NCLE MAIN EXAMINATION SET QUESTIONS AND
SOLUTIONS GRADED A+
✔✔The answer is D.
When adding a spherical over-refraction to a bitoric lens, it must be added to both
meridians
Example:
-1.00 / -4.50
-1.00 / -1.00
-2.00 / -5.50 - ✔✔27. Lens specifications in actual drum readings:
43.50/45.50 -1.00/-4.50 9.2 Over-refraction: -1.00 sphere
What is the new lens power?
A. plano/-3.50
B. -1.00/-5.50
C. -2.00/-4.50
D. -2.00/-5.50
✔✔The answer is D.
Decreasing the height of the bifocal segment is the only option that will drop the seg and
alleviate the visual confusion caused by the segment bisecting the pupil. All of the other
options will move the bifocal segment further up into the line of vision. - ✔✔28. A
translating bifocal wearer complains of blur at distance. Upon slit lamp exam, you notice
that the bifocal segment bisects the pupil. In order to improve this situation, you should:
A. Increase the seg height
B. Decrease truncation
C. Decrease prism ballast
D. Decrease seg height
✔✔The answer is B.
Dimple veil staining may occur when there is either a steeper or flatter than
recommended lens to cornea relationship. Air bubbles become trapped in the excessive
space and create dimples on the corneal surface. Antibiotics will not affect dimple veil
staining, nor will lenticulating the edges. Re-evaluating the lens to cornea relationship
will identify the problem and allow the fitter to change the base curve and/ or peripheral
curves to eliminate the dimples. - ✔✔29. Dimple veil staining is resolved by:
1. Antibiotics
2. Steepening the lens to cornea relationship
3. Flattening the lens to cornea relationship
4. Lenticulation
,A. 1 and 2 are correct
B. 2 and 3 are correct
C. 1, 2 and 4 are correct
D. None of the above will resolve dimple veil staining
✔✔The answer is B.
The Rose K, McGuire and Soper lenses are all designs specifically created for the
keratoconus eye, with steeper, smaller optical zone diameters and customized
peripheral curve systems to improve the fit on the unique corneal topography of a
keratoconic eye. - ✔✔30. Rose K, McGuire and Soper are all different types of which
lens design?
A. Post-refractive surgery
B. Keratoconus
C. Torie
D. Aspheric
✔✔The term-28answer is A.
An uncut rigid gas permeable lens has both the posterior and anterior surface cut and
polished. It does not have a peripheral curve system, or a final diameter. The
subsequent steps in lens fabrication would be to reduce the lens to within a 1/ 10 of a
millimeter of its projected finished diameter, apply the posterior peripheral curves, bevel
the front edge and round and taper the edges. - ✔✔31. An uncut rigid gas permeable
contact lens will have the following:
A. Both sides surfaced
B. One side surfaced
C. Semi-finished blank
D. One side molded
✔✔The answer is C.
VascularizedUmbal Keratitis (VLK)is believed to be caused mainly by large diameter
rigid gas permeable lenses with low edge lifts. These lenses chafe the epithelium in the
limbal area in the three and nine o' dock areas, The tear film in the area may also be
altered by this traumatic mechanical effect and has a synergistic effect in causing the
vasogenic response known as VLK. - ✔✔32. Vascularized Limbal Keratitis is usually
caused by:
A. Dry eye syndrome
B. Allergic reaction to solutions
C. Mechanical irritation
D. Excessive exposure to ultraviolet radiation
,✔✔The answer is A.
When comparing wetting angles, the greater the angle, the less hydrophilic is the lens
material. A drop of fluid that creates a 90 degree angle between the drop and the
surface is considered an indication of a hydrophobic surface. When there is an angle of
0, the material is considered completely wet. The smallest wetting angle represents the
most wettable surface, which is most desirable in RGP materials. - ✔✔33. When
comparing wetting angles, which of the following would be the most desirable?
A. 10
B. 20
C. 30
D. 60
✔✔The answer is B.
A drop of fluid that creates an angle of 90 degrees or greater is considered an indication
of a hydrophobic or non-wetting surface. A drop of fluid that creates an angle of 0 to 90
degrees indicates a more wettable material with the lowest values representing the
most wettable surfaces. A drop of fluid that creates an angle of O indicates that the
material is totally hydrophilic. - ✔✔34. The greater the ability of a rigid gas permeable
lens to wet, the ____ the wetting angle?
A. Higher
B. Lower
C. Deeper
D. Rounder
✔✔The answer is C.
