Sclera

Question 1

Fibroblasts , collagen, proteoglycans are all found in what ?
Cornea/sclera/iris

Answer 1

sclera

Question 2

Scleara has __% of water __% dry weight

A) 70-30
B) 80-20
C)50-80
D)70-10

Answer 2

70-30

Question 3

75% of they dry weight is

(Fibroblasts/collagen/proteoglycans) fiber

Answer 3

collagen

Question 4

Type __ collagen is able to resists tension and is also found in bone and tendon

A) 3
B) 4
C)1
D)5

Answer 4

type 1

Question 5

T/F type 4 collagen is found is the most abundant and is found in bone and tendon

Answer 5

F type 1

Question 6

Like the cornea the sclera is also _______ except for the superficial vessesl fo the episclera and the intracleral vascular plexus

Answer 6

avascular

Question 7

Which two places are exceptions of where there is vascularization in the sclera

Answer 7

episclera,

intrascleral vascular plexus

Question 8

intrascleral vascular plexus is located (posterior/anterior) to the limbus

Answer 8

posterior

Question 9

Overlying the sclera is the _____

Answer 9

episclera

Question 10

The posterior sclera contains the scleral _____ and the _________ for passage of the optic nerve.

Answer 10

canal

lamina cribrosa

Question 11

Passage for the long and short posterior ciliary arteriers , short ciliary veins, ciliary nerves, vortex veins are all perforated sites on the (anterior/posterior) sclera

Answer 11

posterior

Question 12

Tendonsof the recti muslces insert into the (deep/superficial) sclera collagen

Answer 12

superficial

Question 13

T/F 5% of the total surface are of the globe comes from the sclera

Answer 13

F. 95%

Question 14

sclera thickness (increase/decreases) towards the equator and (increases/decreases) near the optic nerve

Answer 14

decreases

increases

Question 15

The mean scleral thickness is ___ at the corneascleral limbus and ____ at the equator

A) 0.40 - 0.39
B) 0.53-0.29
C)0.53-0.39
D)0.40-0.29

Answer 15

0. 53mm

0. 39mm

Question 16

Average scleral fiber ranges from ___to ___ nm

A) 25-400
B) 35-230
C)25-230
D)35-400

Answer 16

25-230

Question 17

Corneal fiber diameter is ___(abnormal/uniform)__ at 25 mm

Answer 17

uniform

Question 18

T/F collagen fibers of the sclera are arranged in bundles , and are parallel

Answer 18

F. corneal fibers are parallel not scleral

scleral fibers only arranged in bundles

Question 19

What are the three distinct fiber types in the sclera fiber system

Answer 19

elastic, elaunin, oxytalan

Question 20

Vision deprivation in a patient can cause axial (elongation/shortness) of teh ocular globe cuasing (myopia/hyperopia)

Answer 20

elongation

myopia

Question 21

Changed in rate of proteoglycan synthesis and accumulation within the sclera can cause (hyperopia/myopia)

Answer 21

myopia

Question 22

With increase in age the sclera undergoes a progressive (regeneration/degeneration) of collagen and elastic fibers
-and a (gain/loss) of GAG
-and scleral (hydration/dehydration)
-and accumulation of which two
(calcium/potassium/lipids/ions)

all of these cause:
(increase/decrease) in tissue density
sclera (thickness/thinning) and yellowing
(decrease/increase) sclera elasticity

Answer 22

degeneration

loss

dehydration

calcium/lipids

increase
thinning
decrease

Question 23

Stroma of the sclera is devoid of ______ however it does allow the passage of ____

Answer 23

innervation

nerves

Question 24

The _(parasympathetic/sympathetic)\_\_ scleral spur cell innervation is present only in cynomolgus monkesy but seems to be absent in humans but 
(parasympathetic/sympathetic) are .

Answer 24

sympathetic

parasympathetic

Question 25

Which type of innervation is absent or rare in both monkeys and humans?

Answer 25

cholinergic innervation

Question 26

Why has there been a resent interest in transcleral delivery of molecules and drugs to potentially treat posterior segment disease??

Answer 26

due to the difficulty reaching therapeutic conecntration of a drug transcorneally

Question 27

T/F intravitreal or intravenous delivery may achieve therapeutic concentration and has no side effects

Answer 27

F. it may have unwanted side effects

Question 28

Transcleral delivery of drugs primary mechansim is diffusion through (lipid/aqueous) pathway?

Answer 28

aqueous

Question 29

Tissue hydration tissue thickness size and volume fraction of proteoglycans present all are controlling ______ rates

Answer 29

diffusion

Question 30

the sclera swells least near a pH of __ A) 3 B) 4 C)1 D)5

Answer 30

4

Question 31

What two functions have been studied that affect the swelling or hydration of the sclera ?

Answer 31

pH and ionic strength

Question 32

Surgical thinning (increases/decreases) sclera permeability

Answer 32

increases

Question 33

Age, cryotherapy, diode laser treatment do NOt alter sclera (rigidity/permeability)

Answer 33

permeability

Question 34

Change of IOP 15 to 60 mm Hg can (increase/decrease) sclera permeability to small molecules by half

Answer 34

decrease

Question 35

scleral permeability is a (weak/strong) funciton of transsceral pressure

Answer 35

weak

Question 36

scleral permeabiliyt is a (weak/strong) funciton of molecular weight

Answer 36

strong

Question 37

with increased molecular weight and radius, scleral permeability (increases/decreases)

Answer 37

decreases

Question 38

When the sclera is exposed to various prostaglandins in organ culture there is (increased/decreased) permeability This causes an (increase/decrease) expression of matrix metalloproteinases

Answer 38

increased increased

Question 39

The (increase/decrease) in sclera permeability may be one mechanism by which prostaglandins (increase/decrease) IOP when used topically.

Answer 39

increase decrease

Question 40

Taking advantage of thinner regions of tisuee Increasing sclera hydration Transient modificatoin of sclera ECM --are all ways for (small/large) molecules to be deliver ______

Answer 40

large transclerally

Question 41

Changd in the ________ parameters of the sclera had rather small effects on teh permability of small compounds , such as conventional drugs

Answer 41

physiochemical