The amount of reflection of each surface of CR-39 lenses is approximately - correct
answer. 4%
The absorption of light in lenses is classified by two variables. What are they?
A. base curve and thickness
B. index of refraction and thickness C.
thickness and lens transmission
D. tint and lens transmission - correct answer. D. tint and lens transmission
The denser the tint in a lens
A. the greater the transmission of light through the lensB.
the greater internal reflections in the lens
C. the less transmission of light through the lens
D. the fewer internal reflections in the lens - correct answer. C. the less transmission
of light through the lens
Standard transmissions in sunlenses should range between - correct answer. 15%
and 30%
If a person has exposure to sunlight at least 2 hours or more during the day, - correct
answer. their ability to adapt to night vision is compromised if they don't protect their
eyes from the sun exposure
A characteristic of dark tinted glass lens with an Rx of +4.00D sphere would be - correct
answer. dark in the center and lighter on the edge
Given a high plus or high minus Rx, which lens material would offer the best choice for
uniform density in a sunlens?
A. Pigmented glass
, B. CR-39
C. Trivex
D. B & C - correct answer. D. B & C
Although this may be the most popular color for sunlenses, it is not recommended for
patients with emerging cataracts - correct answer. Gray
_ added to any color increases contrast - correct answer. Yellow
_ is better than _ for improving contrast.
A. Violet/Gray
B. Green/Gray
C. Gray/Green
D. Gray/Violet - correct answer. B. Green/Gray
Glare is of more concern to which wearer?
A. Red haired patient
B. Computer user
C. Cataract patient
D. Presbyope - correct answer. C. Cataract patient
_ are generally inorganic materials (metals or minerals) that are vacuum deposited to
add color on glass lenses to give a uniform density of color on the lenses - correct
answer. Vacuum color coatings
What company introduced CR-39 lenses? - correct answer. PPG Industries
What is the index of refraction of polycarbonate? - correct answer. 1.586 or 1.59
The quality of today's polycarbonate lenses has been improved due to the demand of
what product? - correct answer. Compact discs
Birefringence is also referred to as _ and can result in distortion reducing the visual
performance to the wearer? - correct answer. Double refraction
What is the index of refraction of Trivex? - correct answer. 1.53
Features and benefits of Trivex include _
A. Superior optics B.
Impact resistanceC.
Ultra-light weight
D. All of the above - correct answer. D. All of the above
, Visible glare can be dangerous, because it can not only wash out colors, but in some
instances can cause - correct answer. photokeratitis
Polarized filters are made by stretching thin sheets of _ in one meridian - correct
answer. polyvinyl alcohol
Two methods for orienting the polarized filters into lenses include - correct answer.
laminating and molded
As light reaches a polarizing filter, - correct answer. light in only one plane will pass
through, having the other absorbed by the filter, thereby reducing glare
Polarized lenses were may not be recommended for which visual task? - correct
answer. Any visual task that may include using LCD instrumentation
Photochromic lenses were introduced by - correct answer. corning in 1964
The color change in photochromic lenses occurs as a result of _ that are added to the
molten glass - correct answer. silver halide crystals
The first successful plastic photochromic lenses were introduced by - correct answer.
transitions in 1991
Imbibed technology means - correct answer. that the photochromic technology is on
the surface of the lenses, which makes the color density not uniform throughout the lens
Corning's SunSensors utilizes - correct answer. in-mass technology, which means
that the photochromic crystals are in the matrix of the material which distributes
photochromic molecules throughout the lens, allowing a consistent and effective light
response for the life of the lens
Factors influencing darkening/lightening of photochromic lenses include
A. Intensity of light
B. Temperature C.
Age of lens
D. All of the above - correct answer. D. All of the above
UV filtering properties are inherent in which lens?
A. CR-39
B. PolycarbonateC.
Trivex
D. B & C - correct answer. D. B & C
How much UV is absorbed by a clear crown glass lens? - correct answer. 9%
answer. 4%
The absorption of light in lenses is classified by two variables. What are they?
