Lecture 3: 11/16

Question 1

to view corneal abrasions, you use a:

Answer 1

slit lamp

Question 2

what chemical compound do you use during slit lamp exams

Answer 2

sodium flurosine

Question 3

some other qualities of slit lamp

Answer 3

magnified view and has a dark blue filter

Question 4

corneal abrasions usually heal in

Answer 4

24-48 hours

Question 5

2 step process in healing of corneal epithelium

Answer 5

1. migration of cells on either side of the abrasion to the hole or scratch
2. rapid mitosis, basal cells undergoing mitosis to make new cells that eventually make it to the surface

Question 6

what is different about healing of a large abrasion area

Answer 6

primary means of repair is mitosis, and it can take about a week for the cells to regenerate and then migrate up to surface

Question 7

there is no scar tissue after healing of damage if on what layer of the cornea

Answer 7

epithelium

Question 8

there is scar tissue after healing of damage on what layers of the cornea

Answer 8

stroma and bowman’s

Question 9

what can occur with an abrasion from organic matter?

Answer 9

recurrent corneal erosion

Question 10

what is a recurrent corneal erosion and what does it cause?

Answer 10

it interferes with basal cells sticking on to basal membranes (hemi-desmosomes) and corneal abrasions will recurrently “rip off” the cornea

Question 11

3 examples of treatment options for recurrent corneal erosions

Answer 11

• hypertonic drops
• topical steroids and tetracycline
• fibronectin

Question 12

what does fibronectin do

Answer 12

wound healing agent, aids in migration of the cells

Question 13

how common are WBCs in the epithelium?

Answer 13

rare

Question 14

what are infiltrates?

Answer 14

when a large number of macrophages go to site of infection and form white spots on the cornea

Question 15

if WBCs and infiltrates are found in the epithelium, in which layer would they be in?

Answer 15

basal layer

Question 16

appearance of the basement membrane under electron microscopy is

Answer 16

a thin black line

Question 17

will the basement membrane heal with or without scar tissue?

Answer 17

without

but it is so thin it is hard not to also damage the layers underneath it

Question 18

what type of tissue is the basement membrane made of?

Answer 18

a condensation of fine fibrils of connective tissue

Question 19

how thick is bowman’s membrane?

Answer 19

12 microns

Question 20

structure of bowman’s membrane

Answer 20

modified connective tissue

homogeneous

Question 21

the border of bowman’s against the _____ membrane is distinct

Answer 21

basement

anterior

Question 22

the border of bowman’s against the ______ membrane is not as distinct

Answer 22

stroma

posterior border

Question 23

in bowman’s membrane, pores are found and serve what purpose

Answer 23

for the nerves to pass towards the basal cornea

Question 24

what is special about the repair of bowman’s

Answer 24

it doesn’t regenerate as original tissue, it regenerates as fibrous tissue if damaged (Scar)

Question 25

the stroma accounts for ___ % of the corneal thickness

Answer 25

90%

Question 26

how thick is the stroma in microns

Answer 26

500 microns

Question 27

edema in the cornea is caused by

Answer 27

swelling of the cornea from the stroma taking up water

Question 28

histology of stroma is

Answer 28

dense regular connective tissue

compact with lots of fibers and few cells

Question 29

histochemically the stroma contains what substances in what percentages

Answer 29

78% water
15% collagen
4.5% micropolysaccarides

Question 30

what types of fibers are in the stroma

Answer 30

collagen

Question 31

what types of cells are found in the stroma?

Answer 31

a type of fibroblast called karatocytes that are modified and flat in the cornea

Question 32

why is it good that the stroma has lots more collagen fibers than cells?

Answer 32

it doesn’t present a problem for transparency

Question 33

total number of lamella and layer thickness in the stroma collagen fiber arrangement

Answer 33

200-250

thickness of 2 microns

Question 34

bands of collagen fibers parallel have a width of

Answer 34

10-20 microns

run from limbus to limbus

Question 35

MPS fiber percentages for sclera and stroma

Answer 35

sclera 1.5%

stroma 4.5%

Question 36

effect of edema on stroma is

Answer 36

disrupt spacins

Question 37

describe descement’s membrane layer composition

Answer 37

several layers of compressed filaments of collagen

Question 38

thickness of descemet’s membrane at birth versus an adult

Answer 38

birth: 3 microns
adult: 12-20 microns

Question 39

Descemet’s membrane serves as basement membrane for

Answer 39

endothelium

Question 40

why is Descemet’s membrane tough to penetrate?

Answer 40

no elastic fibers