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: - ️️up
You are fitting a patient with a stock...
NAO VOLUME 3
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: - ✔️✔️up
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 - ✔️✔️0.5 prism BI
The correct transposition for +2.00 -2.00 x 060 is? - ✔️✔️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: - ✔️✔️60 mm
A +3.00 sphere lens has a front base curve of +6.25. What is the back surface curve? -
✔️✔️-3.25
A -2.00 -1.00 x 045 lens has a front base curve of +6.25. What are the back surface
curves? - ✔️✔️-8.25 -1.00
Moving the optical center of a plus lens inward from the correct PD results in _____ -
✔️✔️Base in prism
The correct transposed RX for -1.00-.50x37 is? - ✔️✔️-1.50 + 0.50 x 127
Where will the optical center appear in a lensometer when neutralizing a left lens for
base in prism? - ✔️✔️To the left of the target center
Glazing is a term used to indicate _____ - ✔️✔️A defect that occurs when an anti-
reflective lens is tinted
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: - ✔️✔️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 : - ✔️✔️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 - ✔️✔️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 - ✔️✔️2.25 prism BU in OS
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: - ✔️✔️Skewed bridge
When a frame is said to have a parabolic curve (or positive face form), the following
condition is meant: - ✔️✔️The bridge of the frame is out further than then end pieces
If the lenses of a patient wearing -8.00 spheres are brought closer or his/her eyes, what
if any effect will this have on the lenses? - ✔️✔️Increase minus power effect
Slab-off is ground on the lens that has the _____in the 090 meridian: - ✔️✔️Weaker
plus
Which of the following areas is not a factor in determining vertical imbalance? -
✔️✔️Add power
A lens dispersing white light into its component colors is an example of : -
✔️✔️Chromatic aberration
The lens aberration that produces a shorter focal length for rays near the edge of the
lens than rays near the optical axis is called: - ✔️✔️Spherical aberration
The aberration affecting image shape when wearing high minus lenses is called: -
✔️✔️barrel distortion
What type of prismatic effect is easiest to tolerate at the near point? - ✔️✔️Base in
You can eliminate the effects of pantoscopic angle by: - ✔️✔️Raising the optical center
by 1/2 the amount of tilt
1 base up ad 2 base in for a left eye would be found in which quadrant? - ✔️✔️II
2 base down and 2 base out for left eye would be found in which quadrant? - ✔️✔️IV
3 base out and 5 base down for a right eye would be found in which quadrant? -
✔️✔️III
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