In order
Hi index is worst
CR39
Trivex
Poly
Glass
In order
Hi index is worst
CR39
Trivex
Poly
Glass
What's troubling me is that this patient has worn the same combination in the same environment for 10 years without issue until now. And 2 different labs produced the same results. Confounding.
The only variance is the actual frame. The current frame is angular, and some of the corners may be a contributing factor. It doesn't address the nasal, unless the string end is not fully seated in the channel. This will create additional pressure on the lens.
Without seeing the previous frames, this is only a conjecture.
My vote is either heat damage or the lens being too tightly mounted.
Amazing replies! Thanks a ton. Yes it is very much possible he moves out suddenly into the heat from an air conditioned room. Avoiding that would be tough as well when he is at work, I guess.
I could get them remade under warranty. But the last time around, a representative from Essilor came to our outlet due to emails from customer. The customer tried hard to convince the representative. The representative blatantly denied that he is seeing lens distortion and any such distortion if seen by the customer is under "normal technical specifications!" He further advised the customer to get their Forte UV range with Transitions Signature VII, which is thrice as expensive in order to minimize such distortions. Customer didn't oblige.
So you are suggesting a full rim with Poly will be more resistant towards such crazing and cracking? Also I'll tell our edger to keep it as loose as possible.
If this can solve I'm ready to get him another pair done without keeping my profit.
Not sure about the mounting. In my experience, CR39 in a nylor has a fair amount of give, even if the lenses are slightly big. As for heat damage, I can't see that the lenses were damaged during adjustments as compared to zyl. I have seen enough damage done by lazy opticians with CR/HI in zyls to notice the pattern. As for nylor, 1.67 and Poly will typically show this type of damage when strung too tight.Originally Posted by Robert_S
Poly would be the second to worst choice if tightness of the mount was involved. If the lens doesn't craze, sooner or later, the lens will start to crack along the groove. Going into a full frame may not satisfy your patient, since he has been in a nylor all this time. You might consider going into a 3 piece mount with TVX or 1.6, instead.
My assumption is that you are in India? If your patient has had this combination for years without issue, I can't see that AC to humid heat will cause this, especially since he hasn't experienced this in the past. I still go back to the shape of the frame. Does this frame have a metal keeper, or a nylon insert? If it is not nylon, then the shape of the lens may not be exact and the metal keeper is causing additional stress. I would try to get a hold of a pattern and have the lab trace that, instead of the lens. You might want to restyle into something more forgiving, say a rounder frame with a nylon keeper? Take a look at his history and compare frame choices.
Back to humid heat. I do not practice what I preach, sadly. I keep several mirror coated Poly and TVX polarized with BSAR sun frames in my glove box. The temps here in summer can reach into the high 90F-100F. Imagine how hot my car gets? Still, my suns do not exhibit any of these issues, even with the AC running full blast. I have 3 drills, 2 metals and 2 Zyls in my glove box currently. Yes, I'm a sun junkie! My mirror coatings use the same SI02 layers as AR, with the same hydro layers applied. One would think that the lamination would fail, or the coatings would fail, but no. They are still in tact going into summer #2.
Just another item to contemplate.
Thank you so much, knowledgeable peeps, for the valuable replies.
I have a copy of his frame. It is metal on the top with nylon under the metal. The nylon continues as a ring all around the lens. The whole lenses are grooved all around. Not sure about his previous frames that never gave problem. I can call him again to check. He is keen on solving the problem and I am sure he will oblige if I told him to go full rimmed. He'll even go for poly that costs twice as much if I assure him, but I don't think he'll go for Trivex that has a list price of 14,000 INR onwards, which is 5 times of CR. Also very few manufacturers make them here.
He left a pair of recently crazed lenses last time. I examined closely and noticed the damage is more along the frame side and much more along the nose. The damage is much less to non-existent along the nylon cord.
I called up a few dealers, but no one has rimless nylon cord frame. Like this one: They haven't heard of such a frame, neither have I sold one like this ever.
How about a full rimmed metal frame with rounded corners + polycarbonate lenses and no grooving to fit? Will that solve this crazy crazing problem?
If heat isn't the culprit, lens flex very well could be. In that case, any plastic can fall victim to that given the right circumstances.
I'm guessing it's the heat primarily because he says the lenses were pristine when new, but goes progressively worse when he exposes them to sunlight when commuting to work.
I have had the unfortunate luxury of glazing several frames like this one in the past 5 years. Can't remember the MFR, but it was not fun. Just wondering why the frame designers thought that this was a good idea? A 3 piece in this style makes more sense and will be thinner and lighter. Oh well.Thank you so much, knowledgeable peeps, for the valuable replies.
I have a copy of his frame. It is metal on the top with nylon under the metal. The nylon continues as a ring all around the lens. The whole lenses are grooved all around. Not sure about his previous frames that never gave problem. I can call him again to check. He is keen on solving the problem and I am sure he will oblige if I told him to go full rimmed. He'll even go for poly that costs twice as much if I assure him, but I don't think he'll go for Trivex that has a list price of 14,000 INR onwards, which is 5 times of CR. Also very few manufacturers make them here.
