NAO FINAL PAPER QUESTIONS AND
ACCURATE ANSWERS COMPLETE
PREPARATION KIT
●● The correct transposition for +2.00 -2.00 x 060 is?
Answer: Plano +2.00 x 150
●● An uncut lens must be at least _______ mm in diameter to allow the
edging of a 54 mm round lens decentered 3 mm in:
Answer: 60 mm
●● A +3.00 sphere lens has a front base curve of +6.25. What is the back
surface curve?
Answer: -3.25
●● A -2.00 -1.00 x 045 lens has a front base curve of +6.25. What are
the back surface curves?
Answer: -8.25 -1.00
●● Moving the optical center of a plus lens inward from the correct PD
results in _____
Answer: Base in prism
,●● Where will the optical center appear in a lensometer when
neutralizing a left lens for base in prism?
Answer: To the left of the target center
●● Glazing is a term used to indicate _____
Answer: A defect that occurs when an anti-reflective lens is tinted
●● Frequently, bicentric grinding (slab-off) is used as a means of
obtaining prism in the reading field to correct induced prism imbalance.
The usual correction during the fabrication process is achieved by
grinding prism in the following direction:
Answer: up
●● A patient stops in to see you for adjustment of his glasses. After
careful inspection you find the only thing wrong that there is too much
pantoscopic tilt. To make the necessary adjustment you will:
Answer: Angle the temples upward from the end pieces
●● If the RX is +2.00 -4.00 x 135, it would be necessary to decenter the
lens _____to create 1.00 prism base in :
Answer: not possible
●● Rewrite the RX below, which is prescribed for a patient afflicted
with double vision, so as to make better balanced lenses:
, OD -1.00 -0.50 x 090 5.00 BU
OS -1.25 - 0.50 x 090 1.00 BD
Answer: OD -1.00 -0.50 x 090 3.00 prism BU
OS -1.25 -0.50x 090 3.00 prism BD
●● Correct the imbalance in the following prescription by use of slab-
off. Reading level is 10 mm:
OD +5.00 -2.00 x 090
OS +2.25 -3.00 x 090
Answer: 2.25 prism BU in OS
●● You are fitting a patient with a stock frame, 24 DBL, 44 eve size and
137 mm skull temples. The distance PD is only 62 mm. If by some
unfortunate error the lenses are not decentered at all, how much prism is
created in each eye?
RX: OU -2.25 -1.50 x 045
Answer: 0.5 prism BI
●● A situation where the frame front is somewhat twisted, with the
planes of the two lenses being out of line with one another, is called:
Answer: Skewed bridge
●● When a frame is said to have a parabolic curve (or positive face
form), the following condition is meant:
ACCURATE ANSWERS COMPLETE
PREPARATION KIT
●● The correct transposition for +2.00 -2.00 x 060 is?
Answer: Plano +2.00 x 150
●● An uncut lens must be at least _______ mm in diameter to allow the
edging of a 54 mm round lens decentered 3 mm in:
Answer: 60 mm
●● A +3.00 sphere lens has a front base curve of +6.25. What is the back
surface curve?
Answer: -3.25
●● A -2.00 -1.00 x 045 lens has a front base curve of +6.25. What are
the back surface curves?
Answer: -8.25 -1.00
●● Moving the optical center of a plus lens inward from the correct PD
results in _____
Answer: Base in prism
,●● Where will the optical center appear in a lensometer when
neutralizing a left lens for base in prism?
Answer: To the left of the target center
●● Glazing is a term used to indicate _____
Answer: A defect that occurs when an anti-reflective lens is tinted
●● Frequently, bicentric grinding (slab-off) is used as a means of
obtaining prism in the reading field to correct induced prism imbalance.
The usual correction during the fabrication process is achieved by
grinding prism in the following direction:
Answer: up
●● A patient stops in to see you for adjustment of his glasses. After
careful inspection you find the only thing wrong that there is too much
pantoscopic tilt. To make the necessary adjustment you will:
Answer: Angle the temples upward from the end pieces
●● If the RX is +2.00 -4.00 x 135, it would be necessary to decenter the
lens _____to create 1.00 prism base in :
Answer: not possible
●● Rewrite the RX below, which is prescribed for a patient afflicted
with double vision, so as to make better balanced lenses:
, OD -1.00 -0.50 x 090 5.00 BU
OS -1.25 - 0.50 x 090 1.00 BD
Answer: OD -1.00 -0.50 x 090 3.00 prism BU
OS -1.25 -0.50x 090 3.00 prism BD
●● Correct the imbalance in the following prescription by use of slab-
off. Reading level is 10 mm:
OD +5.00 -2.00 x 090
OS +2.25 -3.00 x 090
Answer: 2.25 prism BU in OS
●● You are fitting a patient with a stock frame, 24 DBL, 44 eve size and
137 mm skull temples. The distance PD is only 62 mm. If by some
unfortunate error the lenses are not decentered at all, how much prism is
created in each eye?
RX: OU -2.25 -1.50 x 045
Answer: 0.5 prism BI
●● A situation where the frame front is somewhat twisted, with the
planes of the two lenses being out of line with one another, is called:
Answer: Skewed bridge
●● When a frame is said to have a parabolic curve (or positive face
form), the following condition is meant:
