Corneal and Sclera part 2 Flashcards Preview

Ocular Physiology #2 > Corneal and Sclera part 2 > Flashcards

Flashcards in Corneal and Sclera part 2 Deck (161)
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1

what are 2 things that prevent the corneal stroma from swelling

1. the barrier function of the endothelium
2. the pump function of the endothelium

3

what percentage is the water in the corneal stroma maintained at

78%

4

which contributes more to prevent corneal stroma swelling: the epithelium or endothelium border

the epithelium

5

what 4 things occur to the corneal stroma is there is edema

displace the fibrils, increase scatter, halos, and bad vision

6

when the endothelium is disrupted, what is the rate that the cornea swells at

127 microns per hour

7

what happens when the cornea swells

movement of fluid and solutes from the aqueous humor into the stroma, through the incomplete barrier of the intact cell layer, it reaches the max amount and stops

8

if the metabolic pump is disrupted, what is the rate the cornea swells at

33 microns per hour

9

is it normal to have leakage of fluid into the stroma

yes it is a vital function because the cornea is avascular

10

what does the fluid that leaks into the cornea provide

nutrients (glucose and amino acids)

11

what is the maintenance of corneal thickness and water content dependent on

temperature (metabolically energy-dependent process)

12

what happens if the cornea is cooled

it swells

13

what happens if the cornea has a normal temperature

the cornea has normal thickness

14

what is the phenomenon called where temperature affects corneal swelling

temperature reversal

15

how much water is moved by the endothelium from stroma to aqueous humor per hour

6-8 ml

16

where is the Na+K+ATPase pump located in the corneal endothelium

in the basolateral membrane

17

how many Na+K+ATPase pumps are there per cell

1.5 x 10^6

18

what inhibits the N+K+ATPase pumps in the corneal endothelium

Ouabain

19

how does Ouabain inhibit the pumps in corneal endothelium

it stops sodium transport, causes corneal swelling, prevents temperature reversal and eliminates the transendothelial potential difference

20

how is the N+K+ATPase pump affected in corneas with Guttata

increase in pump densities per cell and greater capacity for the pump to counteract the leak

21

what are 2 ocular functions of the Na+K+ATPase pump

1. control of corneal hydration
2. production of aqueous humor

22

why does the corneal stroma readily take up water

to maintain corneal hydration

23

what happens when the sodium ions are transported into channels between endothelial cells

it creates an osmotic pressure and water follows

24

how is the N+K+ATPase pump affected in corneas with inflamed edematous

decreased pump site density despite the increased permeability

25

what 3 things should an ideal intraocular irrigating solution contain

1. energy source- glucose
2. adequate buffer- bicarbonate
3. substrate- calcium, glutathione

26

what aids the sodium ions in the right direction after being pumped

the density of sodium ions in Descemet's membrane

27

what happens in poorly buffered intraocular irrigating solutions

may expose the cornea to pH extremes and cause corneal edema

28

what does normal saline lack

the components of the aqueous humor

29

what is the buffers job in a solution

to maintain the pH

30

what happens with 0.9% NaCl irrigating solution

causes cornea swelling (loss of pump and barrier)

31

what is an ideal intraocular irrigating solution

Glutathione bicarbonate ringers solution GBR