When 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
d. front curve, back curve, thicknes...
ABO Practice Test
When 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 - 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 - 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 - 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 - 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 - 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 - Answer c. least plus power
The refractive error indicated by the Rx +1.75 -2.75 x 090 is: ABO Practice Test
a. compound hyperopic astigmatism
b. compound myopic astigmatism
c. simple myopic astigmatism
d. mixed astigmatism - 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 - 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 - 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 - 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 - 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 - Answer a. to avoid unwanted prism
Light falling on the front surface of a spectacle lens is: ABO Practice Test
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 - 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 - 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 - 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 - 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 - 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 - Answer c. chromatic abberation
The optical center of a lens is:
a. at the geometric center ABO Practice Test
b. on the 180 line
c. at the point where "A" and "B" measurements meet
d. a lens location of zero deviation of the optical axis - Answer d. a lens location of zero deviation of the optical axis
Light rays passing through a prism are deviated:
a. toward the apex
b. through an angle equal to the apex angle
c. toward the base
d. through the base - Answer c. toward the base
Light travels outward in all directions from its source. The best explanation of this is that light takes the form of:
a. radiated energy
b. luminous waves
c. wave fronts
d. straight lines - Answer c. wave fronts
The distance between the crest of one wave and the crest of the next one is called:
a. wave front
b. wave band
c. wavelength
d. amplitude - Answer c. wavelength
The interpretation of the range of wavelengths of visible light varies but is generally accepted as lying between:
a. 100 and 1000 nm
b. 300 and 400 nm
c. 400 and 700 nm
d. 500 and 800 nm - Answer c. 400 and 700 nm
The breaking up of white light into its component colors by a lens or prism is called:
a. diffraction
b. diffusion
c. dispersion
d. refraction - Answer c. dispersion
The color in white light that is refracted the most after passing through a refracting test medium is:
a. red
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