Oxygen transmissibility is useful clinically as an indication of oxygen delivery. This is
because it represents the amount of oxygen moving through a specific lens with a given
thickness instead of simply the oxygen moving through a plastic of unknown thickness,
since the oxygen delivery will vary according to the thickness of the lens. - ✔✔35. Dk/t
is:
A. Oxygen Permeability
B. Lens Thickness
C. Oxygen Transmissibility
D. Specific Gravity
✔✔The answer is A.
, Imagine a contact lens as a portion of a sphere. Assuming that the diameter of a lens is
kept constant, if the base curve of a lens is steepened, the distance from the lens
periphery to the imaginary center of the sphere will be shorter. (See diagram) The base
curve of a lens is expressed by the length of its radius. The shorter the radius, the
steeper the curve, conversely the longer radius, the flatter the base curve. Therefore,
when the posterior radius of curvature is decreased, the base curve of the rigid gas
permeable lens is made steeper.
Diameter is constant in each lens, 14mm. The shorter the radius the steeper the lens. -
✔✔36. When the base curve of a rigid gas permeable lens is said to be made steeper, it
means that the posterior radius of curvature is:
A. Decreased
B. Divided
C. Increased
D. Elongated
✔✔The answer is B.
Decreasing edge thickness will allow the lid to re-wet the affected area in the corneal
periphery. A base curve cannot be steepened nor can the diameter of a lens be
increased, either in the lab or in the office and a new lens would have to be ordered if
these changes were required. A diameter gauge is a measuring instrument, not a
modification tool. - ✔✔37. What in-office modification can be performed to alleviate
three and nine o'clock staining?
A. Steepen the base curve with a conical tool
B. Decrease edge thickness with a conical tool
C. Flatten the base curve with a conical tool
D. Increase the diameter with a diameter gauge
✔✔The answer is D.
When a rigid gas permeable lens flexes on the eye, the patient will notice a number of
phenomena. The most obvious is the fluctuation in vision that occurs during the blink.
Continuous flexing of the lens on the eye may also result in a lens that warps over time
and can lead to decreased comfort. - ✔✔38. Higher Dk materials and high minus
prescriptions present a greater chance for the contact lens to flex excessively on the
eye. This may result in which of the following situations?
A. Variable acuity
B. Discomfort
C. Warped central posterior curve D. All of the above
✔✔The answer is C.
SOLUTIONS GRADED A+
✔✔The answer is D.
When adding a spherical over-refraction to a bitoric lens, it must be added to both
meridians
Example:
-1.00 / -4.50
-1.00 / -1.00
-2.00 / -5.50 - ✔✔27. Lens specifications in actual drum readings:
43.50/45.50 -1.00/-4.50 9.2 Over-refraction: -1.00 sphere
What is the new lens power?
A. plano/-3.50
B. -1.00/-5.50
C. -2.00/-4.50
D. -2.00/-5.50
✔✔The answer is D.
Decreasing the height of the bifocal segment is the only option that will drop the seg and
alleviate the visual confusion caused by the segment bisecting the pupil. All of the other
options will move the bifocal segment further up into the line of vision. - ✔✔28. A
translating bifocal wearer complains of blur at distance. Upon slit lamp exam, you notice
that the bifocal segment bisects the pupil. In order to improve this situation, you should:
A. Increase the seg height
B. Decrease truncation
C. Decrease prism ballast
D. Decrease seg height
✔✔The answer is B.
Dimple veil staining may occur when there is either a steeper or flatter than
recommended lens to cornea relationship. Air bubbles become trapped in the excessive
space and create dimples on the corneal surface. Antibiotics will not affect dimple veil
staining, nor will lenticulating the edges. Re-evaluating the lens to cornea relationship
will identify the problem and allow the fitter to change the base curve and/ or peripheral
curves to eliminate the dimples. - ✔✔29. Dimple veil staining is resolved by:
1. Antibiotics
2. Steepening the lens to cornea relationship
3. Flattening the lens to cornea relationship
4. Lenticulation
,A. 1 and 2 are correct
B. 2 and 3 are correct
C. 1, 2 and 4 are correct
D. None of the above will resolve dimple veil staining
✔✔The answer is B.
The Rose K, McGuire and Soper lenses are all designs specifically created for the
keratoconus eye, with steeper, smaller optical zone diameters and customized
peripheral curve systems to improve the fit on the unique corneal topography of a
keratoconic eye. - ✔✔30. Rose K, McGuire and Soper are all different types of which
lens design?
A. Post-refractive surgery
B. Keratoconus
C. Torie
D. Aspheric
✔✔The term-28answer is A.
