Exam (elaborations)
ABO Practice Test questions and answers
ABO Practice Test questions and answers
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ABO Practice Test questions and answersWhen discussing thick lenses, the factors which are considered in computing the
lens power are:
a. front curve, thickness and index
b. back curve, thickness and index
c. front curve, back curve and thickness
d. front curve, back curve, thickness and index - CORRECT ANSWER-d. front
curve, back curve, thickness and index
Toric transposition shows:
a. lens thickness
b. power in principal meridians
c. the power of the ADD
d. the lens diameter - CORRECT ANSWER-b. power in principal meridians
Increasing the diameter of a minus power lens always increases its:
a. vertex power
b. center thickness
c. weight
d. refractive index - CORRECT ANSWER-c. weight
The optical center of a round segment is located:
a. at the very top of the segment
b. in the geometric center of the segment
c. 5 mm from the top of the segment
d. at the very bottom of the segment - CORRECT ANSWER-b. in the geometric
center of the segment
The base curve of any multifocal lens is found on the surface containing the:
a. cross curve
,b. cylinder surface
c. segment
d. ocular curve - CORRECT ANSWER-c. segment
Normal slab-off (bicentric grind) is ground on the lens whose vertical meridian
has the:
a. strongest curves
b. most plus power
c. least plus power
d. least minus power - CORRECT ANSWER-c. least plus power
The refractive error indicated by the Rx +1.75 -2.75 x 090 is:
a. compound hyperopic astigmatism
b. compound myopic astigmatism
c. simple myopic astigmatism
d. mixed astigmatism - CORRECT ANSWER-d. mixed astigmatism
Tempering a lens by heat treating results in a lens being:
a. less resistant to impact
b. more resistant to impact
c. more resistant to surface scratching
d. impossible to break - CORRECT ANSWER-b. more resistant to impact
A slab-off lens is for the correction of:
a. astigmatic errors
b. excessive weight of lens
c. excessive prism imbalance at the reading level
d. exotropia - CORRECT ANSWER-c. excessive prism imbalance at the reading
level
Chem-tempering makes a glass lens more impact resistant by placing the lens in
a potassium nitrate bath. The lens undergoes a process known as:
,a. ion exchange
b. iron oxide activation
c. silver halide transfer
d. thermal bleaching - CORRECT ANSWER-a. ion exchange
Which wavelengths of light have been indicated as possible contributors to the
onset of cataracts?
a. 400-520 nm
b. 520-635 nm
c. 350-400 nm
d. 635-750 nm - CORRECT ANSWER-c. 350-400 nm
When the lenses are laid out and marked for cutting and edging, the lenses are
usually decentered so as to correspond to the patient's pupillary distance after
lenses are inserted. This is done for the following reason:
a. to avoid unwanted prism
b. for cosmetic effect
c. to use off-center lenses
d. to avoid thick edges on the nasal side - CORRECT ANSWER-a. to avoid
unwanted prism
Light falling on the front surface of a spectacle lens is:
a. partially reflected, partially absorbed and the remainder refracted
b. partially reflected and the remainder refracted
c. partially absorbed and the remainder refracted
d. totally refracted - CORRECT ANSWER-a. partially reflected, partially absorbed
and the remainder refracted
A concave mirror:
a. can focus parallel incident rays to form a real image
b. can focus parallel incident rays to form a virtual image
c. always produces inverted images of real objects
, d. produces virtual images smaller than the real object - CORRECT ANSWER-a.
can focus parallel incident rays to form a real image
White light is broken into its component colors when it is:
a. diffracted
b. refracted
c. reflected
d. diffracted or refracted - CORRECT ANSWER-d. diffracted or refracted
To the viewer; the image seen in a plane mirror appears to be:
a. inverted
b. one-half as large as the object
c. twice as large as the object
d. as far behind the mirror as the object is in front of it - CORRECT ANSWER-d.
as far behind the mirror as the object is in front of it
The velocity of light is the least in:
a. air
b. polycarbonate
c. water
d. flint glass - CORRECT ANSWER-d. flint glass
A lens dispersing white light into its component colors is an example of:
a. achromatic abberration
b. isochromatic abberation
c. chromatic abberation
d. newton's fringes - CORRECT ANSWER-c. chromatic abberation
The optical center of a lens is:
a. at the geometric center
b. on the 180 line
c. at the point where "A" and "B" measurements meet
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