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NCLE Prep > Q&A > Flashcards

Q&A Flashcards

1
Q

This Test Measures Quality of the Tears

A

B.U.T TEST (Break Up Time)

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2
Q

What is the O2 Permeability

A

DK Value of a lens

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3
Q

What are the Disadvantages of Soft Lenses

A

Doesn’t correct Irregular Astigmatism Favors Deposit formation

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4
Q

For successful contact lens wear, EOP should be at least

A

7%

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5
Q

This test Measures the Quantity of the Tears

A

The Schirmer Test Good result is 15mm in 5 minutes Dry eye is 5 to 10mm in 5 minutes

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6
Q

Neovascularization is mainly due to what

A

Hypoxia, Corneal Edema, Tight Contact lens Fit

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7
Q

The Radii and Power of an average Cornea

A

7.85 mm or +43.00D

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8
Q

What are the Layers of the Cornea

A

Epithelium, Bowmans’ Layer, Stroma, Descemet’s Membrane, Endothelium

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9
Q

The Main Disadvantage of Soft contact lenses

A

Protein Deposits

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10
Q

What is it when we use Contact Lenses to Correct high Myopia

A

Ortho-K

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11
Q

A Contact Lens with diameter that is larger than the Cornea is a Hydrophobic or Hydrophilic

A

Hydrophilic

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12
Q

Which of the following Curves, indicates the flattest Base Curve 7.50mm, 37.50 D, 8.60mm, 49.00 D

A

37.50D

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13
Q

A CTL was ordered with a BC of 7.85mm but was received from the lab with a BC of 7.80mm. The BC of the actual lens is

A

0.25D steeper than the ordered CTL

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14
Q

A CTL with BC of 7.42mm is fitting too loose, a tighter fit may be achieved by changing the base curve to:
7.46mm
7.85mm
8.04mm
None of these

A

None of these…. S.S.S Rule

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15
Q

A CTL has a BC of 7.50mm, what would the PPC most likely be?
7.45mm
42.50D
7.35mm
30.00D

A

30.00D = 11.25mm / S.S.S Rule

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16
Q

What does the Term Haptic Lens refer to?

A

A Scleral CTL Size

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17
Q

The Secondary Curve of a RGP CTL is Generally Flatter or Steeper than the CPC and by How much?

A

Flatter by 2 to 4 Diopters

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18
Q

When the Power of a curve changes by 0.50D , the radius of the Curvature Changes by approximately how much?

A

0.10mm

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19
Q

The CPC of a CTL measures 7.5mm Radius, how much is the Power in Diopters?

A

45.00D

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20
Q

A soft CTL demonstrates excessive movement. This can be fixed with a Lens that has a ______________ Diameter?

A

Larger Diameter. (Larger Diameter = Steeper Fit = Tighter Fit)

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21
Q

HEMA is an Abbreviation commonly used to describe what Lens?

A

the Chemical name for Soft CTL

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22
Q

What is the main reason to utilize a Ballasted CTL?

A

to have less Rotation of the CTL (usually used in bifocal CTL’s)

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23
Q

The Central portion of the Back surface of the CTL is called?

A

CPC (Central Posterior Curve) or the Base Curve (BC) or the Optic Zone

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24
Q

The Distance between a Flat Surface and the Back surface of the Central Portion of a Lens is called the…………….

A

Sagittal Depth ( Vault, height)

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25
Q

A loose fitting CTL can be made to fit tighter by ___________ the Radius of the CPC.

A

Shortening the radius of the CPC. S.S.S Rule

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26
Q

What is an example of a Hydrophilic Lens Material?

A

HEMA

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27
Q

A Contact Lens in which the anterior surface contains 2 different radii of Curvature and the Posterior surface is Spherical curve is called a ……………….

A

Front surface Toric

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28
Q

The Central Portion of a CTL which contains the refractive power of the CTL is the ……

A

OZ

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29
Q

A CTL which contains 2 curves, One BC and One Secondary Curve.

