NCLE LATEST 2026 CORE EXAM TEST QUESTIONS AND
SOLUTIONS GRADED A+
✔✔The answer is B.
With regular astigmatism, even high degrees, a soft toric lens can work quite effectively.
Presbyopic and aphakic patients can also be successfully fit with soft lenses. However,
patients with irregular astigmatism will achieve their best visual acuity only with rigid gas
permeable lenses since soft lenses will mold to the corneal contour and not mask the
irregularity. - ✔✔11. In which of the following situations is a rigid gas permeable lens
always preferred over a soft lens?
A. Regular astigmatism
B. Irregular astigmatism
C. Aphakia
D. Presbyopia
✔✔The answer is A.
Decreasing the optical zone diameter while steepening the base curve of a rigid gas
permeable lens will allow the lens to cornea relationship to remain the same, since
decreasing the optical zone diameter loosens the lens to cornea relationship and
steepen- ing the base curve tightens the relationship. Increasing the overall lens
diameter also tightens the fit and will only exaggerate the change made to the lens to
cornea relationship. Decreasing the center thickness or increasing the lens power will
have no significant effect on the relationship of the lens to the cornea. - ✔✔12. In order
to steepen the base curve of a rigid gas permeable lens without changing the lens to
cornea relationship, you would also need to:
A. Decrease the optical zone diameter
B. Decrease the center thickness
C. Increase the overall lens diameter
D. Increase the lens power
✔✔The answer is B.
Increasing the overall lens diameter or increasing the optical zone diameter will steepen
the lens to cornea relationship. Conversely, decreasing the optical zone diameter,
decreasing the overall lens diameter or flattening the base curve will loosen the
relationship. If one change is made that tightens the relationship and another is made
that loosens it, the changes will cancel each other out. - ✔✔13. To steepen the lens to
cornea relationship of a rigid gas permeable lens you could :
A. Increase overall diameter and decrease optical zone diameter
B. Increase overall diameter and increase optical zone diameter
,C. Increase optical zone diameter and decrease overall diameter
D. Increase optical zone diameter and flatten base curve
✔✔The answer is D.
Modification of rigid gas permeable lenses is a valuable skill and can increase a
practitioner's success at RGP fitting. Many in-office modifications can be utilized to
improve the positioning of a lens, reduce discomfort for the patient and eliminate
corneal staining. - ✔✔14. Which is not an indication for modifying a rigid gas permeable
lens?
A. Corneal staining
B. Poor lens position
C. Discomfort
D. Surface Wettability
✔✔The answer is D.
Many modifi~ations to rigid gas permeable lenses can be done in the office, saving time
and improving service. Blending peripheral curves, adding minus power, adding plus
power, polishing the edges, polishing the anterior and posterior surfaces, as well as
reducing lens diameter are all examples of modifications that can be performed in the
office. - ✔✔15. Which of the following modifications can be made to a rigid gas
permeable lens in the office?
A. Blending
B. Changing the power
C. Polishing the edge
D. Changing the base curve
✔✔The answer is A.
Lenses that position temporally or inferiorly are not typically indicated and should be
avoided. Lenses that position superiorly are often lenses that have been designed with
the apical alignment philosophy and have been fit flatter than the flattest keratometer
reading in order to achieve this alignment. Lenses that are fit with apical clearance are
fit steeper than the flattest corneal measurement and often will fit intrapalpebrally or
centrally. - ✔✔16. To achieve a lens to cornea relationship that exhibits apical
clearance, the lens is designed steeper than the flattest corneal measurement. This lens
will most often position:
A. Centrally
B. Temporally
C. Superiorly
D. Inferiorly
,✔✔The answer is C.
The two visual systems utilized by rigid gas permeable bifocals are simultaneous and
alternating. With simultaneous vision systems, both near and far images are received by
the retina at the same time. Concentric and aspheric bifocal lens designs utilize simulta-
neous vision principles. With alternating vision systems, the lens will move on the eye,
delivering the focal length that is in front of the pupil as the lens translates . Segmented
bifocal lens designs fall into this category. - ✔✔17. Which of the following are visual
systems used by rigid gas permeable bifocal lenses?
A. Translating and hyperopic
B. Simultaneous and instantaneous
C. Simultaneous and alternating
D. Truncated and prism ballasted
✔✔The answer is D.
Most translating or alternating rigid gas permeable bifocal lenses must be stabilized in
order for the proper segment to align correctly with the pupil. Two methods of
accomplishing this are by truncating and/ or prism ballasting the lens. In truncation, the
bottom portion of the lens is removed, producing a straight edge that interacts ·with the
lid and aligns the lens in its proper position. With prism ballasting, the bottom portion of
the lens is made thicker than the top portion. Following the same principles as prism
ballasting of a soft toric lens, the thicker portion of the lens will be forced from under the
upper lid to an inferior position. - ✔✔18. Which of the following are methods for
stabilizing the rotation of rigid bifocal contact lenses?
