Lecture 2: 11/10

Question 1

what is the groove structure between the junction of the cornea and sclera?

Answer 1

called a sulcus (external and internal parts)

Question 2

what is unique about the external sulcus of the cornea?

Answer 2

can’t see it because that groove is filled over with conjunctiva

Question 3

what important structure is in the inside sulcus of the cornea?

Answer 3

trabecular meshwork

Question 4

what is the trabecular meshwork important for?

Answer 4

for drainage of the fluid in the anterior portion of the eye

Question 5

central cornea thickness

Answer 5

0.50 - 0.70 mm

Question 6

peripheral cornea thickness

Answer 6

0.74 - 1.10 mm

Question 7

average thickness of the cornea

Answer 7

0.56 mm

Question 8

anatomical measurement of cornea is

Answer 8

direct, postmortem on dead cornea

Question 9

physiological measurement of the cornea is

Answer 9

thickness in living human using ultrasonic device

Question 10

which thickness measurement is more representative: anatomical or physiological?

Answer 10

physiological is better because the cornea is functioning and living, post-mortem the cornea starts to swell

Question 11

to measure corneal thickness, what device can be used?

Answer 11

pachometer

Question 12

anterior cornea values for horizontal and vertical diameter

Answer 12

horizontal: 11.7 mm
vertical: 10.6 mm

Question 13

posterior cornea values for horizontal and vertical diameter

Answer 13

horizontal: 11.7 mm
vertical: 11.7 mm

Question 14

3 possible reasons for the elliptical shape of the anterior cornea

Answer 14

1. embryology
2. blinking
3. eyelids

Question 15

what is a micro cornea and what can cause it?

Answer 15

when cornea is smaller than normal and horizontal diameter is less than 11mm
(result of embryology)

Question 16

what is a meglocornea and what can cause it?

Answer 16

when horizontal diameter is greater than 12.5 mm, most likely the result of congenital glaucoma

Question 17

congenital glaucoma is

Answer 17

when you are born with high intraocular pressure, can be caused by ciliary body and iris blocking off trabecular meshwork

Question 18

treatment of congenital glaucoma is

Answer 18

surgery which can take care of anatomical blockage to open trabecular meshwork and allow drainage

Question 19

central anterior radius curvature cornea

Answer 19

7.8 mm

Question 20

posterior radius of curvature cornea

Answer 20

6.5 mm

Question 21

edema of the cornea results in

Answer 21

changes in the anterior radius of curvature because collagen fibers aren’t elastic enough to give and cornea tends to flatten

Question 22

what is the base of cornea anatomical measurement

Answer 22

hypothetical line from one end of the cornea to the other

Question 23

how do you measure the vault of the cornea?

Answer 23

take measurement from base of cornea hypothetical line to anterior surface of the cornea

Question 24

vault value for the cornea is

Answer 24

2.6mm

Question 25

temperature of the cornea is usually

Answer 25

90 degrees

Question 26

why does the cornea have a cooler temperature than the core of the body?

Answer 26

- tear evaporation - it is an external surface - avascular

Question 27

davson experiment results:

Answer 27

corneas in 27C became cloudy, when placed back in 37C, they cleared up again

Question 28

conclusion of the davson experiment

Answer 28

turning down the temperature slowed down metabolism and the cornea swelled and took on water, pumps slowed down, but speed back up with temperature increase

Question 29

the dehydrated state of the cornea is called

Answer 29

deturgescence

Question 30

describe the process of cornea edema

Answer 30

collagen fibers interrupted by the water which disturbs fiber precise arrangement leading to cornea opaqueness from pump slowing

Question 31

3 things that can cause cornea edema

Answer 31

1. oxygen deprivation 2. trauma 3. IOP

Question 32

average IOP values

Answer 32

15-20 mmHg

Question 33

dilated patients can have increased pressure up to what values?

Answer 33

40-50 mmHg

Question 34

2 aspects of the cornea are

Answer 34

central (cornea proper) and limbus (transition zone to sclera)

Question 35

list of the 5 layers of the cornea proper, from anterior to posterior

Answer 35

1. anterior epithelium 2. bowman's membrane 3. stroma 4. descement's membrane 5. endothelium

Question 36

width of the limbus transition zone

Answer 36

1.5-2.0mm wide

Question 37

purpose of the anterior epithelium

Answer 37

to present smooth surface for that refracting element of the eye

Question 38

thickness of the anterior epithelium is

Answer 38

5-6 cells thick

Question 39

histology of the anterior epithelium

Answer 39

- wet - stratified (3 types of cells in this layer) - squamous (anterior surface cells are flat and plate like)

Question 40

list 3 cell types found in anterior epithelium

Answer 40

1. basal cells 2. wing cells 3. surface cells

Question 41

describe the anterior epithelium cell type: basal cells and their attachments

Answer 41

most interior, attached to basement membrane via hemi-desmosomes (not a strong attachment)

Question 42

why is the basal cell layer important?

Answer 42

it is the germinal layer for epithelial cell, highest rate of mitosis in the cornea, cells are formed here and work their way up to the surface

Question 43

wing cells appearance and layer details

Answer 43

cells that are starting to flatten out, contain the next 3 layers of cells

Question 44

apex and base of wing cells are

Answer 44

- convex on top surface | - concave on bottom surface

Question 45

purpose of wing cells

Answer 45

help ad mass to anterior epithelium

Question 46

surface cells have low many cell layers and what kind of histology

Answer 46

1-2 layers | -plate like, squamous, pretty flat and wide

Question 47

surface cells have projections called

Answer 47

microplicae

Question 48

on surface cells, what are the microplicae projections useful for?

Answer 48

thought to have a base for tears to attach and spread out

Question 49

surface cells are attached via

Answer 49

demosomes | a lot stronger

Question 50

whole anterior epithelium of the cornea is how thick?

Answer 50

50-100 microns

Question 51

anterior epithelium represents what percentage of the thickness of the cornea?

Answer 51

10%