A

Bicurve CTL

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30
Q

The Smoothing of the junction zones by removing the sharp line between the zones is……

A

Blending of the curves

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31
Q

The measurement from one edge of the lens to the opposite edge is……..

A

Chord Diameter

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32
Q

A lens which has been cut off to form a horizontal base which improves stabilization.

A

Truncated Lens

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33
Q

The effective power of a lens when measured from the back surface…

A

BVP - Back Vertex Power

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34
Q

Wetting angle means..

A

the angle that the edge of bead of water makes with the surface of the plastic… the smaller the angle, the greater the wetting ability

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35
Q

A lens in which the anterior surface has two different radii and the posterior surface is spherical….

A

Front Surface Toric Lenses

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36
Q

A Lens in which both the posterior surface has two different radii and the anterior surface has two different radii is……..

A

Bi -Toric

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37
Q

A lens design generally used in higher plus powers which consists of a central optic zone and a surrounding non-optic peripheral or carrier portion is….

A

Lenticular Bowl

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38
Q

A method of manufacturing soft contact lenses whereby a liquid material is revolved in a mold at a controlled speed and temperature which produces the desired curvature, design, and power…….

A

Spin - Cast Lenses

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39
Q

When we add 50% of the Cylinder to the sphere and determine a Spherical Prescription it’s called……

A

Spherical Equivalent (S.E.)

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40
Q

The Tear Film Layers from inside out are….

A

Mucin, Aqueous, Lipid

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41
Q

This Tear Film layer will change the corneal surface from an Hydrophobic surface to a Hydrophilic Surface…..

A

Mucin Layer

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42
Q

The Lipid Layer has a Primary function of…..

A

Preventing Evaporation of the Tears

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43
Q

What age group has the best prognosis for successful Contact Lens Fitting……..

A

13 - 38

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44
Q

When moved 5mm from it’s original position the effective power of a 10.00 D lens will change by………..

A

0.50D

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45
Q

When do we consider vertex distance compensation for Spectacles and for CTL’s?

A

Spectacles 7.00D CTL’S 4.00D

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46
Q

Spectacle Lens is Prescribed at -10.00D, if the lens fit is at a vertex distance of 10mm, an RGP ctl fit on K will require a power of how much?

A

-9.00D minus lens coming closer gains power

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47
Q

RX -4.00+1.00x90 K: 42.50@180/43.50@90 RGP CTL fit on K has a power of………

A

-3.00D

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48
Q

+11.00+1.00x20 VD = 12mm K: 46.25/47.25 What’s the power of RGP lens fitted on K

A

+13.00D +13.25D +13.50D all are correct… NCLE will say +13.00D

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49
Q

-3.00-0.50x90 VD = 11 What’s the RGP CTL power fit 0.50D steeper than the flattest corneal meridian?

A

-3.50D VD doesn’t matter since rx is less than 4.00D

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50
Q

-2.50+0.25x90 VD = 12mm power of CTL if fit 0.75 steeper than K….

A

-3.00D

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51
Q

The CPC of a trial CTL is 44.00D and contains a power equal to +14.87D. The over refraction is equal to -1.62D. What is the Final CTL Rx if the CPC to be ordered is 43.62D….

A

+13.63D (LLP= +0.38D)

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52
Q

A -3.50D Lens with a base curve of 44.50D provides excellent visual acuity. if the CPC were changed to 45.00D what power would be needed?

A

-3.00D (LLP = -0.50D)

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53
Q

A Dry Eye condition can be evaluated with a test called……..

A

Schirmer Test

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54
Q

RX -3.25D-1.00x180 K = 44.25@180 / 45.25@90 Vertex Distance 12mm what is the power of RGP CTL fitting 0.50D Flatter than K

A

-2.75D
2 step question Flat add plus

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55
Q

How do you assess the quality of the peripheral curves of a RGP lens?

A

using a shadowgraph

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56
Q

Patient is wearing a RGP lens in the right eye, it has a power of +3.00D and a base curve of 43.25. if the Dr Refracts -0.50D sphere over this lens and a new lens is to be ordered with a BC of 43.00, what will the new power need to be?