A. Back surface toric and front surface toric
B. Edge roll and polish
C. Alternating and translating
D. Truncation and prism ballast
✔✔The answer is D.
Flattening the base curve of the lens and decreasing the overall diameter will each
decrease the sagittal depth of the contact lens. By combining both factors, the impact
will be magnified. Steepening the base curve and increasing the overall diameter will
both increase the sagittal depth. - ✔✔19. To decrease the sagittal depth of a rigid gas
permeable contact lens you can:
1. Steepen the base curve
2. Flatten the base curve
3. Increasetheoveralldiameter
4. Decrease the overall diameter
A. 1and4
B. 1and3
, C. 2and3
D. 2and4
✔✔The answer is B.
Dimple veil staining is not traditional staining but is rather a pooling of fluorescein in
depressions or "dimples" on the surface of the cornea. These dimples are caused by air
bubbles that become trapped behind a rigid lens in an area where the distance between
the lens and cornea is too great. Dimples will be found centrally if the base curve is too
steep and peripherally if the base curve or peripheral curves are too flat. - ✔✔20.
Dimple veil staining on the cornea is caused by:
A. Poor polishing of peripheral curves
B. Air bubbles trapped under a rigid lens
C. Debris trapped under a rigid lens
D. A cracked contact lens
✔✔The answer is B.
The parameters listed in C and D will flatten the lens to cornea relationship. While
answer A does steepen the lens' relationship, it does not take into account the change
in the power that is necessary when the base curve of the lens is altered. - ✔✔21. The
GP multifocal design that relies on the use of a variable rate of curvature across the
lens surface to achieve a change in power is known as:
A. Concentric
B. Translating
C. Aspheric
D. Truncated
✔✔The answer is B.
"Dk/L" stands for the oxygen transmissibility of a specific lens when manufactured with
a given center thickness. "Dk" stands for the oxygen permeability of the material, but the
actual transmission of oxygen thr ough this material is also dependent on the thickness
of the lens. While the concept of permeability is important to understand, the real impact
is found in the transmissibility of the lens. Wetting angle relates to the ability of tears to
spread on the plastic, specific gravity relates to the weight of the lens material and
neither are related to corneal oxygenation. - ✔✔22. To allow for proper corneal
oxygenation when fitting rigid gas permeable lenses, which of the following material
characteristics must be considered?
A. Dk
B. Dk/t
C. Wetting angle
D. Specific gravity
SOLUTIONS GRADED A+
✔✔The answer is B.
With regular astigmatism, even high degrees, a soft toric lens can work quite effectively.
Presbyopic and aphakic patients can also be successfully fit with soft lenses. However,
patients with irregular astigmatism will achieve their best visual acuity only with rigid gas
permeable lenses since soft lenses will mold to the corneal contour and not mask the
irregularity. - ✔✔11. In which of the following situations is a rigid gas permeable lens
always preferred over a soft lens?
A. Regular astigmatism
B. Irregular astigmatism
C. Aphakia
D. Presbyopia
✔✔The answer is A.
Decreasing the optical zone diameter while steepening the base curve of a rigid gas
permeable lens will allow the lens to cornea relationship to remain the same, since
decreasing the optical zone diameter loosens the lens to cornea relationship and
steepen- ing the base curve tightens the relationship. Increasing the overall lens
diameter also tightens the fit and will only exaggerate the change made to the lens to
cornea relationship. Decreasing the center thickness or increasing the lens power will
have no significant effect on the relationship of the lens to the cornea. - ✔✔12. In order
to steepen the base curve of a rigid gas permeable lens without changing the lens to
cornea relationship, you would also need to:
A. Decrease the optical zone diameter
B. Decrease the center thickness
C. Increase the overall lens diameter
D. Increase the lens power
✔✔The answer is B.
Increasing the overall lens diameter or increasing the optical zone diameter will steepen
the lens to cornea relationship. Conversely, decreasing the optical zone diameter,
decreasing the overall lens diameter or flattening the base curve will loosen the
relationship. If one change is made that tightens the relationship and another is made
that loosens it, the changes will cancel each other out. - ✔✔13. To steepen the lens to
cornea relationship of a rigid gas permeable lens you could :
A. Increase overall diameter and decrease optical zone diameter
B. Increase overall diameter and increase optical zone diameter
,C. Increase optical zone diameter and decrease overall diameter
D. Increase optical zone diameter and flatten base curve
✔✔The answer is D.
Modification of rigid gas permeable lenses is a valuable skill and can increase a
practitioner's success at RGP fitting. Many in-office modifications can be utilized to
improve the positioning of a lens, reduce discomfort for the patient and eliminate
corneal staining. - ✔✔14. Which is not an indication for modifying a rigid gas permeable
lens?
A. Corneal staining
B. Poor lens position
C. Discomfort
D. Surface Wettability
✔✔The answer is D.
