NCLE ADVANCED CERTIFICATION EXAM
QUESTIONS AND ANSWERS ALREADY
PASSED.
• The sagittal depth of a rigid gas permeable contact lens can be altered without
changing thediameter by:
• Changing the power
• Changing the edge design
• Changing the radius of curvature of the anterior optical zone
• Changing the radius of curvature of the posterior optical zone -Answer✅ The
answer is D.
The posterior optical zone will directly affect the lens to cornea relationship of a rigid
gas permeable lens. If the posterior optical zone is steepened, it will increase the sagittal
depth. If itis flattened, it will decrease the sagittal depth. Changing the power, which is
accomplished by changing the anterior optical zone, will not affect the sagittal depth of
the lens, nor will changing its edge design.
• A truncation is used on a rigid gas permeable contact lens to help enhance the
performanceof which type of design?
• Bifocal
• B. Aphakic
• C. Bitoric
D. Keratoconus -Answer✅ The answer is A.
A lens is truncated by removing a segment of the lower edge of a contact lens. This
creates a straight edge that interacts with the lower lid and aids in lens positioning. Of
the lens designs listed in the question, the only one that requires precise positioning of
its optical portions is atranslating bifocal lens.
,• The mass of an aphakic rigid gas permeable contact lens can be reduced by
making the lensdesign:
• Spherical
• B. Lenticular
• C. Tricurve
D. Aspheric -Answer✅ The answer is B.
A lenticular or myoflange design will decrease the mass of an aphakic lens as well as
increase the edge profile, which allows it to interact more with the upper lid and aid in
positioning of thelens.
• In order to tighten the fit of a rigid gas permeable lens you can:I. Increase the
optical zone diameter
• Decrease the optical zone diameter3. Increase the overall lens diameter 4. Use a
prism ballasted lens design
A. 3 only
B. 1&3
C. 2 only
D. 2&3 -Answer✅ The answer is B.
Increasing the optical zone diameter and increasing the overall lens diameter will both
tighten and steepen the relationship of the lens to the cornea. Decreasing the optic zone
diameter will serve to flatten and loosen the lens to cornea relationship. Using a prism-
ballasted lens design will not affect the lens to cornea relationship as it relates to sagittal
depth.
,• A high minus rigid gas permeable lens will be thin centrally with relatively thick
edges. Toreduce the edge thickness, and increase overall comfort, use:
• Aspheric peripheral curves
• A myoflange
• A higher Dk material
• A hyperflange -Answer✅ The answer is D.
A hyperflange will decrease edge thickness as well as lens awareness . Aspheric
peripheral curves change the posterior design of the lens but do not reduce edge
thickness. A higher Dk material will not change the overall lens edge thickness. A
myoflange will actually add thicknessto the lens edge and is used for high plus lenses not
high minus lenses.
• To add minus power to a rigid contact lens with a rotating modifying spindle, one
would:
• Polish the posterior surface of the rigid lensB. Polish the mid peripheral anterior
surface C. Polish the central anterior surface
D. Polish the peripheral anterior surface -Answer✅ The answer is C.
One would rarely polish or attempt to manipulate the central posterior surface of a rigid
lens. Applying polishing pressure to the mid-peripheral and the peripheral anterior
surface would addplus power. Applying polishing pressure to the central anterior surface
would add minus power.
• Which lens design would provide the best visual acuity for a client with the
following information?
K's 42.00@ 180/ 42.50@90Rx -6.75 +1.75 cx 90
• Front surface toric rigid gas permeableB. Spherical rigid gas permeable
C. Soft sphere
, D. Bitoric rigid gas permeable -Answer✅ The answer is A.
The keratometer readings indicate the need for a spherical back surface, which would
rule outthe use of a bitoric lens. A soft spherical lens would not correct the moderate
amount of
refractive astigmatism that is present, nor would the spherical rigid gas permeable lens.
A frontsurface toric RGP would best meet this client's needs since it has a spherical back
surface, but
has a toric front surface which would correct the residual astigmatism.
• Which of the following describes the angle that the edge of a bead of water
makes with thesurface of a plastic?
• Wetting angleB. Surface angle C. Bead angle
D. Reflection angle -Answer✅ The answer is A.
The wetting angle of a rigid gas permeable material describes how a fluid spreads over
the surface. It is important to remember, however, that wetting angle is a description of
the material outside of the client's natural ocular environment. Within minutes of
insertion, a rigidlens is encapsulated in the natural tear mucin and the wetting angle of
the material is no longerimportant.
• If a client has 1.50 D of refractive cylinder and keratometer readings of 44.00@
180/ 44 .50@ 90, a spherical rigid gas permeable lens will:
• Give the client their best correctable visionB. Usually result in residual
astigmatism
C. Fit poorly
D. Be uncomfortable -Answer✅ The answer is B.
The back surface of a rigid lens will usually correct only the astigmatism that is found on
the surface of the cornea. Therefore, when there is significantly more astigmatism in the
refractionthan on the surface of the cornea, residual astigmatism is anticipated.
