Lecture 4: 11/17

Question 1

2 barrier types presented by the cornea are

Answer 1

lipid and water barriers

Question 2

lipid barrier is found in the cell membranes of what 2 corneal layers

Answer 2

• epithelium

- endothelium

Question 3

water barrier is found in what corneal layer

Answer 3

stroma (78% water)

Question 4

keratitis means

Answer 4

inflammation of the cornea

Question 5

common symptoms of keratitis

Answer 5

pain, photophobia, lacrimation, injection

Question 6

photokeratitis is caused by

Answer 6

overexposure to UV radiation “sunburn of corneal epithelium”

Question 7

common symptoms of photokeratitis

Answer 7

pain or “sandy” feeling, photophobia, lacrimation, and may have blepharospasm (hurts so bad they can’t open eyes)

Question 8

treatment of photokeratitis

Answer 8

will treat itself, painkiller, maybe artificial tears, and follow up to make sure it isn’t infected

Question 9

neovascularization of the cornea is when

Answer 9

there is growth of vessels on to the cornea

Question 10

causes of neovascularization of the cornea

Answer 10

inflammation, irritation, or infection or tight fitting contact lenses

Question 11

why is avoiding neovascularization of the cornea important

Answer 11

for contact lens patients and to reduce the possibility of a corneal graft being needed and rejection

Question 12

what is the limbus?

Answer 12

transition zone between transparent cornea and opaque sclera

Question 13

width of limbus

Answer 13

1.5-2.0 mm wide

Question 14

appearance of limbus and edges

Answer 14

foggy, corneal side is more distinct than the scleral side

Question 15

what are the interdigitations of the limbus

Answer 15

looks like fingers radially around the edge of the cornea and limbus

Question 16

interdigitations of the limbus are called

Answer 16

palisades of Vogt

Question 17

interdigitation upthrusts between waves in the epithelium are called

Answer 17

stromal papilla

Question 18

what is unique about the epithelium between papilla

Answer 18

it is thicker and has a little bit of pigment in it, so it is a little darker

Question 19

list of the 4 definitions of the limbus

Answer 19

1. pathologists
2. histologists
3. anatomical
4. surgical

Question 20

(1) pathologist’s definition of the limbus

Answer 20

• anterior limit: the line from end of bowman’s to end of descemet’s
• posterior limit: 1.5mm posterior, perpendicular to surface (Everything between those limits is the limits)

Question 21

(2) histologist’s definition of the limbus

Answer 21

• interface between cornea and sclera

- junction that starts at the end of bowman’s and is concave line that curves and comes back to the end of descemet’s

Question 22

(3) anatomical definition of the limbus

Answer 22

• anterior limit: the end of bowman’s (corneolimbal junction)
• posterior limit: limboscleral junction

Question 23

anatomical definition of limbus width of anterior and posterior limits

Answer 23

• anterior limit has elliptical shape and is 11.7 mm across

- posterior limit is 1.5mm horizontal and 2.0mm vertical

Question 24

(4) surgical definition of the limbus

Answer 24

peel off (Reflected) conjunctiva, and it is the bluefish zone starting at the edge of the cornea into the sclera

Question 25

both the corneal epithelium and the ____ is stratified epithelium

Answer 25

conjunctiva

Question 26

what 3 corneal layers stop at the limbus?

Answer 26

bowman’s, descement’s, and endothelium

Question 27

what 2 layers of the cornea continue at the limbus

Answer 27

epithelium and stroma

Question 28

epithelium of the cornea becomes the ______ of the conjunctiva

Answer 28

epithelium of the conjunctiva

Question 29

stroma of the cornea becomes what at the limbus

Answer 29

the sclera

Question 30

what are some epithelium changes from cornea to limbus

Answer 30

epithelium of the cornea is smooth and flat, but epithelium of the conjunctiva is bumpy and irregular

Question 31

function of the conjunctiva

Answer 31

protection, so keep bad stuff from getting behind the eye in the orbit, secretion

Question 32

epithelium of the conjunctiva has how many layers?

Answer 32

10-15 layers

Question 33

layers of the epithelium in cornea vs. conjunctiva

Answer 33

in cornea: 5-6 layers

in conjunctiva: 10-15 layers

Question 34

3 types of cells found in the limbus

Answer 34

• fibroblast
• mast cell
• white blood cells (WBCs)

Question 35

what is release from mast cells and why

Answer 35

histamine is released in large quantities when you get an allergic reaction

Question 36

what is a mast cell stabilizer?

Answer 36

it stabilizes the cell membrane so it doesn’t break down and release histamine when you have an allergic reaction
(take about a month or 2 before episode to work)

Question 37

sensory nerves that run into the cornea are derived from what nerve?

Answer 37

5th cranial nerve (V)

trigeminal