structure
• cell-matrix adhesion

The structural integrity of epithelial sheet

Question 13

How long does it take small lesions of the epithelium to heal?

Answer 13

24-48 hours

Question 14

How long does it take if the basement membrane of the epithelium is damaged?

Answer 14

Several months for normal hemidesmosomes

Question 15

T/F: the epithelium is usually scar free

Answer 15

True

Question 16

During recurrent corneal erosion the corneal epithelium sloughs off either ___ or ___

Answer 16

Continually or periodically

Question 17

What are the 2 causes of recurrent corneal erosion?

Answer 17

• Poor adhesion between Epithelium and Basement Membrane

- Poor adhesion between Basement Membrane and underlying tissue (stroma)

Question 18

Recurrent corneal erosion occurs….

Answer 18

-after incomplete healing of an abrasion (hemidesmosomes malformed) OR
by epithelial basement membrane dystrophy

Question 19

If someone comes in every few months and says that they have pain and irritation or have it all the time, and you put fluorescein and see spots on the cornea what could this be?

Answer 19

Recurrent corneal erosion

Question 20

What are the treatments of recurrent corneal erosion?

Answer 20

• artificial tears
• antibiotic
• bandage CLs
• anterior stromal micropuncture
• superficial karate to your (removal of epithelium)
• PTK

Question 21

Is bowmans layer cellular or acellular?

Answer 21

Acellular

Question 22

Bowmans layer is composed primarily of ___

Answer 22

Collagen

Question 23

T/F: BL’s is highly resistant to pentration or damage

Answer 23

True

Question 24

T/F: Bowmans layer does not regenerate

Answer 24

True

Question 25

What replaces the bowmans layer when damaged?

Answer 25

Stroma scar tissue or epithelium

Question 26

Bowmans layer is ___ to the epithelium

Answer 26

Posterior

Question 27

The stroma is composed of?

Answer 27

- collagen fibrils - keratocytes - extracelluar ground substances

Question 28

When the stroma is injured what occurs?

Answer 28

Keratocytes increase in number; some stimulated to become myofibroblasts--> cause wound bed to contract--> wound coverage by epithelium over defect

Question 29

Regenerated stromal collagen is ____ than the original fibrils and alignment and organization are not as ____ -> ______ probability of scarring

Answer 29

- larger - precise - increasing

Question 30

After healing of the stroma is complete what happens to the myofibroblasts

Answer 30

They undergo apoptosis or revert back to keratocytes

Question 31

How long does it take the stroma to heal?

Answer 31

Months

Question 32

The basement membrane of the endothelium

Answer 32

Descemets membrane

Question 33

T/F: descemets membrane remains the same throughout life

Answer 33

False. It thickens

Question 34

Descemets membrane is composed of ___

Answer 34

Collagen fibrils

Question 35

When DM is injured, its regenerated by what?

Answer 35

Stroma keratocytes and the endothelium

Question 36

The single layer of flattened cells that is the most posterior part of the cornea

Answer 36

Endothelium

Question 37

What are the shape of the endothelium cells?

Answer 37

Polyhedral

Question 38

The basal part of the endothelium rests on the ____ and the apical surface lines the ___

Answer 38

- descemets membrane | - anterior chamber

Question 39

T/F: there is little mitosis that occurs in the endothelium

Answer 39

True

Question 40

What is the process of wound healing in the endothelium

Answer 40

-Neighboring cells enlarge and flatten to cover area of cell loss, this leads to a decrease in endothelial cell density -the cells remodel into polyhedral shape -Pump and Barrier functions are reestablished ----Increase in ion pumps to compensate for loss of pumps from cells loss