Photochromic Lenses - FINAL

Question 1

in glass lenses, the darkening agent is _

Answer 1

silver halide crystals

Question 2

do glass photochromic lenses wear out over time?

Answer 2

no, but they eventually do not return to their lightest state as a they did when new (fatigue dark)

Question 3

glass photochromic lenses are considered a _ lens

Answer 3

true sunglass

Question 4

there was a push to plastic photochromic lenses for what reason?

Answer 4

density/weight

Question 5

_ is the primary examples of photochromic technology using imbibition

Answer 5

transitions

Question 6

with imbibition, the photochromic molecules are permanently imbedded into the _ surface to a uniform depth

Answer 6

front

Question 7

with imbibition, the density of color is _

Answer 7

uniform across the surface regardless of rx

Question 8

gray variable polarized photochromic lens, maximum polarization 85%

Answer 8

transitions vantage

Question 9

method that mixes the photochromic dyes into the liquid lens material prior to casting

Answer 9

in-mass technology

Question 10

with in mass technology, lens darkness _

Answer 10

is not uniform - density is not uniform do darkness varies

Question 11

a drawback of in mass technology?

Answer 11

unable to deliver truly clear performance indoors due to the excessive photochromic dye

Question 12

with plastic in-mass technology, it lasts long how?

Answer 12

organic dyes near the surface wear out, UV begins to penetrate into the lens deeper and activate photochromic dye

Question 13

method where lens is dipped and cured with heat

Answer 13

dip coating

Question 14

coating front surface and UV cured

Answer 14

front-surface coating

Question 15

transbonding is used with what 3 materials?

Answer 15

trivex, polycarb, and high-index lenses

Question 16

a clear lens that has a 1mm layer bonded

Answer 16

multimatrix

Question 17

3 advantages of plastic photochromic lenses:

Answer 17

1) good UV protection
2) uniform density
3) light weight

Question 18

main disadvantage of plastic photochromic lenses:

Answer 18

life of lens depends hours of wear - problematic when one lens needs replacement

Question 19

when replacing a plastic photochromic lens, what is recommended?

Answer 19

replace both lenses because they will age differently

Question 20

are plastic photochromic lenses considered sunglasses?

Answer 20

no

Question 21

factors that influence performance:

1. light intensity -
2. temperature -
3. previous exposure -
4. lens thickness -

Answer 21

both
both
glass
glass

Question 22

the method that glass lenses are hardened (chemical or heat) affect _

Answer 22

transmission

Question 23

_ method of hardening the lens is preferred as it yields a darker lens

Answer 23

chemical tempering

Question 24

photochromic lens get darker on _ days

Answer 24

cold

Question 25

what is exposure memory with glass lenses?

Answer 25

they reach their full changing range and speed only after a breaking in period

Question 26

a well used glass photochromic lens will darken _ than an identical new lens

Answer 26

faster

Question 27

when replacing photochromic lenses, always _

Answer 27

replace in pairs