Many modifi~ations to rigid gas permeable lenses can be done in the office, saving time
and improving service. Blending peripheral curves, adding minus power, adding plus
power, polishing the edges, polishing the anterior and posterior surfaces, as well as
reducing lens diameter are all examples of modifications that can be performed in the
office. - ✔✔15. Which of the following modifications can be made to a rigid gas
permeable lens in the office?
A. Blending
B. Changing the power
C. Polishing the edge
D. Changing the base curve
✔✔The answer is A.
Lenses that position temporally or inferiorly are not typically indicated and should be
avoided. Lenses that position superiorly are often lenses that have been designed with
the apical alignment philosophy and have been fit flatter than the flattest keratometer
reading in order to achieve this alignment. Lenses that are fit with apical clearance are
fit steeper than the flattest corneal measurement and often will fit intrapalpebrally or
centrally. - ✔✔16. To achieve a lens to cornea relationship that exhibits apical
clearance, the lens is designed steeper than the flattest corneal measurement. This lens
will most often position:
A. Centrally
B. Temporally
C. Superiorly
D. Inferiorly
,✔✔The answer is C.
The two visual systems utilized by rigid gas permeable bifocals are simultaneous and
alternating. With simultaneous vision systems, both near and far images are received by
the retina at the same time. Concentric and aspheric bifocal lens designs utilize simulta-
neous vision principles. With alternating vision systems, the lens will move on the eye,
delivering the focal length that is in front of the pupil as the lens translates . Segmented
bifocal lens designs fall into this category. - ✔✔17. Which of the following are visual
systems used by rigid gas permeable bifocal lenses?
A. Translating and hyperopic
B. Simultaneous and instantaneous
C. Simultaneous and alternating
D. Truncated and prism ballasted
✔✔The answer is D.
Most translating or alternating rigid gas permeable bifocal lenses must be stabilized in
order for the proper segment to align correctly with the pupil. Two methods of
accomplishing this are by truncating and/ or prism ballasting the lens. In truncation, the
bottom portion of the lens is removed, producing a straight edge that interacts ·with the
lid and aligns the lens in its proper position. With prism ballasting, the bottom portion of
the lens is made thicker than the top portion. Following the same principles as prism
ballasting of a soft toric lens, the thicker portion of the lens will be forced from under the
upper lid to an inferior position. - ✔✔18. Which of the following are methods for
stabilizing the rotation of rigid bifocal contact lenses?
A. Back surface toric and front surface toric
B. Edge roll and polish
C. Alternating and translating
D. Truncation and prism ballast
✔✔The answer is D.
Flattening the base curve of the lens and decreasing the overall diameter will each
decrease the sagittal depth of the contact lens. By combining both factors, the impact
will be magnified. Steepening the base curve and increasing the overall diameter will
both increase the sagittal depth. - ✔✔19. To decrease the sagittal depth of a rigid gas
permeable contact lens you can:
1. Steepen the base curve
2. Flatten the base curve
3. Increasetheoveralldiameter
4. Decrease the overall diameter
A. 1and4
B. 1and3
, C. 2and3
D. 2and4
✔✔The answer is B.
Dimple veil staining is not traditional staining but is rather a pooling of fluorescein in
depressions or "dimples" on the surface of the cornea. These dimples are caused by air
bubbles that become trapped behind a rigid lens in an area where the distance between
the lens and cornea is too great. Dimples will be found centrally if the base curve is too
steep and peripherally if the base curve or peripheral curves are too flat. - ✔✔20.
Dimple veil staining on the cornea is caused by:
A. Poor polishing of peripheral curves
B. Air bubbles trapped under a rigid lens
C. Debris trapped under a rigid lens
D. A cracked contact lens
✔✔The answer is B.
The parameters listed in C and D will flatten the lens to cornea relationship. While
answer A does steepen the lens' relationship, it does not take into account the change
in the power that is necessary when the base curve of the lens is altered. - ✔✔21. The
GP multifocal design that relies on the use of a variable rate of curvature across the
lens surface to achieve a change in power is known as:
A. Concentric
B. Translating
C. Aspheric
D. Truncated
✔✔The answer is B.
"Dk/L" stands for the oxygen transmissibility of a specific lens when manufactured with
a given center thickness. "Dk" stands for the oxygen permeability of the material, but the
actual transmission of oxygen thr ough this material is also dependent on the thickness
of the lens. While the concept of permeability is important to understand, the real impact
is found in the transmissibility of the lens. Wetting angle relates to the ability of tears to
spread on the plastic, specific gravity relates to the weight of the lens material and
neither are related to corneal oxygenation. - ✔✔22. To allow for proper corneal
oxygenation when fitting rigid gas permeable lenses, which of the following material
characteristics must be considered?
A. Dk
B. Dk/t
C. Wetting angle
D. Specific gravity