A

+2.75D
2 step question Flat add plus

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57
Q

The optic zone of a RGP lens can be measured with …….

A

Radioscope

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58
Q

An Enzyme contained in the precorneal tear film that protects the cornea from infections is……….

A

Lysozyme

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59
Q

The layer of the precorneal tear film responsible for exchange of materials across the corneal surface is the

A

Aqueous Layer

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60
Q

How many layers does the cornea have?

A

5 layers

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61
Q

The average central thickness of the cornea is…

A

0.56mm

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62
Q

The corneal epithelium obtains oxygen from the..

A

Precorneal Tear Film

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63
Q

The thickest layer of the cornea is the..

A

Stroma

64
Q

The corneal layer primarily responsible for maintaining the Cornea in a partially hydrated state…..

A

Endothelium

65
Q

The Descemet’s membrane of the cornea is produced by which layer of the cornea…..

A

Endothelium

66
Q

Sever damage to the corneal endothelium results in what.

A

Corneal Edema

67
Q

A tightly fitted soft contact lens can cause…….

A

Corneal Edema Limbal Compression

68
Q

The Sclera of the eye is covered by what….

A

Bulbar Conjunctiva

69
Q

New blood vessels that grow into the cornea originate from blood vessels that are located in the?

A

Limbus

70
Q

Obstruction of the flow of aqueous humor out of the anterior chamber results in…

A

Elevated Intra Ocular Pressure (Glaucoma)

71
Q

A condition where the Iris or portions of the Iris in absent is called

A

Aniridia

72
Q

The curvature of the central portion of the back surface of a contact lens is the……

A

Base Curve

73
Q

The central zone of a contact lens that contains the refractive power of the contact lens is the…..

A

Optic Zone

74
Q

The measurement from one edge of a contact lens to the opposite edge is the…..

A

Chord Diameter

75
Q

The base curve of a contact lens is also known as the …..

A

CPC - Central Posterior Curve

76
Q

The Peripheral Posterior Curve of a bicurve Contact Lens is Steeper or Flatter than the CPC

A

Flatter

77
Q

What happens to the sagital vault of the contact lens when a contact lens is steepened…?

A

It increases

78
Q

Shortening the base curve radius of a contact lens makes the lens steeper of flatter?

A

Steeper

79
Q

The problem of a loosely fitting contact lens can be solved by ordering a new contact lens having a ………………….. Base Curve

A

Shorter (SSS)

80
Q

Increasing the overall Diameter of a contact lens makes the lens steeper of flatter?

A

Steeper

81
Q

The Effective power of a contact lens measured from the back surface is the…………

A

Back Vertex Power

82
Q

This Contact lens has 2 different Radii on the anterior surface and a Spheric Posterior curve. It’s used to correct Residual Astigmatism…..

A

Front Toric CL

83
Q

When correcting Large amounts of Corneal Astigmatism a Toric lens must be used that is a …………….. Toric. (Front/Back)

A

Back Toric

84
Q

A contact lens that is used to correct both Corneal and Residual Astigmatism is …………….

A

Bi-Toric

85
Q

A Contact lens with a thickened inferior edge that stabilizes the contact lens is called a…………

A

Prism Ballasted CL

86
Q

A CTL that is Cut off inferiorly so the lower eyelid can help to stabilize the contact lens is called a ………..

A

Truncated CL

87
Q

A CTL that has a low wetting Angle has ………… Wettability

A

Good

88
Q

Decreasing the overall diameter of a CTL will loosen or tighten the fit

A

Loosen the fit

89
Q

A CTL having a BC radius of 7.94 mm fits too loosely, a tighter fitting CTL will have which one of the following BC…. (7.99 / 7.85)

A

7.85mm

90
Q

A CTL having an overall diameter of 9.5mm fits too tightly, a looser ctl will have which diameter……. (9.6 / 9.3)

A

9.3mm

91
Q

An instrument that’s used to measure Corneal Astigmatism is…..

