Q&A Flashcards
1
Q
This Test Measures Quality of the Tears
A
B.U.T TEST (Break Up Time)
2
Q
What is the O2 Permeability
A
DK Value of a lens
3
Q
What are the Disadvantages of Soft Lenses
A
Doesn’t correct Irregular Astigmatism Favors Deposit formation
4
Q
For successful contact lens wear, EOP should be at least
A
7%
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
6
Q
Neovascularization is mainly due to what
A
Hypoxia, Corneal Edema, Tight Contact lens Fit
7
Q
The Radii and Power of an average Cornea
A
7.85 mm or +43.00D
8
Q
What are the Layers of the Cornea
A
Epithelium, Bowmans’ Layer, Stroma, Descemet’s Membrane, Endothelium
9
Q
The Main Disadvantage of Soft contact lenses
A
Protein Deposits
10
Q
What is it when we use Contact Lenses to Correct high Myopia
A
Ortho-K
11
Q
A Contact Lens with diameter that is larger than the Cornea is a Hydrophobic or Hydrophilic
A
Hydrophilic
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
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
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
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
16
Q
What does the Term Haptic Lens refer to?
A
A Scleral CTL Size
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
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
19
Q
The CPC of a CTL measures 7.5mm Radius, how much is the Power in Diopters?
A
45.00D
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)
21
Q
HEMA is an Abbreviation commonly used to describe what Lens?
A
the Chemical name for Soft CTL
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)
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
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)
25
A loose fitting CTL can be made to fit tighter by ___________ the Radius of the CPC.
Shortening the radius of the CPC. S.S.S Rule
26
What is an example of a Hydrophilic Lens Material?
HEMA
27
A Contact Lens in which the anterior surface contains 2 different radii of Curvature and the Posterior surface is Spherical curve is called a ...................
Front surface Toric
28
The Central Portion of a CTL which contains the refractive power of the CTL is the ......
OZ
29
A CTL which contains 2 curves, One BC and One Secondary Curve.
Bicurve CTL
30
The Smoothing of the junction zones by removing the sharp line between the zones is......
Blending of the curves
31
The measurement from one edge of the lens to the opposite edge is........
Chord Diameter
32
A lens which has been cut off to form a horizontal base which improves stabilization.
Truncated Lens
33
The effective power of a lens when measured from the back surface...
BVP - Back Vertex Power
34
Wetting angle means..
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
35
A lens in which the anterior surface has two different radii and the posterior surface is spherical....
Front Surface Toric Lenses
36
A Lens in which both the posterior surface has two different radii and the anterior surface has two different radii is........
Bi -Toric
37
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....
Lenticular Bowl
38
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.......
Spin - Cast Lenses
39
When we add 50% of the Cylinder to the sphere and determine a Spherical Prescription it's called......
Spherical Equivalent (S.E.)
40
The Tear Film Layers from inside out are....
Mucin, Aqueous, Lipid
41
This Tear Film layer will change the corneal surface from an Hydrophobic surface to a Hydrophilic Surface.....
Mucin Layer
42
The Lipid Layer has a Primary function of.....
Preventing Evaporation of the Tears
43
What age group has the best prognosis for successful Contact Lens Fitting........
13 - 38
44
When moved 5mm from it's original position the effective power of a 10.00 D lens will change by...........
0.50D
45
When do we consider vertex distance compensation for Spectacles and for CTL's?
Spectacles 7.00D CTL'S 4.00D
46
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?
-9.00D minus lens coming closer gains power
47
RX -4.00+1.00x90 K: 42.50@180/43.50@90 RGP CTL fit on K has a power of.........
-3.00D
48
+11.00+1.00x20 VD = 12mm K: 46.25/47.25 What's the power of RGP lens fitted on K
+13.00D +13.25D +13.50D all are correct... NCLE will say +13.00D
49
-3.00-0.50x90 VD = 11 What's the RGP CTL power fit 0.50D steeper than the flattest corneal meridian?
-3.50D VD doesn't matter since rx is less than 4.00D
50
-2.50+0.25x90 VD = 12mm power of CTL if fit 0.75 steeper than K....
-3.00D
51
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....
+13.63D (LLP= +0.38D)
52
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?
-3.00D (LLP = -0.50D)
53
A Dry Eye condition can be evaluated with a test called........
Schirmer Test
54
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
-2.75D
2 step question Flat add plus
55
How do you assess the quality of the peripheral curves of a RGP lens?
using a shadowgraph
56
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?
+2.75D
2 step question Flat add plus
57
The optic zone of a RGP lens can be measured with .......
Radioscope
58
An Enzyme contained in the precorneal tear film that protects the cornea from infections is..........
Lysozyme
59
The layer of the precorneal tear film responsible for exchange of materials across the corneal surface is the
Aqueous Layer
60
How many layers does the cornea have?
5 layers
61
The average central thickness of the cornea is...
0.56mm
62
The corneal epithelium obtains oxygen from the..
