Yellowing of Lenses

[Irish]

I purchased a pair of glasses from Zenni and have been satisfied with
them except for the lens color change. I ordered a pair of glasses
that turn dark in the sun and that they did. Now, however, the
glasses are yellow and will not return to clear when I com einside. I
talked to Zenni and they said that is because of oxygenation. I
emailed them back and advised that that reply didn't help Were they
supposed to turn yellow and why don't glasses from other vendors turn
yellow? No response.

Has this occurred to anyone else? Is it a flaw?

[sj]

How long have you have the glasses?

Plastic lenses do turn yellow over time, I'm talking about 5 to 10
years. I suppose they'd discolor faster if you left them someplace
really hot or in direct sunlight, like on the dash of a closed up
car.

[Irish]

Mine turned yellow after 4 months.

[GG]

About a year ago I bought grey photocromic from Zenni (they offer no
other color). I have not been satisfied with them either. Even though
they go reasonably dark, they are very slow to go back to clear again.
Furthermore, they do not go back to completely clear. They are always
a little dark, even after you leave them in the case inside a drawer
for a couple of days. And this happens from the very beginning. So
much so, that I have ceased to use them indoors because they are never
completely clear and I don`t find them comfortable. I use them only
outside and in daylight. I have been using photocromic for some 15
years now, so I am familiar with that kind of lenses. Moreover I have
recently bought photocromic lenses from Optical4less (brown) and I am
completely satisfied. I am wearing them as I write this and have been
wearing them constantly since I received them a week ago. I'll post
about this glasses form Optical4less as soon as I can, but, for the
time being, I can tell you that they turn color much faster than
Zenni`s and, more important for me, they go completely clear at night
or indoors. I cannot tell you if Zenni`s have a flaw or not (maybe
they are just differently tuned?), and I know nothing about this
"oxigenation" they tell you, but I find Zenni`s photocromic are not
as good for me as Optical4less`s or to that matter, to other
photocromic lenses I have had in the past, because of this
characteristic of never going back to completely clear.
GG

[vern]

I'm new to this group and I am in the optical business. I am
intrigued by some of the issues I see that some people have. As far
as the issue of the photochromatics, I can say that some
photochromatics are better than others. There are only several that I
personally will use in our wholesale lab. I commend Zenni's for what
they offer at a price point, but the lenses that they use we chose to
turn down due to the issues discussed here. It has more to do with
the processing of the lenses more so than "oxygenation", which is a
explanation I have never heard of before in almost 18 years of making
glasses. When lenses no longer change color, it means that the
molecules in the lens are no longer expanding or contracting in the
material. These molecules are what absorb the light. If they are
turning yellow or staying clear or dark, it would mean that the
molecules are in a "stuck" status. If that is a good explanation.

Vern

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