Question-Prism Thinning

[EyeFitWell]

Question for ya, and this is just something I was thinking about, so please don't kill me if I'm way off...

Is it possible that some patient's experiences with PALS, in cases of nonadapt, that the prism thinning is part of what makes the lenses so uncomfortable?
Take for example a person who feels a lot of "swim." Would he or she feel that to the same degree w/o all that prism? I know it's cancelling prism, but that doesn't mean it's unnoticable, right? I mean, I wouldn't exactly want 10D BD prism in my SV lenses...

Does that make any sense?

[jofelk]

We have accounts that do not want prism thinning on any progressive Rx. They do not want to introduce a new factor that may cause a problem for the patient. We have also remade progressives to remove the prism thinning because it was a problem. However, this is only a very small percentage of Rx's.

[Angel of Grace]

I have dispensed many PAL's over the years and it is rare that a patients brain can differentiate the equithinning. Fortunately it is used primarily for the hyperope since corrective lenses for them are the thickest in the center and would tend to be much thicker as the lens transcended into the add power. Imagine the thickness without the thinnning process.

I do admit that i have a few patients that were visually sensitive to the thinning process and upon removing it remarkedly did well. I would say the % is so low that it would not make me ask the lab to not prism thin. If you use a good lab they should have no problem with remaking the lens at no charge without the equithinning.

:cheers: Happy New Year to All Optiboarders!!!:D :p

[AWTECH]

I have dispensed many PAL's over the years and it is rare that a patients brain can differentiate the equithinning. Fortunately it is used primarily for the hyperope since corrective lenses for them are the thickest in the center and would tend to be much thicker as the lens transcended into the add power. Imagine the thickness without the thinnning process.

I do admit that i have a few patients that were visually sensitive to the thinning process and upon removing it remarkedly did well. I would say the % is so low that it would not make me ask the lab to not prism thin. If you use a good lab they should have no problem with remaking the lens at no charge without the equithinning.

:cheers: Happy New Year to All Optiboarders!!!:D :p

The difference would not be the direct result of not using prism thinning but the luck of the draw in how the spherical cut on the back managed the power error by not using prism thinning. The reverse could apply with some powers where using prism thinning would reduce the power error on a particular Rx. Since between PAL blanks many Rxs are produced, some have less power error than others depending on how the Rx matches the hard front side blank.