Precorneal Tear Film
63
The thickest layer of the cornea is the..
Stroma
64
The corneal layer primarily responsible for maintaining the Cornea in a partially hydrated state.....
Endothelium
65
The Descemet's membrane of the cornea is produced by which layer of the cornea.....
Endothelium
66
Sever damage to the corneal endothelium results in what.
Corneal Edema
67
A tightly fitted soft contact lens can cause.......
Corneal Edema Limbal Compression
68
The Sclera of the eye is covered by what....
Bulbar Conjunctiva
69
New blood vessels that grow into the cornea originate from blood vessels that are located in the?
Limbus
70
Obstruction of the flow of aqueous humor out of the anterior chamber results in...
Elevated Intra Ocular Pressure (Glaucoma)
71
A condition where the Iris or portions of the Iris in absent is called
Aniridia
72
The curvature of the central portion of the back surface of a contact lens is the......
Base Curve
73
The central zone of a contact lens that contains the refractive power of the contact lens is the.....
Optic Zone
74
The measurement from one edge of a contact lens to the opposite edge is the.....
Chord Diameter
75
The base curve of a contact lens is also known as the .....
CPC - Central Posterior Curve
76
The Peripheral Posterior Curve of a bicurve Contact Lens is Steeper or Flatter than the CPC
Flatter
77
What happens to the sagital vault of the contact lens when a contact lens is steepened...?
It increases
78
Shortening the base curve radius of a contact lens makes the lens steeper of flatter?
Steeper
79
The problem of a loosely fitting contact lens can be solved by ordering a new contact lens having a ....................... Base Curve
Shorter (SSS)
80
Increasing the overall Diameter of a contact lens makes the lens steeper of flatter?
Steeper
81
The Effective power of a contact lens measured from the back surface is the............
Back Vertex Power
82
This Contact lens has 2 different Radii on the anterior surface and a Spheric Posterior curve. It's used to correct Residual Astigmatism.....
Front Toric CL
83
When correcting Large amounts of Corneal Astigmatism a Toric lens must be used that is a ................. Toric. (Front/Back)
Back Toric
84
A contact lens that is used to correct both Corneal and Residual Astigmatism is ................
Bi-Toric
85
A Contact lens with a thickened inferior edge that stabilizes the contact lens is called a............
Prism Ballasted CL
86
A CTL that is Cut off inferiorly so the lower eyelid can help to stabilize the contact lens is called a ...........
Truncated CL
87
A CTL that has a low wetting Angle has ............ Wettability
Good
88
Decreasing the overall diameter of a CTL will loosen or tighten the fit
Loosen the fit
89
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)
7.85mm
90
A CTL having an overall diameter of 9.5mm fits too tightly, a looser ctl will have which diameter....... (9.6 / 9.3)
9.3mm
91
An instrument that's used to measure Corneal Astigmatism is.....
Keratometer
92
When the Vertical Corneal meridian is steeper than the Horizontal Corneal Meridian, the corneal astigmatism is......
WTR - With the rule
93
Concerning measurements of Corneal Curvatures, the longer the mm of Radius the Larger of Smaller the Diopter value....?
Smaller (SSS Rule)
94
A CTL material having a large wetting angle is? Hydrophobic or Hydrophilic?
Hydrophobic
95
A Lab Measurement of the Oxygen permeability of a RGP CTL is called......
DK Value
96
A measurement of the Oxygen Transmissibility of a RGP CTL is called ........
DK/L
97
The Greater the Central Thickness of a CTL the more or less Oxygen transmissibility?..
Less
98
What is EOP?
Equivalent Oxygen Performance or Percentage Measures how much Oxygen actually reaches the Cornea while wearing CTL
99
A CTL designed with a peripheral carrier or Flange having no power and a Central Power Zone is called a ................ CTL
Lenticular design
100
Is the Following K reading With the rule or against the rule astigmatism? 43.00@180/44.00@90
WTR (More at 90)
101
The K-reading of the horizontal meridian of a cornea is 48.00, this is what mm of radius?
7.03mm (337.5 Rule)
102
Vertex Distance must be considered in determining CTL power if the Spectacle Rx is over................ D
+/- 4.00D
103
The BC of a rigid CTL sitting on a cornea is flatter than the corneal curvature. Therefore, the Lacrimal Lens power is....... (plus/Minus)
Minus
104
The best type of slit lamp illumination to use for detecting gross corneal edema is called......
Sclerotic Scatter
105
The type of slit lamp illumination that is used primarily for a general survey of the external eye is called......
Diffuse Illumination
106
The type of slit lamp illumination that is useful for inspecting the anterior surface of a contact lens is called the.......
Direct Focal Illumination
107
If a person wanting CTLs has Blepharitis, you should do what?
refer them to the prescribing Doctor any type of "ITIS" has to go back to the DR.
108
Where is the Giant Papillary Conjunctivitis Located?....
on the Tarsal Plate of the Upper eyelid margin
109
A test used to assess the quality of the precorneal tear film is called the......