A. base curve and thickness
B. index of refraction and thickness C.
thickness and lens transmission
D. tint and lens transmission - correct answer. D. tint and lens transmission
The denser the tint in a lens
A. the greater the transmission of light through the lensB.
the greater internal reflections in the lens
C. the less transmission of light through the lens
D. the fewer internal reflections in the lens - correct answer. C. the less transmission
of light through the lens
Standard transmissions in sunlenses should range between - correct answer. 15%
and 30%
If a person has exposure to sunlight at least 2 hours or more during the day, - correct
answer. their ability to adapt to night vision is compromised if they don't protect their
eyes from the sun exposure
A characteristic of dark tinted glass lens with an Rx of +4.00D sphere would be - correct
answer. dark in the center and lighter on the edge
Given a high plus or high minus Rx, which lens material would offer the best choice for
uniform density in a sunlens?
A. Pigmented glass
, B. CR-39
C. Trivex
D. B & C - correct answer. D. B & C
Although this may be the most popular color for sunlenses, it is not recommended for
patients with emerging cataracts - correct answer. Gray
_ added to any color increases contrast - correct answer. Yellow
_ is better than _ for improving contrast.
A. Violet/Gray
B. Green/Gray
C. Gray/Green
D. Gray/Violet - correct answer. B. Green/Gray
Glare is of more concern to which wearer?
A. Red haired patient
B. Computer user
C. Cataract patient
D. Presbyope - correct answer. C. Cataract patient
_ are generally inorganic materials (metals or minerals) that are vacuum deposited to
add color on glass lenses to give a uniform density of color on the lenses - correct
answer. Vacuum color coatings
What company introduced CR-39 lenses? - correct answer. PPG Industries
What is the index of refraction of polycarbonate? - correct answer. 1.586 or 1.59
The quality of today's polycarbonate lenses has been improved due to the demand of
what product? - correct answer. Compact discs
Birefringence is also referred to as _ and can result in distortion reducing the visual
performance to the wearer? - correct answer. Double refraction
What is the index of refraction of Trivex? - correct answer. 1.53
Features and benefits of Trivex include _
A. Superior optics B.
Impact resistanceC.
Ultra-light weight
D. All of the above - correct answer. D. All of the above
, Visible glare can be dangerous, because it can not only wash out colors, but in some
instances can cause - correct answer. photokeratitis
Polarized filters are made by stretching thin sheets of _ in one meridian - correct
answer. polyvinyl alcohol
Two methods for orienting the polarized filters into lenses include - correct answer.
laminating and molded
As light reaches a polarizing filter, - correct answer. light in only one plane will pass
through, having the other absorbed by the filter, thereby reducing glare
Polarized lenses were may not be recommended for which visual task? - correct
answer. Any visual task that may include using LCD instrumentation
Photochromic lenses were introduced by - correct answer. corning in 1964
The color change in photochromic lenses occurs as a result of _ that are added to the
molten glass - correct answer. silver halide crystals
The first successful plastic photochromic lenses were introduced by - correct answer.
transitions in 1991
Imbibed technology means - correct answer. that the photochromic technology is on
the surface of the lenses, which makes the color density not uniform throughout the lens
Corning's SunSensors utilizes - correct answer. in-mass technology, which means
that the photochromic crystals are in the matrix of the material which distributes
photochromic molecules throughout the lens, allowing a consistent and effective light
response for the life of the lens
Factors influencing darkening/lightening of photochromic lenses include
A. Intensity of light
B. Temperature C.
Age of lens
D. All of the above - correct answer. D. All of the above
UV filtering properties are inherent in which lens?
A. CR-39
B. PolycarbonateC.
Trivex
D. B & C - correct answer. D. B & C
How much UV is absorbed by a clear crown glass lens? - correct answer. 9%
