ABO Practice Test | Questions with 100% Verified Answers |
Latest Update 2026/2027
Question: 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
Question: 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
Question: 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
Question: 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
Question: 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
Question: 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
Question: 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
Answer: d. mixed astigmatism
,Question: 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
Question: 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
Question: 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
Question: 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
Question: 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
Question: 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
Answer: a. partially reflected, partially absorbed and the remainder refracted
Question: 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
,Question: 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
Question: 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
Question: The velocity of light is the least in:
a. air
b. polycarbonate
c. water
d. flint glass
Answer: d. flint glass
Question: 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
Question: 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
d. a lens location of zero deviation of the optical axis
Answer: d. a lens location of zero deviation of the optical axis
Question: 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
Question: 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
, Question: 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
Question: 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
Question: 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
Question: The color in white light that is refracted the most after passing through a refracting test medium is:
a. red
b. yellow
c. blue
d. violet
Answer: d. violet
Question: The reflection of light from a surface is most influenced by:
a. the index of refraction of the surface medium
b. the surface coating
c. the regularity of the surface
d. AR coating
Answer: c. the regularity of the surface
Question: Light rays originating at a distant point source are described as being:
a. divergent
b. convergent
c. parallel
d. refracted
Answer: c. parallel
Question: The incident ray, the reflected ray and the normal all lie:
a. in two planes, one perpendicular to the other
b. in the same plane
c. in two planes, each opposite the other
d. together, based on the angle of incidence
Answer: b. in the same plane
Latest Update 2026/2027
Question: 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
Question: 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
Question: 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
Question: 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
Question: 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
Question: 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
Question: 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
Answer: d. mixed astigmatism
,Question: 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
Question: 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
Question: 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
Question: 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
Question: 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
Question: 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
Answer: a. partially reflected, partially absorbed and the remainder refracted
Question: 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
,Question: 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
Question: 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
Question: The velocity of light is the least in:
a. air
b. polycarbonate
c. water
d. flint glass
Answer: d. flint glass
Question: 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
Question: 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
d. a lens location of zero deviation of the optical axis
Answer: d. a lens location of zero deviation of the optical axis
Question: 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
Question: 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
, Question: 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
Question: 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
Question: 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
Question: The color in white light that is refracted the most after passing through a refracting test medium is:
a. red
b. yellow
c. blue
d. violet
Answer: d. violet
Question: The reflection of light from a surface is most influenced by:
a. the index of refraction of the surface medium
b. the surface coating
c. the regularity of the surface
d. AR coating
Answer: c. the regularity of the surface
Question: Light rays originating at a distant point source are described as being:
a. divergent
b. convergent
c. parallel
d. refracted
Answer: c. parallel
Question: The incident ray, the reflected ray and the normal all lie:
a. in two planes, one perpendicular to the other
b. in the same plane
c. in two planes, each opposite the other
d. together, based on the angle of incidence
Answer: b. in the same plane