BUT Test (Break Up Time)
110
Polymegathism of the corneal endothelium is thought to be due to .......
Corneal Hypoxia
111
The type of slit lamp illumination used to observe Cells and flare in the anterior chamber of the eye is.........
Conical Beam Illumination
112
The type of slit lamp illumination that is the method of choice for examination of microcystic epithelial edema of the cornea is called....
Retro Illumination
113
The best type of Slit Lamp illumination for studying the corneal endothelium is ......
Specular Reflection
114
The Slit lamp light that passes through a cobalt blue filter can be used to observe..........
Corneal Staining the Fit of the Contact Lens Corneal Dry spots
115
A Soft CTL case should be thoroughly cleaned at least........
Once per week
116
A Person with Scleral Show requires a (large/small) Diameter soft CTL?
large diameter soft CL
117
Preservatives in Contact Lens Solutions can cause ..........
Photophobia Corneal Staining Excess Tearing
118
What can occur during an allergic reaction to a CTL solution.....
Itching Conjunctival Redness Conjunctival Chemosis (Swelling)
119
True/False Corneal Sensation is reduced in an Aphakic Eye.
True
120
Giant Papillary Conjunctivitis occurs more frequently in people who wear what type of lenses....
Soft Hydrogel Lenses
121
Wearing standard thickness soft CTL's longer than 12 hours per day for a prolonged period of time can cause............
An increase in the steepening of the cornea Development of irregular astigmatism Permanent form of acquired Keratoconus
122
Limbal Compression is a sign of (loose - tight) fitted ctl
Tightly fitting CTL
123
An eye has a Spectacle Rx of -3.00-0.25X180. This eye should be fit with a soft CTL having a power of................
-3.00D (1/3 Rule)
124
An eye has a spectacle rx of -3.25-0.50X180. This eye should be fit with a hydrogel CTL having a power of...........
-3.25 D (1/3 Rule)
125
An eye has a spectacle Rx of -4.00+1.00X180. this eye should be fit with a hydrogel CTL having a power of...........
-3.50 D (1/3 Rule)
126
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
-5.25 D (1/3 Rule + 10.10.1 Rule)
127
What are characteristics of PMMA CTL's......
Good Stability Good Optics Acceptable Wettability
128
Which of the following CTL materials has the highest Oxygen Permeability.. (HEMA, PMMA, ACRYLATE, SILICONE)
silicone
129
The water content of hydrogel contact lenses varies from..........
25% to 85%
130
The higher the Water Content of a Hydrogel CTL the.................... the Oxygen Transmissibility.
Greater
131
Hydrogel CTL are made of what material.
HEMA
132
Tears drain into the ...........
Punctum
133
During a blink the lower eyelid moves primarily towards the......
Nose
134
The Muscle responsible for elevation of the upper eyelid is the........
Levator Palpebrae
135
The PH of the Pre-corneal tear Film is......
7.35
136
The layer of the pre corneal tear film that is responsible for exchange of materials across the corneal surface is the........
Aqueous Layer
137
The Function of the Eyelids are.........
Limit the amount of light entering the eye Protect the eye from external irritation Distribute Tears over the surface of the eye.
138
The opening of the Meibomian glands are found on the......
Eyelid Margin
139
The Meibomian Glands are located in the.........
Tarsal Plate
140
An Acute infection of the Meibomian Glands is called.....
an internal hordeolum
141
With spontaneous blinking, the normal blinking rate is......
12 - 18 per minute
142
The pre-corneal tear film is composed of how many layers.......
3 Lipid, Aqueous, Mucus
143
With basic tear secretion, the aqueous tear film layer is secreted by the..............
Glands of Wolfring and Krause
144
The pre-corneal tear film layer that changes the hydrophobic surface of the cornea to a hydrophilic surface is the ..............
Mucous Layer
145
The pre-corneal tear film layer that reduces the rate of tear evaporation is the..........
Lipid Layer (oily)
146
The mucous layer of the pre corneal tear film is secreted by the.....
Conjunctival Goblet Cells
147
The Lipid Layer of the Precorneal tear film is secreted from.........
The meibomian glands
148
A spherical PMMA CTL should be fit so that there is a slight...............
Apical Clearance
149
When fitting PMMA CTL, the CTL diameter can be calculated by adding 4 mm to the
PD
150
A high minus RGP CTL should have .........(+/-) Carrier Lenticular Lenses.
Plus Carrier Lenticular Lens. Hyperflange
151
The quality of fit of a RGP CTL can be assessed with the use of........
fluorescein
152
Rigid CTL's can be modified in the office to become Steeper. (true-False)
false
153
What solution improves the wettability of Rigid CTL's.....
wetting solution
154
If a rigid CTL on an eye is too steep the fluorescein pattern will show.......
central pooling
155
If a rigid CTL on an eye is too flat the fluorescein pattern will show.......
central touch
156
The size of the entire corneal cap can be measured with the....
topogometer