QUESTIONS AND ANSWERS ALREADY
PASSED.
• The sagittal depth of a rigid gas permeable contact lens can be altered without
changing thediameter by:
• Changing the power
• Changing the edge design
• Changing the radius of curvature of the anterior optical zone
• Changing the radius of curvature of the posterior optical zone -Answer✅ The
answer is D.
The posterior optical zone will directly affect the lens to cornea relationship of a rigid
gas permeable lens. If the posterior optical zone is steepened, it will increase the sagittal
depth. If itis flattened, it will decrease the sagittal depth. Changing the power, which is
accomplished by changing the anterior optical zone, will not affect the sagittal depth of
the lens, nor will changing its edge design.
• A truncation is used on a rigid gas permeable contact lens to help enhance the
performanceof which type of design?
• Bifocal
• B. Aphakic
• C. Bitoric
D. Keratoconus -Answer✅ The answer is A.
A lens is truncated by removing a segment of the lower edge of a contact lens. This
creates a straight edge that interacts with the lower lid and aids in lens positioning. Of
the lens designs listed in the question, the only one that requires precise positioning of
its optical portions is atranslating bifocal lens.
,• The mass of an aphakic rigid gas permeable contact lens can be reduced by
making the lensdesign:
• Spherical
• B. Lenticular
• C. Tricurve
D. Aspheric -Answer✅ The answer is B.
A lenticular or myoflange design will decrease the mass of an aphakic lens as well as
increase the edge profile, which allows it to interact more with the upper lid and aid in
positioning of thelens.
• In order to tighten the fit of a rigid gas permeable lens you can:I. Increase the
optical zone diameter
• Decrease the optical zone diameter3. Increase the overall lens diameter 4. Use a
prism ballasted lens design
A. 3 only
B. 1&3
C. 2 only
D. 2&3 -Answer✅ The answer is B.
Increasing the optical zone diameter and increasing the overall lens diameter will both
tighten and steepen the relationship of the lens to the cornea. Decreasing the optic zone
diameter will serve to flatten and loosen the lens to cornea relationship. Using a prism-
ballasted lens design will not affect the lens to cornea relationship as it relates to sagittal
depth.
,• A high minus rigid gas permeable lens will be thin centrally with relatively thick
edges. Toreduce the edge thickness, and increase overall comfort, use:
• Aspheric peripheral curves
• A myoflange
• A higher Dk material
• A hyperflange -Answer✅ The answer is D.
A hyperflange will decrease edge thickness as well as lens awareness . Aspheric
peripheral curves change the posterior design of the lens but do not reduce edge
thickness. A higher Dk material will not change the overall lens edge thickness. A
myoflange will actually add thicknessto the lens edge and is used for high plus lenses not
high minus lenses.
• To add minus power to a rigid contact lens with a rotating modifying spindle, one
would:
• Polish the posterior surface of the rigid lensB. Polish the mid peripheral anterior
surface C. Polish the central anterior surface
D. Polish the peripheral anterior surface -Answer✅ The answer is C.
One would rarely polish or attempt to manipulate the central posterior surface of a rigid
lens. Applying polishing pressure to the mid-peripheral and the peripheral anterior
surface would addplus power. Applying polishing pressure to the central anterior surface
would add minus power.
• Which lens design would provide the best visual acuity for a client with the
following information?
K's 42.00@ 180/ 42.50@90Rx -6.75 +1.75 cx 90
• Front surface toric rigid gas permeableB. Spherical rigid gas permeable
C. Soft sphere
, D. Bitoric rigid gas permeable -Answer✅ The answer is A.
The keratometer readings indicate the need for a spherical back surface, which would
rule outthe use of a bitoric lens. A soft spherical lens would not correct the moderate
amount of
refractive astigmatism that is present, nor would the spherical rigid gas permeable lens.
A frontsurface toric RGP would best meet this client's needs since it has a spherical back
surface, but
has a toric front surface which would correct the residual astigmatism.
• Which of the following describes the angle that the edge of a bead of water
makes with thesurface of a plastic?
• Wetting angleB. Surface angle C. Bead angle
D. Reflection angle -Answer✅ The answer is A.
The wetting angle of a rigid gas permeable material describes how a fluid spreads over
the surface. It is important to remember, however, that wetting angle is a description of
the material outside of the client's natural ocular environment. Within minutes of
insertion, a rigidlens is encapsulated in the natural tear mucin and the wetting angle of
the material is no longerimportant.
• If a client has 1.50 D of refractive cylinder and keratometer readings of 44.00@
180/ 44 .50@ 90, a spherical rigid gas permeable lens will:
• Give the client their best correctable visionB. Usually result in residual
astigmatism
C. Fit poorly
D. Be uncomfortable -Answer✅ The answer is B.
The back surface of a rigid lens will usually correct only the astigmatism that is found on
the surface of the cornea. Therefore, when there is significantly more astigmatism in the
refractionthan on the surface of the cornea, residual astigmatism is anticipated.