He left a pair of recently crazed lenses last time. I examined closely and noticed the damage is more along the frame side and much more along the nose. The damage is much less to non-existent along the nylon cord.
I called up a few dealers, but no one has rimless nylon cord frame. Like this one: They haven't heard of such a frame, neither have I sold one like this ever.
How about a full rimmed metal frame with rounded corners + polycarbonate lenses and no grooving to fit? Will that solve this crazy crazing problem?
This is a case where there is no longer a correct answer, but trial and error. i am having issues with my hard coat and AR stack. An issue that has raised its ugly head in the past three weeks. No changes in coatings, no changes in workflow, no changes in edging protocols. Our AR vendor and coating vendor have been brought in to help troubleshoot. So far nothing. maddening.
Your situation seems similar in a strange sort of way. 10 years without an issue, and after 2 separate labs, a crazy issue. At least, your patient seems very understanding and willing to work with you....unlike my situation.
My sincere condolences, yuck...
The customer is prepared for a new pair of lenses but he says he'll do them from me only if I assure him this problem will never happen again. I'm trying to eliminate all sorts of probable odds - changing to full frames, changing to polycarbonate, no strings. It's a matter of prestige this time, and I'm starting to doubt the spectacle cleaner too.
We sell this one: http://contacare.com/spectacle-lens-care/speclean/
No one has ever complained, but then again, tbh, most people don't spend as much on lenses as this customer does. They get simple ones with/without AR; transitions is out of question - probably 1 order a month at the most. Maybe most of them ignore AR crazing distortions.
Is it possible that this spectacle cleaner is the culprit? It doesn't have any ingredient listed. Just a pale blue solution. I tasted it to make sure it doesn't contain anything corrosive; it tastes much like water, with a very faint soapy taste.
I could suggest him to use dishwasher/handsoap but most of them contain citric acid. Is Dove beauty soap bar safe for cleaning lenses?
If this client is demanding 100% assurance this wil never hapen again, your best/only recourse is to refund his money, and walk away. Honestly. There is literally NO way that ANY ecp can guarantee that with 100% certainty. There are just too many variables, and most of them lie in the client's control. I still lean heavily towards heat or rapid temperature change, possibly with the addition of lens flexure. I cannot rule out 100% that the nylon string being too tight could possibly cause this. I just don't see that likelihood. The string itself would probably break first. But perhaps...
I agree with Uilleann. This is most likely a problem of hard coat crack and it could happend again.
I would try Cr39 without hart coat if not want to refund his money.
I have one question. Hardcoat is treated with UV light to harden it. If a lens is exposed heavily to sun light which has UV, would that cause that the hardcoat film will become harder? Less flexible and easier to crack?
Promising it 'will never happen again' is out of your power. I would be sure to explain that. He sounds fairly reasonable but understandably irritated with the defect. All of these components are tested to be used together and tested to last, but unfortunately, flukes happen. If you wanted to guarantee no issues- offer him something with no frills. No trans, no AR- but who wants to wear that when they are used to the works? He needs to gauge that.
I recommend Dawn dishsoap for cleaning. I caution against pre-moistened wipes and honestly don't like the solution my location has- but that is purely because on the smell (think Twizzlers wrapper.)
Have I told you today how much I hate poly?
No. Once fully cured UV will not affect the hardcoat.
AR needs the hard coat to adhere.
As I recall Dawn is the most chemically infused dish soap out there and on anything but the best AR coats should not be routinely used.
It's why they advertise getting the grease out of pans best and is more expensive than other soaps.
Am I remembering correctly???
I figure if it is gentle enough for oiled up penguins, it's safe enough for lenses. I specifically use the Olay formula. Otherwise my hands break out in the wintertime.
At home I use the Free and Clear- it's supposed to have less added in.
Just look at that face!
Last edited by Quince; 07-10-2017 at 03:41 PM. Reason: added cutesy photo to envoke sympathy
Have I told you today how much I hate poly?
Dawn is the most recommended soap for cleaning the excess hydro from AR. The basic, non-concentrated one. It rinses well and doesn't leave any residue. It's also great for dissolving oils from the eyewire.
Thank you! I searched for Dawn on Amazon. The only one I got is this: http://www.amazon.in/Ultra-Dishwashi...&keywords=dawn
It's imported and costs almost 2000 INR! That's the price of a pair of Zeiss/Essilor lenses without UV.
Is Dove bathing soap relatively safe an alternative? I'm guessing he'll need some soap at some point even if I suggest him to use plain water all the time, in order to get rid of the sticky spots.
Is this thing safe to use? http://godrejezee.com/
It claims to be soda-free and pH neutral. But it doesn't mention other ingredients. Indians widely use this on sensitive and expensive clothes.
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