Lecture 3: 11/16 Flashcards

1
Q

to view corneal abrasions, you use a:

A

slit lamp

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2
Q

what chemical compound do you use during slit lamp exams

A

sodium flurosine

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3
Q

some other qualities of slit lamp

A

magnified view and has a dark blue filter

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4
Q

corneal abrasions usually heal in

A

24-48 hours

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5
Q

2 step process in healing of corneal epithelium

A
  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
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6
Q

what is different about healing of a large abrasion area

A

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

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7
Q

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

A

epithelium

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8
Q

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

A

stroma and bowman’s

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9
Q

what can occur with an abrasion from organic matter?

A

recurrent corneal erosion

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10
Q

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

A

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

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11
Q

3 examples of treatment options for recurrent corneal erosions

A
  • hypertonic drops
  • topical steroids and tetracycline
  • fibronectin
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12
Q

what does fibronectin do

A

wound healing agent, aids in migration of the cells

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13
Q

how common are WBCs in the epithelium?

A

rare

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14
Q

what are infiltrates?

A

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

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15
Q

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

A

basal layer

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16
Q

appearance of the basement membrane under electron microscopy is

A

a thin black line

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17
Q

will the basement membrane heal with or without scar tissue?

A

without

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

18
Q

what type of tissue is the basement membrane made of?

A

a condensation of fine fibrils of connective tissue

19
Q

how thick is bowman’s membrane?

A

12 microns

20
Q

structure of bowman’s membrane

A

modified connective tissue

homogeneous

21
Q

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

A

basement

anterior

22
Q

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

A

stroma

posterior border

23
Q

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

A

for the nerves to pass towards the basal cornea

24
Q

what is special about the repair of bowman’s

A

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

25
the stroma accounts for ___ % of the corneal thickness
90%
26
how thick is the stroma in microns
500 microns
27
edema in the cornea is caused by
swelling of the cornea from the stroma taking up water
28
histology of stroma is
dense regular connective tissue | compact with lots of fibers and few cells
29
histochemically the stroma contains what substances in what percentages
78% water 15% collagen 4.5% micropolysaccarides
30
what types of fibers are in the stroma
collagen
31
what types of cells are found in the stroma?
a type of fibroblast called karatocytes that are modified and flat in the cornea
32
why is it good that the stroma has lots more collagen fibers than cells?
it doesn't present a problem for transparency
33
total number of lamella and layer thickness in the stroma collagen fiber arrangement
200-250 | thickness of 2 microns
34
bands of collagen fibers parallel have a width of
10-20 microns | run from limbus to limbus
35
MPS fiber percentages for sclera and stroma
sclera 1.5% | stroma 4.5%
36
effect of edema on stroma is
disrupt spacins
37
describe descement's membrane layer composition
several layers of compressed filaments of collagen
38
thickness of descemet's membrane at birth versus an adult
birth: 3 microns adult: 12-20 microns
39
Descemet's membrane serves as basement membrane for
endothelium
40
why is Descemet's membrane tough to penetrate?
no elastic fibers