NCLE Prep Exam 3 of 4 Questions
with Complete Solutions23
The tolerance for the overall lens diamter according to the ANSI standards is:
A. +/-0.005mm
B. +/-0.05mm
C. +/-0.01mm
D. +/-0.1mm - ANSWERS-B.
According to the ANSI standards (Z80.2-1989), the tolerance for the overall diameter of a contat
lens is +/-0.05mm. ANSI standards have been developed to maintain quality in the contact lens
industry. It is important to have an understanding of the ANSI guidelines.
All of the following will enable the practitioner to verify the overall rigid gas permeable lens
diameter except:
A. Slot gauge
B. Shadowgraph
C. Measuring magnifer
D. Radiuscope - ANSWERS-D. Radiuscope
The slot gauge, shadowgraph and measuring magnifier will all enable the practitioner to verify
the overall lens diameter of rigid gas permeable lens. The radiuscope is an instrument that will
measure the base curve of a rigid lens.
,Placing the concave side of a rigid gas permeable lens against the lens stop of the lensometer,
will provide you with which of the following?
A. Back vertex power
B. Front vertex power
C. Best vertex power
D. Closest vertex power - ANSWERS-A. Back vertex power
By placing the back (posterior) surface of the rigid gas permeable lens against the lens stop, the
reading that results will be in back vertex power
An instrument that allows simultaneous verification of lens diameter, optic zone width and
peripheral curve width is:
A. Measuring magnifier
B. Ophthalmometer
C. Profile analyzer
D. Radiuscope - ANSWERS-A. Measuring magnifier
An ophthalmometer, another name for the keratometer, cannot measure the listed parameters.
The profile analyzer evaluates the peripheral curve blends and the radiuscope measures the
base curve of the rigid contact lens. The measuring magnifier is the only instrument that will
measure the parameters listed.
Assessment of the quality of the peripheral curves (blends) of a rigid contact lens is achievable
by the use of the:
A. Profile analyzer
, B. Shadowgraph
C. Profile analyzer
D. Burton lamp - ANSWERS-A. Profile analyzer
All of the listed instruments show that a rigid contact lens has blends. However, the only
instrument that can adequately assess the quality of the blends between the peripheral
posterior curve (PPC), intermediate posterior curve (IPC) and the central posterior curve (CPC),
is the profile analyzer.
The instrumental used for magnification of the edge of a rigid contact lens is a:
A. Keratometer
B. Shadowgraph
C. Profile analyzer
D. V-groove gauge - ANSWERS-B. Shadowgraph
A keratometer measures the corneal curvature. A profile analyzer measures the peripheral
curves (blends) and a v-groove gauge measures the diameter of a rigid contact lens.
The tolerance for lens power under +/-10.00D is:
A. 0.12D
B. 0.25D
C. 0.37D
D. 0.50D - ANSWERS-A. 0.12D
According to the ANSI standards (Z80.2 - 1989), the tolerance for the power of a contact lens
under +/-10.00D is +/-0.12D
with Complete Solutions23
The tolerance for the overall lens diamter according to the ANSI standards is:
A. +/-0.005mm
B. +/-0.05mm
C. +/-0.01mm
D. +/-0.1mm - ANSWERS-B.
According to the ANSI standards (Z80.2-1989), the tolerance for the overall diameter of a contat
lens is +/-0.05mm. ANSI standards have been developed to maintain quality in the contact lens
industry. It is important to have an understanding of the ANSI guidelines.
All of the following will enable the practitioner to verify the overall rigid gas permeable lens
diameter except:
A. Slot gauge
B. Shadowgraph
C. Measuring magnifer
D. Radiuscope - ANSWERS-D. Radiuscope
The slot gauge, shadowgraph and measuring magnifier will all enable the practitioner to verify
the overall lens diameter of rigid gas permeable lens. The radiuscope is an instrument that will
measure the base curve of a rigid lens.
,Placing the concave side of a rigid gas permeable lens against the lens stop of the lensometer,
will provide you with which of the following?
A. Back vertex power
B. Front vertex power
C. Best vertex power
D. Closest vertex power - ANSWERS-A. Back vertex power
By placing the back (posterior) surface of the rigid gas permeable lens against the lens stop, the
reading that results will be in back vertex power
An instrument that allows simultaneous verification of lens diameter, optic zone width and
peripheral curve width is:
A. Measuring magnifier
B. Ophthalmometer
C. Profile analyzer
D. Radiuscope - ANSWERS-A. Measuring magnifier
An ophthalmometer, another name for the keratometer, cannot measure the listed parameters.
The profile analyzer evaluates the peripheral curve blends and the radiuscope measures the
base curve of the rigid contact lens. The measuring magnifier is the only instrument that will
measure the parameters listed.
Assessment of the quality of the peripheral curves (blends) of a rigid contact lens is achievable
by the use of the:
A. Profile analyzer
, B. Shadowgraph
C. Profile analyzer
D. Burton lamp - ANSWERS-A. Profile analyzer
All of the listed instruments show that a rigid contact lens has blends. However, the only
instrument that can adequately assess the quality of the blends between the peripheral
posterior curve (PPC), intermediate posterior curve (IPC) and the central posterior curve (CPC),
is the profile analyzer.
The instrumental used for magnification of the edge of a rigid contact lens is a:
A. Keratometer
B. Shadowgraph
C. Profile analyzer
D. V-groove gauge - ANSWERS-B. Shadowgraph
A keratometer measures the corneal curvature. A profile analyzer measures the peripheral
curves (blends) and a v-groove gauge measures the diameter of a rigid contact lens.
The tolerance for lens power under +/-10.00D is:
A. 0.12D
B. 0.25D
C. 0.37D
D. 0.50D - ANSWERS-A. 0.12D
According to the ANSI standards (Z80.2 - 1989), the tolerance for the power of a contact lens
under +/-10.00D is +/-0.12D
