Receiving power error on manual lens mtter

[Farhan Hassan]

HI, SLAAM

HOW R U ALL

well now a days new technology PAL free form lenses back surfacing is very common i have tried many pair but but i am not satisfied with the power accuracy on my manual lens metter i just want to confirm that is that the PAL problem due Digital surfacing Or something Wrong with my lens metter. becouse conventional progressive are ok on my lens metter.

normaly error found in Aixs and, small power like -+0.25 / -+0.50 with any addition number,

kindly let know the truth...

farhan khan

[Robert_S]

Hello Farhan,

What lenses do you use?

Regards,

Robert

[Farhan Hassan]

hi robert

thank you for ur intrest first

well its about Cr 39 Free form lenses inside surfacing.

[Jason H]

Some digital lenses are compensated for face wrap and pantoscopic tilt so that they will read a bit different in a vertometer. Ask your lab if the lenses you use are compensated and if so ask them for a copy of the resulting rx. It may be a different problem than this but it would be a good place to start.

[Robert_S]

What lens design though?

[Farhan Hassan]

Thank you very much for your contribution in the postive way :) jason h

[Farhan Hassan]

Well robert its not any famous branded design like zeiss roden stock or essilor. Its easy lux design with 20to16mm fitting height from prp to nrd.

And unfortunatly i am facing the same power error in every design of easy lux by dehlawi optical industeries in jeddah.

Either its long design or the short design.

[Robert_S]

What I am trying to get at is if it is a conventional design manufactured with freeform (which doesn't improve the design much at all by the way, it just lets the lab make more money out of you)... and that seems to be the case. I may have misunderstood, but did you say the power issue was with the addition itself, or the whole lens? If it is the add, well that's a very common problem when you take an old design and freeform-surface it.

At low price points, you are better with traditionally surfaced lenses.

[Farhan Hassan]

Its total pal free form lens made on single vision

and the error is in the entire lenses not in only addition. I said power variation in distanse ....


I hope i got my point now and will give me better suggestion

thank u robert

[Robert_S]

I need to know exactly what lens design it is, or it is based on, for the same reason Jason asked; some lens designs will adjust the Rx. Most likely, if it is an economy lens, it is just being surfaced inaccurately.

[Farhan Hassan]

Ok so you mean if the blank is based on a good material so the power variation will not be received but if the production dept using poor material in blank so thies type of error will be continue. Is that the fact behind it...

They are using essilor sv blanks and the old sola stock of sv.

[GokhanSF]

Farhan kardas

If the lenses you get are free form there will be difference between the written Rx and the power read on the lens. This is due to wrap, tilt, and vertex calculations. If you don't provide these calculations LMS will use the default settings and process the lenses accordingly. Place the lenses on your manual lensometer and hold them the way they will be worn (vertex, wrap, tilt) and you should be able to read the Rx you ordered. Or you can ask the lab to sent you the compensated Rx and you should be able to read that on your lensometer.

Gokhan

[Robert_S]

Okay, thanks. Now, what is the name of the Varifocal you are selling and can you tell me what design it is based on or if it is a proprietary one. I suppose there could be some error in the sv blanks but I would expect very little from essilor lenses. Maybe from the Sola ones.

[Optician1960]

GokhanSF has it right on his second point: Get the Rx to inspect to from the lab with every pair, end of story. Do not try to replicate the fitting parameters in the vertometer to final inspect to the Rx you ordered vs the compensated Rx they manufactured.

Good luck

[GokhanSF]

GokhanSF has it right on his second point: Get the Rx to inspect to from the lab with every pair, end of story. Do not try to replicate the fitting parameters in the vertometer to final inspect to the Rx you ordered vs the compensated Rx they manufactured.

Good luck

And why exactly would you not try to read it properly?

By the way if you don't know how to read the Rx on a free form lens and can't relate to why the written Rx is different than the Rx you received, you don't know free form technology. So, why do you even sell something you don't know? I suggest you get some training on free form before you offer it your patients.

[Optician1960]

GokhanSF,
I think we can agree that FH is not taking the vertex, panto or wrap measurements himself so he does not know what is going into the LMS calculation. Now maybe the lab will tell him if he asks what these 3 measurements are, for each pair he orders, that goes into the compensation calculation. I'd bet a couple of dollars that even with that info, the likelihood that he is going to be able to place the frame in the vertometer at these precise measurements and then inspect the lenses is not very great (I feel the same way for most opticians here in the states). So why not take the easy and effective way out and just get the compensated Rx it is manufactured to?

[GokhanSF]

GokhanSF,
I think we can agree that FH is not taking the vertex, panto or wrap measurements himself so he does not know what is going into the LMS calculation. Now maybe the lab will tell him if he asks what these 3 measurements are, for each pair he orders, that goes into the compensation calculation. I'd bet a couple of dollars that even with that info, the likelihood that he is going to be able to place the frame in the vertometer at these precise measurements and then inspect the lenses is not very great (I feel the same way for most opticians here in the states). So why not take the easy and effective way out and just get the compensated Rx it is manufactured to?

Optician1960, I think for him the easy way is don't sell a product you don't know about :)

[Optician1960]

I will agree with you there 100% :)

[Robert_S]

I also agree.

[Farhan Hassan]

hi GOKHAN

THANK U VERY MUCH .
YEAH YOUARE MAY BE THE USING DEFFULT SETTING BECAUSE THEY DI NOT ASK ME TO PROVIDE THE P.A BVD. NRD. FACE FROM ANGLE. THEY JUST ASKED ABOUT THE FIITNG HEIGHT .

MAY BE THIS IS THE REASON FOR THAT ERROR.

THANK YOU AGAIN GOKHAN

[Farhan Hassan]

okay, thanks. Now, what is the name of the varifocal you are selling and can you tell me what design it is based on or if it is a proprietary one. I suppose there could be some error in the sv blanks but i would expect very little from essilor lenses. Maybe from the sola ones.

may this is the reason. But i found bit satisfaction about gokhan commetns.

But gain thank you

[Farhan Hassan]

gokhansf has it right on his second point: Get the rx to inspect to from the lab with every pair, end of story. Do not try to replicate the fitting parameters in the vertometer to final inspect to the rx you ordered vs the compensated rx they manufactured.

Good luck

yeah true dear

[Farhan Hassan]

and why exactly would you not try to read it properly?

By the way if you don't know how to read the rx on a free form lens and can't relate to why the written rx is different than the rx you received, you don't know free form technology. So, why do you even sell something you don't know? I suggest you get some training on free form before you offer it your patients.

gokhan i am agree with you but this is also resposibility of the production company to ask about the all perameters they need.

But i do agree with you said above.

[Farhan Hassan]

optician1960, i think for him the easy way is don't sell a product you don't know about :)

i have been using free form lenses for last few years ago and the asked for the details about pa bvd wraping etcc even nrd,,,. . Recently i switched the lab and they dint ask for these perameters even i tried to let them know. So thats not my fault,

i know what i am doing , but we are here to discusse our problem... Not ??

[shiyonghe1982]

GokhanSF has it right on his second point. I also agree! normal,we do Rx lens(not just free form) with prescrition sheet clients must be submitted.