An uncut rigid gas permeable lens has both the posterior and anterior surface cut and
polished. It does not have a peripheral curve system, or a final diameter. The
subsequent steps in lens fabrication would be to reduce the lens to within a 1/ 10 of a
millimeter of its projected finished diameter, apply the posterior peripheral curves, bevel
the front edge and round and taper the edges. - ✔✔31. An uncut rigid gas permeable
contact lens will have the following:
A. Both sides surfaced
B. One side surfaced
C. Semi-finished blank
D. One side molded
✔✔The answer is C.
VascularizedUmbal Keratitis (VLK)is believed to be caused mainly by large diameter
rigid gas permeable lenses with low edge lifts. These lenses chafe the epithelium in the
limbal area in the three and nine o' dock areas, The tear film in the area may also be
altered by this traumatic mechanical effect and has a synergistic effect in causing the
vasogenic response known as VLK. - ✔✔32. Vascularized Limbal Keratitis is usually
caused by:
A. Dry eye syndrome
B. Allergic reaction to solutions
C. Mechanical irritation
D. Excessive exposure to ultraviolet radiation
,✔✔The answer is A.
When comparing wetting angles, the greater the angle, the less hydrophilic is the lens
material. A drop of fluid that creates a 90 degree angle between the drop and the
surface is considered an indication of a hydrophobic surface. When there is an angle of
0, the material is considered completely wet. The smallest wetting angle represents the
most wettable surface, which is most desirable in RGP materials. - ✔✔33. When
comparing wetting angles, which of the following would be the most desirable?
A. 10
B. 20
C. 30
D. 60
✔✔The answer is B.
A drop of fluid that creates an angle of 90 degrees or greater is considered an indication
of a hydrophobic or non-wetting surface. A drop of fluid that creates an angle of 0 to 90
degrees indicates a more wettable material with the lowest values representing the
most wettable surfaces. A drop of fluid that creates an angle of O indicates that the
material is totally hydrophilic. - ✔✔34. The greater the ability of a rigid gas permeable
lens to wet, the ____ the wetting angle?
A. Higher
B. Lower
C. Deeper
D. Rounder
✔✔The answer is C.
Oxygen transmissibility is useful clinically as an indication of oxygen delivery. This is
because it represents the amount of oxygen moving through a specific lens with a given
thickness instead of simply the oxygen moving through a plastic of unknown thickness,
since the oxygen delivery will vary according to the thickness of the lens. - ✔✔35. Dk/t
is:
A. Oxygen Permeability
B. Lens Thickness
C. Oxygen Transmissibility
D. Specific Gravity
✔✔The answer is A.
, Imagine a contact lens as a portion of a sphere. Assuming that the diameter of a lens is
kept constant, if the base curve of a lens is steepened, the distance from the lens
periphery to the imaginary center of the sphere will be shorter. (See diagram) The base
curve of a lens is expressed by the length of its radius. The shorter the radius, the
steeper the curve, conversely the longer radius, the flatter the base curve. Therefore,
when the posterior radius of curvature is decreased, the base curve of the rigid gas
permeable lens is made steeper.
Diameter is constant in each lens, 14mm. The shorter the radius the steeper the lens. -
✔✔36. When the base curve of a rigid gas permeable lens is said to be made steeper, it
means that the posterior radius of curvature is:
A. Decreased
B. Divided
C. Increased
D. Elongated
✔✔The answer is B.
Decreasing edge thickness will allow the lid to re-wet the affected area in the corneal
periphery. A base curve cannot be steepened nor can the diameter of a lens be
increased, either in the lab or in the office and a new lens would have to be ordered if
these changes were required. A diameter gauge is a measuring instrument, not a
modification tool. - ✔✔37. What in-office modification can be performed to alleviate
three and nine o'clock staining?
A. Steepen the base curve with a conical tool
B. Decrease edge thickness with a conical tool
C. Flatten the base curve with a conical tool
D. Increase the diameter with a diameter gauge
✔✔The answer is D.
When a rigid gas permeable lens flexes on the eye, the patient will notice a number of
phenomena. The most obvious is the fluctuation in vision that occurs during the blink.
Continuous flexing of the lens on the eye may also result in a lens that warps over time
and can lead to decreased comfort. - ✔✔38. Higher Dk materials and high minus
prescriptions present a greater chance for the contact lens to flex excessively on the
eye. This may result in which of the following situations?
A. Variable acuity
B. Discomfort
C. Warped central posterior curve D. All of the above
✔✔The answer is C.
