transitions not getting dark

I have a problem that I hope you can help.
One of my patients recently purchased Transitions Flat top 28 plastic lenses, and she came back complaining that the lenses do not turn dark. I tested the lenses myself and the lenses will only turn to about 30% darkness even after few hours of exposure to the sun. I informed the lab of the problem and re-ordered the lenses; however the new lenses have the same problem. The patient is angry and I am not sure what to do. She had Transitions before and she knows and expects that the lenses should get much darker.

Could anyone tell me why Transitions lenses would not turn dark?
Would it be advisable to change the lenses to Sunsensors?

What is temperature there?

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Originally Posted by chip anderson

What is temperature there?

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High 80s

Put lenses under a black light for 30 min. See if they work better after.
I have a question into Jim Schaffer to see if this works, used to help Photo grays and photo browns.
I suspect that some transitions lenses (which are created by "imbibing) the transions material either don't get soaked long enough, or the lens itself it reluctant to imbibe. Of course, transitions doesn't ever suggest this may be a problem.

Chip:cheers:

:angry:

Are the lenses A/R coated?

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Originally Posted by Judy Canty

Are the lenses A/R coated?

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They are not a/r coated.
They are not poly.
They are regular plastic.

Hello drpark111,

At temps in the high 80's on non overcast days, the Transitions 1.50 Gray will darken to at least 20 to 25% Transmission. (75 to 80% tint depending on time of day, brightness of the sun). Between 11 and 2 are the brightest time of day, and UV is at its peak.

Sometimes perception is the lens is not that dark. A quick way to demonstrate the change is to cover half of each lens with a post it note. Take them outside, activate them for a few minutes and peel off the post it. It is very dramatic to see how much the lens has changed.

BTW, you do not have to leave a lens outside for extended periods to make it dark. After two or 3 minutes (on a normal day) the lens will darken to whatever the conditions at that time allow.
Now, in mid winter when UV is low, extended time outside may darken the lens darker than in the intial few minutes but that is because the cold temps slow the chemical reaction. It may take 5 minutes or so to hit maximum darkness on cold, overcast winter days.

Also, AR will not affect performance. If AR did affect the performance, you normally see a problem with the AR, it will have purple or red reflect in the normal green reflect. This is from a layer not having the proper thickness or somehow was put in out of order. It has been a while since I saw one of these.

I hope this helps.
Feel free to call if you have any questions.
best regards,
Jim

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Originally Posted by Judy Canty

Are the lenses A/R coated?

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Why did you drop this question? Will AR affect the performance?

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Originally Posted by Jim Schafer

Also, AR will not affect performance. If AR did affect the performance, you normally see a problem with the AR, it will have purple or red reflect in the normal green reflect. This is from a layer not having the proper thickness or somehow was put in out of order. It has been a while since I saw one of these.

I hope this helps.
Feel free to call if you have any questions.
best regards,
Jim

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Jim answered that question already, more than once.

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Originally Posted by Judy Canty

Jim answered that question already, more than once.

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Yes I had read the explanation of Jim. When you dropped the question I thought that the AR will affect the performance.

I know this sounds crazy, but I swear, it works.
Put them in your freezer for 15 minutes. Take them out, put them in the sun for a few good minutes, let them get good and dark.
Something about chlling them first activates more of the chemical in the lens, thus producing deeper tint ever after.

EyeFitWell,
Cold temps slow down the chemical reaction of uv darkening a lens. By that I mean the molecule is held longer in the open (or colored) position. The millions of molecules in a photochromic lens open and close rapidly, heat and cold affect the speed of the reactions.

Whenever more molecules are in the open position, the darker the lens, heat up the lens and more molecules will be in the closed (or clear) position, the lens will not be as dark. This is part of what we call balance of properties.

All putting a lens in a fridge will do is cause one activation cycle to be darker than normal. It will not make the lens darker than normal in future activations and that is the urban myth that went along with placing eyewear in the fridge (or freezer)

Jim

Jim-
Really? B/C I was taught that the labs froze their transitions and then activated them. In fact, lately, customers have complained about their transitions not getting as dark, and when I told them to freeze them, they called back and said it worked.
Is there some other way to do a first activation? Or any other suggestions about how to make their transitions get darker?
Wow... I've been doing the freezer thing for years...

EyeFitWell,
Transitions and all other non glass/mineral photochromic lenses activate on their first exposure to UV light. There is no magic bullet. The performance on the first activation is as good as the UV index of the hour and day or the strength of the UV wavelength of a UV bulb if it is done in doors.

If the lens is cold or colder than a lens at ambient temps, it will get darker, for that one performance cycle, that's it. It wont be jmped to a new dimension of performance.

I visit many labs every year, I have yet to have a lab tell me they put Transitions in a freezer/refrigerator.

best regards,
Jim

Wouldn't you know that as I was leaving an account this afternoon, I overheard an optician instructing a patient via the phone to put them in the freezer for an hour and them put them in bright sunlight!

AAAAARRRRRRGGGGGHHHHHHH!!!

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Originally Posted by Judy Canty

Wouldn't you know that as I was leaving an account this afternoon, I overheard an optician instructing a patient via the phone to put them in the freezer for an hour and them put them in bright sunlight!

AAAAARRRRRRGGGGGHHHHHHH!!!

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Did this optician at least instruct the patient to take them off first!:hammer:

Yikes....I didn't stop to ask! I guess we'll just watch the local news and find out...:eek:

Sometimes, I wonder if it's not just having the patient do something, and they believe it works since they participated in the success.

Diane

Similar in principle, to the "cold water adjustment" to an already perfectly adjusted frame? :)

Does anyone have any suggestion on making Glass trans lenses darker? We have already heat treated them and it has not helped. They are the thin and dark ones already as well.

Hi Carrie,
Transitions Optical does not or ever produced glass photochromic lenses..Corning was the originator of glass photochromics!

I see you heat treated the glass product, this is for improving impact capabilities. I do not recall that this treatment kicked in the silver halide technology of glass (mineral) photochromic lenses.

Whenever I ordered glass samples from Corning, I conditioned them by exposing them to full sunlight, then reversed the reaction placing them in a dark area until they were clear. I did this several times. This conditioning did several things, mainly eliminated the yellow tinge of a spanking new blank and the lens performed closer to what a patient would experience in everyday tasks.

I hope this helps.

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Originally Posted by Carrie

Does anyone have any suggestion on making Glass trans lenses darker? We have already heat treated them and it has not helped. They are the thin and dark ones already as well.

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Carrie: Welcome to Optiboard!

Since the photochromic material is within the lens metrix, you could also opt to produce the lens with more thickness......the "thin" lens means less reactive material, so just 1mm (or whatever is tolerable) added lens thickness, will create a darker lens.

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Originally Posted by Jim Schafer

I see you heat treated the glass product, this is for improving impact capabilities. I do not recall that this treatment kicked in the silver halide technology of glass (mineral) photochromic lenses.

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Originally the glass Photochromic lenses were all heat treated and later chem-tempered as it provided better results.