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OCULAR PHYSIOLOGY > Sclera > Flashcards

Sclera Flashcards

1
Q

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

A

sclera

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2
Q

Scleara has __% of water __% dry weight

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

A

70-30

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3
Q

75% of they dry weight is

(Fibroblasts/collagen/proteoglycans) fiber

A

collagen

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4
Q

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

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

A

type 1

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5
Q

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

A

F type 1

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6
Q

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

A

avascular

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7
Q

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

A

episclera,

intrascleral vascular plexus

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8
Q

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

A

posterior

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9
Q

Overlying the sclera is the _____

A

episclera

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10
Q

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

A

canal

lamina cribrosa

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11
Q

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

A

posterior

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12
Q

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

A

superficial

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13
Q

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

A

F. 95%

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14
Q

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

A

decreases

increases

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15
Q

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

A
  1. 53mm

0. 39mm

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16
Q

Average scleral fiber ranges from ___to ___ nm

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

A

25-230

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17
Q

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

A

uniform

18
Q

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

A

F. corneal fibers are parallel not scleral

scleral fibers only arranged in bundles

19
Q

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

A

elastic, elaunin, oxytalan

20
Q

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

A

elongation

myopia

21
Q

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

A

myopia

22
Q 
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

A

degeneration

loss

dehydration

calcium/lipids

increase
thinning
decrease

23
Q

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

A

innervation

nerves

24
Q 
The _(parasympathetic/sympathetic)\_\_ scleral spur cell innervation is present only in cynomolgus monkesy but seems to be absent in humans but 
(parasympathetic/sympathetic) are .
A

sympathetic

parasympathetic

25
Q

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

A

cholinergic innervation

26
Q

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

A

due to the difficulty reaching therapeutic conecntration of a drug transcorneally

27
Q

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

A

F. it may have unwanted side effects

28
Q

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

A

aqueous

29
Q

Tissue hydration
tissue thickness
size and volume fraction of proteoglycans present

all are controlling ______ rates

A

diffusion

30
Q

the sclera swells least near a pH of __

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

A

4

31
Q

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

A

pH and ionic strength

32
Q

Surgical thinning (increases/decreases) sclera permeability

A

increases

33
Q

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

A

permeability

34
Q

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

A

decrease

35
Q

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

A

weak

36
Q

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

A

strong

37
Q

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

A

decreases

38
Q

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

A

increased

increased

39
Q

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

A

increase

decrease

40
Q

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 ______

A

large

transclerally

41
Q

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

A

physiochemical

OCULAR PHYSIOLOGY (13 decks)

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