# Optical Forums > Ophthalmic Optics >  Cutting Down A Lens For A New Frame

## rtperry

Hello everyone. I am sure someone can help me with this. A patient comes in and decides they want a new frame. They want too cut down their old lens too fit this new frame. Usually smaller then their old. How do you determine if the lens will cut down for this frame. Usually they have a bifocal or progressive lens. Is there a formula that I can use for this? And then how do you go about blocking it to cut it down.  :Confused:   This Optiboard is a great place!!! I always come here when i need a question answered. I don't feel so stupid. Like I do at work sometimes. Thanks too everyone.

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## Cindy Hamlin

RT,
My general rule of thumb was to take it down by hand, therefore; it couldn't be that much bigger.  I would never but down progressives or bifocals.  Mainly due to the increased risk of it going wrong and the cost.

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## rsandr

> How do you determine if the lens will cut down for this frame. Usually they have a bifocal or progressive lens.


If you find a frame with a smaller eyesize/shape and a *larger* bridge size then you should manage to get correct centration.
I tent to steer clear with progressives though. Once you've cut them if they have problems theres no recovery.
If they want a cut edge and fit with single vision lenses and its a close call i generally just give them a new pair and say nothing.

Rick

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## mrba

There is no reason a BF or progressive should come out wrong as long as you pick a new frame where you can do your old fashoned decentration for each lens and it cuts out.  You may have a seg ht change, and you will have to take that into account as well.


All patients should be told that the procedure is at their own risk, and should feel that they have nothing to lose beforehand.  If they do not want to risk it then it shouldn't be done.

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## Shutterbug

You can trace around the sample lens from the new frame, then plot the position for the new PD on the drawing.  Lay the old lens over the drawing with the OC at the PD marks, and determine if the seg height will cut at an acceptable height.  If all looks good, then go for it.  It will be fine.

shutterbug

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## Spexvet

Redraw the markings on the old lens. Dot your placement on the demo lenses in the new frame. Hold the center of the cross of the old lens over the dot on the demos. You should be able to tell if the old lens does not overlap the demo.

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## mkmlafrance

If the old lenses are a bifocal or a progressive I dot the lenses up, bifocal I just make sure there is no prescribed prism, then I take the measurements for the new frame block up the lenses, then take the geometric center of the old lenses put over the center of the block, that will let you know if it will cut out or not...single vision i just dot up on the lensometer and block up, get the geometric center of old lens and put over the center of the block....bam, if it has gaps it will not cut out, no gaps then it will cut out....We dont normally re-cut progressive lenses becuase the seg hts and decentration seem to screw up on the change over....

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## Raanan Bavli

As someone who has checked many many lenses before and after dispensing, I think the the following comment carries some weight: Most dispensers cut PALs in such a way that the prescribed position of reading power touches the lower edge of the cut lens. Often, the reading power is OUT of the frame !!!  Now, when you are going to cut an already-dispensed lens, you should first verify that the previous dispensed has not already cut you off this option.

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## Chris Ryser

> *.............Often, the reading power is OUT of the frame !!! Now, when you are going to cut an already-dispensed lens, you should first verify that the previous dispensed has not already cut you off this option.*


Finally somebody is making good sense.

Many opticians sell a smaller frame when the need to re-cut lenses arises. And as you said there might be barely any reading segment left on the previous older frame.  

Thanks god for all those small frames that people want where the progressive part takes all the bottom of the frame and people have 2mm of full addition left.

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## grace angel

Hi!  You fail to mention what kind of lenses you want to cut down.  If you are able to keep the OC in front of the pupil (so as not to induce unwanted prism) and adhere to ansi standards for edge thickness and so forth you might be able to accomodate the patient.  I just wouldn't try this with progressive, multifocals or apsheric lens designs as you'll be cutting away the optics that were originally decentered and calculated for a larger eyewire size.  You might get away with it in single vision lenses but be sure all the optics don't disappear into the edger.  (as with the example of lenses of ashperic design)  Personally, i'd give the guy a discount and strongly recommend new lenses!! :Cool:  Grace Angel

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## Chris Ryser

> *Personally, i'd give the guy a discount and strongly recommend new lenses!! Grace Angel*


Why sell new, new, new????

Is it not, that opticians are specialised artisans? Work with their fingers, should have learned the trade by doing a job with their own hands? Should be able to do a repair job. 

At least us the old guy's never shied away from at least trying. In today's economy not everybody has the cash to go for new. In my book it say's that you help out somebody and save him a fair amount of money, which he probably does not have, you gain another customer including his family and friends.:finger:

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## grace angel

Hi Chris!  I wondered if you'd cut down the guys lenses to save him money if they were of aspheric design???  I don't think you'd be doing the guy much visual justice in doing that.  I'd visualize that lens as though horse looking through blinders.  Peripheral vision would be less than adequate and your best prayers would put the OC placement in its proper place.  (remember OC ht is lowered 1mm for every 2 degrees of panto)  Thanks for your input.   Grace Angel

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## k12311997

I gota say you guys are brave.      How about the patient you tell the risks involved, even get them to sign a waiver, and when it doesn't cut out or otherwise adhere to ansi he's standing in your shop yelling at you in front of other patients.  I'd rather the patient be upset at me for saying no than potentially ruining his glasses. maybee I'm just too much of a wimp

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## Chris Ryser

> *Hi Chris! I wondered if you'd cut down the guys lenses to save him money if they were of aspheric design???*


Dear Grace Angel, I considered myself always as pretty good. I am able to measure, up and down, and also sideway's.

If after all the checking I would see it could not be done, I would say that it is not possible to do it. This is a precision job, remember optics is a precision profesession? If it would be possible I would do it,very simple. Good job done - happy customer. You have to know your limits.

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## shellrob

There's nothing wrong with selling the patient a new pair of glasses. It's our job and as much as some people on this board have a problem with that, it is that....our job. Yes, we are here to try to help the patient as much as we can and do what is the best for them, but it is our job and we do it also to make money. That's kind of why we have jobs. Ok ok, we love it too, but most of us probably wouldn't do it for free. So, if you can edge the lenses, great, it not...then by all means offer to make him/her a new pair of glasses. They will obviously need them and you make some money too. 



Oh, and my edger will calculate whether the old lenses will go into the new frame or not. Just fyi. Good luck to you.

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