A

Keratometer

92
Q

When the Vertical Corneal meridian is steeper than the Horizontal Corneal Meridian, the corneal astigmatism is……

A

WTR - With the rule

93
Q

Concerning measurements of Corneal Curvatures, the longer the mm of Radius the Larger of Smaller the Diopter value….?

A

Smaller (SSS Rule)

94
Q

A CTL material having a large wetting angle is? Hydrophobic or Hydrophilic?

A

Hydrophobic

95
Q

A Lab Measurement of the Oxygen permeability of a RGP CTL is called……

A

DK Value

96
Q

A measurement of the Oxygen Transmissibility of a RGP CTL is called ……..

A

DK/L

97
Q

The Greater the Central Thickness of a CTL the more or less Oxygen transmissibility?..

A

Less

98
Q

What is EOP?

A

Equivalent Oxygen Performance or Percentage Measures how much Oxygen actually reaches the Cornea while wearing CTL

99
Q

A CTL designed with a peripheral carrier or Flange having no power and a Central Power Zone is called a ……………. CTL

A

Lenticular design

100
Q

Is the Following K reading With the rule or against the rule astigmatism? 43.00@180/44.00@90

A

WTR (More at 90)

101
Q

The K-reading of the horizontal meridian of a cornea is 48.00, this is what mm of radius?

A

7.03mm (337.5 Rule)

102
Q

Vertex Distance must be considered in determining CTL power if the Spectacle Rx is over……………. D

A

+/- 4.00D

103
Q

The BC of a rigid CTL sitting on a cornea is flatter than the corneal curvature. Therefore, the Lacrimal Lens power is……. (plus/Minus)

A

Minus

104
Q

The best type of slit lamp illumination to use for detecting gross corneal edema is called……

A

Sclerotic Scatter

105
Q

The type of slit lamp illumination that is used primarily for a general survey of the external eye is called……

A

Diffuse Illumination

106
Q

The type of slit lamp illumination that is useful for inspecting the anterior surface of a contact lens is called the…….

A

Direct Focal Illumination

107
Q

If a person wanting CTLs has Blepharitis, you should do what?

A

refer them to the prescribing Doctor any type of “ITIS” has to go back to the DR.

108
Q

Where is the Giant Papillary Conjunctivitis Located?….

A

on the Tarsal Plate of the Upper eyelid margin

109
Q

A test used to assess the quality of the precorneal tear film is called the……

A

BUT Test (Break Up Time)

110
Q

Polymegathism of the corneal endothelium is thought to be due to …….

A

Corneal Hypoxia

111
Q

The type of slit lamp illumination used to observe Cells and flare in the anterior chamber of the eye is………

A

Conical Beam Illumination

112
Q

The type of slit lamp illumination that is the method of choice for examination of microcystic epithelial edema of the cornea is called….

A

Retro Illumination

113
Q

The best type of Slit Lamp illumination for studying the corneal endothelium is ……

A

Specular Reflection

114
Q

The Slit lamp light that passes through a cobalt blue filter can be used to observe……….

A

Corneal Staining the Fit of the Contact Lens Corneal Dry spots

115
Q

A Soft CTL case should be thoroughly cleaned at least……..

A

Once per week

116
Q

A Person with Scleral Show requires a (large/small) Diameter soft CTL?

A

large diameter soft CL

117
Q

Preservatives in Contact Lens Solutions can cause ……….

A

Photophobia Corneal Staining Excess Tearing

118
Q

What can occur during an allergic reaction to a CTL solution…..

A

Itching Conjunctival Redness Conjunctival Chemosis (Swelling)

119
Q

True/False Corneal Sensation is reduced in an Aphakic Eye.

A

True

120
Q

Giant Papillary Conjunctivitis occurs more frequently in people who wear what type of lenses….

A

Soft Hydrogel Lenses

121
Q

Wearing standard thickness soft CTL’s longer than 12 hours per day for a prolonged period of time can cause…………

A

An increase in the steepening of the cornea Development of irregular astigmatism Permanent form of acquired Keratoconus

122
Q

Limbal Compression is a sign of (loose - tight) fitted ctl

A

Tightly fitting CTL

123
Q

An eye has a Spectacle Rx of -3.00-0.25X180. This eye should be fit with a soft CTL having a power of…………….

