Cornea - Functions & Regeneration (M2)

Question 1

function of cornea

Answer 1

refract light.
absorb and transmit light

Question 2

what does the cornea allow light to do

Answer 2

reach the retina and allow for vision

Question 3

wavelengths of light that enter cornea

Answer 3

290 - 2000 nm

Question 4

290 - 320 nm (UV - B)

Answer 4

damaging to cells
90% absorbed by ozone; 10% absorbed by cornea

Question 5

320 - 400 nm (UV - A)

Answer 5

least harmful
partially absorbed by cornea; majority absorbed by lens

Question 6

400 - 700 nm (visible light)

Answer 6

transmitted by cornea
allows for vision

Question 7

700 - 2000 nm (infrared light)

Answer 7

transmitted by cornea

Question 8

what must cornea be for optimal light transmission

Answer 8

transparent

Question 9

how often does epithelium regenerate

Answer 9

7 - 10 days

Question 10

what are basal cells replaced by

Answer 10

limbal stem cells

Question 11

what does epithelial damage result in

Answer 11

increased risk of infection
generally scar-free.
can result in stromal edema.

Question 12

how long does it take a small epithelium injury to heal

Answer 12

overnight

Question 13

how long does it take to heal if basement or hemidesmosomes are damaged

Answer 13

months.
if hemidesmosomes are malformed –> recurrent corneal erosion (RCE)

Question 14

what is RCE

Answer 14

condition where every couple of days the corneal epithelium sloughs off continually as a result of cells not properly adhering to the layer below it

Question 15

how long does it take to heal if corneal sensory nerves are damaged

Answer 15

wound healing is impaired.
reduced mitosis, decreased cell adhesion, impaired wound healing

Question 16

does bowman’s layer regenerate

Answer 16

no, will be replaced by epithelial cells or stroma-like fibrous tissue.
very resistant to damage

Question 17

how do new formed connective tissue components in the stroma differ slightly from original tissue

Answer 17

collagen fibers are larger.
alignment and organization of collagen fibers are not as precise

Question 18

does the stroma scar?

Answer 18

yes.
opacification

Question 19

does descemet’s membrane scare if injured

Answer 19

limited regeneration: the size of the injury plays a role… it technically can regenerate because there is an anterior and posterior section, however it does not do well.
a large area of damage will not fully heal.
plus if you damage descemet’s, you definitelyd already have a much larger issue.

Question 20

what secretes and reforms descemet’s membrane

Answer 20

stromal keratocytes and endothelium

Question 21

do endothelial cells regenerate

Answer 21

no

Question 22

what happens to endothelial cell density with age and why

Answer 22

decreases with age because of cell disintegration

Question 23

what happens to the shape of endothelial cells with cell loss

Answer 23

neighboring cells enlarge and flatten to cover the area of loss:
- enlarged endothelial cells
- irregularly shaped cells
- decrease in cell density because they are thinly spread out

Question 24

what happens to water levels when you lose endothelial cells

Answer 24

less H2O channels are present so more water stays in the cell than is leaving the cell –> more water in stroma –> haze