March 25
NAO VOLUME 3 Complete Questions and Correct Detailed
Answers (Verified Answers)
The correct transposed RX for -1.00-.50x37 is?
Ans: -1.50 + 0.50 x 127
The correct transposition for +2.00 -2.00 x 060 is?
Ans: 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:
Ans: 60 mm
A +3.00 sphere lens has a front base curve of +6.25. What is the back surface curve?
Ans: -3.25
A -2.00 -1.00 x 045 lens has a front base curve of +6.25. What are the back surface
curves?
Ans: -8.25 -1.00
Moving the optical center of a plus lens inward from the correct PD results in _____
pg. 1
, March 25
Ans: Base in prism
Where will the optical center appear in a lensometer when neutralizing a left lens for
base in prism?
Ans: To the left of the target center
Glazing is a term used to indicate _____
Ans: 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:
Ans: 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:
Ans: 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 :
pg. 2
, March 25
Ans: 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
Ans: 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
Ans: 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
Ans: 0.5 prism BI
pg. 3
NAO VOLUME 3 Complete Questions and Correct Detailed
Answers (Verified Answers)
The correct transposed RX for -1.00-.50x37 is?
Ans: -1.50 + 0.50 x 127
The correct transposition for +2.00 -2.00 x 060 is?
Ans: 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:
Ans: 60 mm
A +3.00 sphere lens has a front base curve of +6.25. What is the back surface curve?
Ans: -3.25
A -2.00 -1.00 x 045 lens has a front base curve of +6.25. What are the back surface
curves?
Ans: -8.25 -1.00
Moving the optical center of a plus lens inward from the correct PD results in _____
pg. 1
, March 25
Ans: Base in prism
Where will the optical center appear in a lensometer when neutralizing a left lens for
base in prism?
Ans: To the left of the target center
Glazing is a term used to indicate _____
Ans: 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:
Ans: 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:
Ans: 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 :
pg. 2
, March 25
Ans: 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
Ans: 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
Ans: 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
Ans: 0.5 prism BI
pg. 3