A

-3.00D (1/3 Rule)

124
Q

An eye has a spectacle rx of -3.25-0.50X180. This eye should be fit with a hydrogel CTL having a power of………..

A

-3.25 D (1/3 Rule)

125
Q

An eye has a spectacle Rx of -4.00+1.00X180. this eye should be fit with a hydrogel CTL having a power of………..

A

-3.50 D (1/3 Rule)

126
Q

An eye has a spectacle Rx of -6.50+1.00X090. the K readings are 42.00@180/43.00@90. The Vertex Distance is 12mm. This eye should be fit with Soft CTL RX of

A

-5.25 D (1/3 Rule + 10.10.1 Rule)

127
Q

What are characteristics of PMMA CTL’s……

A

Good Stability Good Optics Acceptable Wettability

128
Q

Which of the following CTL materials has the highest Oxygen Permeability.. (HEMA, PMMA, ACRYLATE, SILICONE)

A

silicone

129
Q

The water content of hydrogel contact lenses varies from……….

A

25% to 85%

130
Q

The higher the Water Content of a Hydrogel CTL the……………….. the Oxygen Transmissibility.

A

Greater

131
Q

Hydrogel CTL are made of what material.

A

HEMA

132
Q

Tears drain into the ………..

A

Punctum

133
Q

During a blink the lower eyelid moves primarily towards the……

A

Nose

134
Q

The Muscle responsible for elevation of the upper eyelid is the……..

A

Levator Palpebrae

135
Q

The PH of the Pre-corneal tear Film is……

A

7.35

136
Q

The layer of the pre corneal tear film that is responsible for exchange of materials across the corneal surface is the……..

A

Aqueous Layer

137
Q

The Function of the Eyelids are………

A

Limit the amount of light entering the eye Protect the eye from external irritation Distribute Tears over the surface of the eye.

138
Q

The opening of the Meibomian glands are found on the……

A

Eyelid Margin

139
Q

The Meibomian Glands are located in the………

A

Tarsal Plate

140
Q

An Acute infection of the Meibomian Glands is called…..

A

an internal hordeolum

141
Q

With spontaneous blinking, the normal blinking rate is……

A

12 - 18 per minute

142
Q

The pre-corneal tear film is composed of how many layers…….

A

3 Lipid, Aqueous, Mucus

143
Q

With basic tear secretion, the aqueous tear film layer is secreted by the…………..

A

Glands of Wolfring and Krause

144
Q

The pre-corneal tear film layer that changes the hydrophobic surface of the cornea to a hydrophilic surface is the …………..

A

Mucous Layer

145
Q

The pre-corneal tear film layer that reduces the rate of tear evaporation is the……….

A

Lipid Layer (oily)

146
Q

The mucous layer of the pre corneal tear film is secreted by the…..

A

Conjunctival Goblet Cells

147
Q

The Lipid Layer of the Precorneal tear film is secreted from………

A

The meibomian glands

148
Q

A spherical PMMA CTL should be fit so that there is a slight……………

A

Apical Clearance

149
Q

When fitting PMMA CTL, the CTL diameter can be calculated by adding 4 mm to the

A

PD

150
Q

A high minus RGP CTL should have ………(+/-) Carrier Lenticular Lenses.

A

Plus Carrier Lenticular Lens. Hyperflange

151
Q

The quality of fit of a RGP CTL can be assessed with the use of……..

A

fluorescein

152
Q

Rigid CTL’s can be modified in the office to become Steeper. (true-False)

A

false

153
Q

What solution improves the wettability of Rigid CTL’s…..

A

wetting solution

154
Q

If a rigid CTL on an eye is too steep the fluorescein pattern will show…….

A

central pooling

155
Q

If a rigid CTL on an eye is too flat the fluorescein pattern will show…….

A

central touch

156
Q

The size of the entire corneal cap can be measured with the….

A

topogometer

NCLE Prep (2 decks)

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