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Thread: Weak Add Powers?

  1. #1
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    Weak Add Powers?

    I work for a large chain across Canada where we all share the same lab. Our particular location has been processing a large number of redos with the Essilor Progressive Natural. We have been finding weak add powers of at least .25 D (please note the "at least").
    Our latest redo for an OD Rx Plano -0.25 x 080 Add 2.00 was weak a full .50 D. The laser etching read a 2 add but the most we could get from it was a 1.50, the height was 21 mm. Now the information we have from Essilor suggests a minimum fitting height of 21 for the Natural yet we have a Progressive lens Identifier from the OLA that recommends a 24mm min height.
    You might think that the 21 mm is too low but a gentleman in the building where I work also wears the Natural with 21mm height and a 1.75 ADD which reads perfectly. I hope I am not losing my mind because if I am there are three more losing it at the same time. I know it is rare for the laser etchings to be wrong but I am beginning to think that there may be two Essilor Naturals out there with different corridor lengths producing min fitting heights of 21mm and 24mm. Anyways your input is greatly appreciated!

    PS This is my longest post to date, please forgive me...lol

    Thanks Brad

  2. #2
    Master OptiBoarder Jeff Trail's Avatar
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    Brad,


    BTW, posting becomes an addiction around this place.....


    I do a ton of Natural's and have not experienced any of that? hmmm... Did you call your Essilor rep and tell them what's happening?

    Well, off of that and onto the fitting problems.. One of the biggest problems when they say "fit this at ## mm" is this, they have NO way of knowing the frame size and or the mono PD so they are kind of just giving a generic recommendation.
    I know I have worked very hard with my accounts (I'm a wholesale lab owner BTW) and now have a great majority of them that do a lot of PAL's have put the "fitting" cards on all the tables in the dispensary...:) ..I finally have got them to understand it will make their job a lot easier and you can determine at the time of fitting what design is going to work best given the parameters of frame shape and PD.. they can just fit the frame, place a tiny dot or cross where the fitting cross will be ..lay the frame face down on the fitting chart and you will see EXACTLY where the power points will be (distant, reading) PLUS it made explaining to a patient "why" you can't work with that frame in the design or material you wanted.
    I know that it has decreased the non-adaption rate somewhat. Everyone of the frame companies have those type charts available and the vast majority of (stores, chains, OD's) dispensaries usually only deal with a "handful" of designs that they like so it's easy to have those charts placed on the table top..Shoot it even looks good!! Most of them have them under a plexi glass cover along the two edges of the desk and it does make it really understandable to a "laymen" when trying to explain how the lens works and what the area's mean and where they are located... (PLUS those cards are FREE) :D

    As for the laser marks on those PAL's being incorrect.. I have never had any that read differently from the mark to the actual add... was this reading BEFORE they were edged and mounted or after? (just wondering) .. I know that I have (before talking them into using the fitting cards) had a problem or two over the years where I have cut a lens design into a frame for an account where almost 3/4 of the add was edged away to get it to match the PD and hght. they wanted.. I call, and they usually just say "cut it the way it was written" than they have a non-adapt..(wonder why?) ... You can throw those "numbers" they give you from the lens companies right out the window and use the charts.. I have seen a hght. of 32 not work because it was in a pilot shaped frame with a very narrow PD!! Those numbers they give you are just a "generic" number..I have fit a Natural as low as 18 mm and with the right shaped frame and PD had the WHOLE reading area circle still there even edged and mounted.
    I have had a few (well probably more than a few) over the years that the "box" and the lens did not match up..even Essilor is not perfect.. but never had the problem you are encountering.. I would keep those lens and make sure you tag them and than give the rep a call.. no matter what anyone says I have never ran into a problem with working with the tech guys at Essilor and they usually go out of there way to help.

    Jeff "not affiliated with ANY lens company" Trail

    PS..unless they wanted to give me a few pallets of FREE lens blanks..:cheers: than I MIGHT toot their horn a little!!

  3. #3
    Bad address email on file
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    Jeff,

    Thanks for the reply.

    Unfortunately a visit to our optical by a rep of any sort is very rare at our optical. Our lab also does all the surfacing and edging. We simply send the frame off and take care of the final verification when it is returned, but I won't get into that. We are also one of those dispensaries with a handful, if that, of progressive designs.
    The two pairs I mentioned in my previous post were both marked using the Essilor fitting cards with the full reading circles visible. Because one was perfect and the other was so far off I have a lot of questions. My supervisor is meeting with our regional supervisor (who was previously an Essilor lens rep) to discuss his visit to our lab.
    - I would like to ask Essilor if there might be older generation lenses with different corridor lengths? (V2 lenses with Natural identification?)
    - I would like to know if our lab is verifying the add powers before and after surfacing?
    - And if necessary find out what our buyers are doing all day to get their pay-check.

    Well before I get too heated I think I'll close this post off.

    Thanks Again
    Brad

  4. #4
    OptiBoardaholic
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    Brad,
    Jeff makes a number of great points, as usual. Power checking in progressives must be done through the two checking circles (windows of simplicity built into the lenses for just that reason) which can be located using the layout charts. Moreover, to check the add you need to turn the lens around and compare the distance reading (front vertex power) and the near reading (also front vertex power), assuming that the progressive surface is on the front as they normally are. The difference will be the add. Like Jeff, I am yet to find one, of any brand, that differs from the engraving. Having said that, checking the add with back vertex reading is only likely to give you a significantly incorrect result if the lens is thick (plus). The lens you mentioned was plano in the distance.
    Regards
    David Wilson

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