Crazing on lenses.

**woyzek33** · 11-01-2012, 10:07 AM

I have had conflicting answers to my question on why we see now and again a patient with lenses that have horrible "crazing" marks on the lenses, like what you would see on very old pottery. Can anyone give me a definitive answer as to why they do this? Is it the scratch coat not adhereing to the material properly, is it a poorly applied coating breaking down, is it due to patient abuse, does it only occur on certain materials, is it to do with heat? Is it down to cheap lenses or are there many different factors involved.

Any help would be appreciated.

Bev

**braheem24** · 11-01-2012, 10:19 AM

SRC coating is your issue, get a DIP coating not SPIN (TD2 is a popular one) applied to both front and back of the lens before applying the A.R., your crazing issues will disappear.

**mcmanisdl@hotmail.** · 11-01-2012, 10:53 AM

I have had a few crazings happen when lenses with AR are in the heater too long with frame adjustments. Rare. My understanding is that crazing is from expansion and contraction differences between different layers of coatings.

**kat** · 11-01-2012, 12:16 PM

In Arizona we have a high crazing issue due to people keeping their glasses in the car, heat will craze a lens very quickly.

**Speed** · 11-01-2012, 12:19 PM

Are these crazall lenses?

**woyzek33** · 11-01-2012, 12:49 PM

Actually the lenses I came across today, were brought into me from another dispensary, he was getting fed up as this has happened to him 3 times in the last 6 months and they keep replacing them for him and they didn't have any AR on them. He insisted he doesn't do anything untoward with them, I wondered if he works with anything that includes any heat, he mentioned only cooking now and again, he is a retired gentleman. Unfortunately as I did not supply them, I can not really comment. I would just like to have been able to give him a firm answer. I'm guessing the hard coat they used would be really hard and I'm 95% sure they were poly lenses.

**Barry Santini** · 11-01-2012, 01:16 PM

Originally Posted by woyzek33

Actually the lenses I came across today, were brought into me from another dispensary, he was getting fed up as this has happened to him 3 times in the last 6 months and they keep replacing them for him and they didn't have any AR on them. He insisted he doesn't do anything untoward with them, I wondered if he works with anything that includes any heat, he mentioned only cooking now and again, he is a retired gentleman. Unfortunately as I did not supply them, I can not really comment. I would just like to have been able to give him a firm answer. I'm guessing the hard coat they used would be really hard and I'm 95% sure they were poly lenses.

Tharcle

B

**woyzek33** · 11-01-2012, 01:26 PM

Originally Posted by Barry Santini

Tharcle

B

elaborate

**Barry Santini** · 11-01-2012, 01:36 PM

I have a PP that explains all. Post or PM your email if your want a copy

B

**woyzek33** · 11-01-2012, 01:36 PM

Originally Posted by Barry Santini

I have a PP that explains all. Post or PM your email if your want a copy

B

Thank you, will do.

**Jubilee** · 11-01-2012, 01:53 PM

Hey Barry,

Will you send me a copy as well?

**shannon** · 11-01-2012, 02:17 PM

B- My interest is peaked as well....tharcle? LOL, couldn't even google it

**Barry Santini** · 11-01-2012, 02:25 PM

Please PM me your emails and I'll send you the PP

B

**MakeOptics** · 11-01-2012, 03:14 PM

Originally Posted by Barry Santini

Tharcle

B

I think what Barry is trying to refer to is THin Anti-Reflective Coated LEnses, it was a term made up by Essilor to describe the problem they created with their poly profile lenses. Since then many manufacturers have made really thin lenses that flex in the edger or in the frames with large A to B ratios. The powerpoint on "Tharcles" is pretty much what any edger manufacturer will recommend:

Reduce chuck pressure
Use proper cushioning pads
Use proper base chucks
etc.

Good luck with your crazing issues.