If the RX states to use a 2.50 addition for PAL and 2.25 for a bifocal, what would be the customary add to use this RX on a single vision reader? --Yes I could call the DR but I'm wondering if there is an understood default? I'm deducing it is 2.25 because like the bifocal addition a SV reader has only one focal point. Is this correct? Why would a DR prescribe different adds?
add of 2.25 is correct
As for the why, working in an office where the Dr. commonly does this. It has with corridor lengths in conventional progressives. It's a defense mechanism that some Drs developed from improperly fitting of progressive lenses either due to optician error or an intentional understatement of minimum fitting height from certain manufacturers. This is before my time but I've heard this enough times from the optician I learned from, when frame Bs started decreasing Varilux decreased the MFH of the Comfort (I can't remember from what to what) because the Ellipse was not ready yet. I do not know if any other manufactures did this but I know Essilor did. So, the add was getting cut off and so the solution that those Drs chose was the raise the add to compensate for the assumed add loss due to fitting problems. According to the Dr. I work for the risks from potentially over plussing the the patient at near were greatly outweighed by the benefits. As for why these Drs keep writing these RXs with two adds, I believe it's a combination of habit as well as patient history (this may also be habit, but in the case of the Dr. I work for even though he is not writing as many rxs with two different adds, for those patient that he always has, he always will)
Last edited by jpways; 09-06-2016 at 08:06 AM.
Kentucky windage?
There were two reasons to bump PAL adds in the past, a design flaw in the early PALs, and the lack of shorter corridor PALs prior to the late 1990's.Originally Posted by iokuok2
http://www.optiboard.com/forums/show...ll=1#post23619
Use the +2.25 for both SVNO and for PALs/multifocals.
Hope this helps,
Robert Martellaro
Science is a way of trying not to fool yourself. - Richard P. Feynman
Experience is the hardest teacher. She gives the test before the lesson.
In my area, all of the LC docs list two different adds. Take that as you will. A few of the MD offices will also. It's pretty common.
Interpret the add to the patients desired focal length and fabricate accordingly.
I think Doc's do this because they want to get them out of the chair! Let someone else have the long discussion necessary to offer the best option of the mind numbing choice of progressive designs out there today.
I'm surprised that LC is a big offender; usually they have an advanced certified optician available in some of the larger communities. Where are you located?
The key is to educate the prescribers; we can learn a lot a from them, and they can learn thing or two from us.
Yup, although the phoropter rod is right there in front of them. The ODs are pretty good at prescribing sensible, real word adds, where the MDs might not have properly trained and experienced refractionists.
Robert Martellaro
Science is a way of trying not to fool yourself. - Richard P. Feynman
Experience is the hardest teacher. She gives the test before the lesson.
LC having an ABOAC Optician in my area is almost a laughable concept. I guess the communities that do have such a thing should be happy, good to know Robert.
Yeah, Robert,I'm with Tallboy. I'm in an unlicensed state, and people working at LC don't even have an ABO. Around here they're taught to sell, not how to be an optician. I'd assume it would be better in a licensed state.
Thank you for all the info; I've got the drift. It sounds like if you make the segment higher than necessary you have less room for the portion that is used the most. Nothing is ever as precise or simple as I want it. Passing the ABO doesn't make me the jack of this trade either but at least it starts the conversation.
Your welcome, and welcome to Optiboard. Simply said, the add should be the correct value for the object/work distance, regardless of the multifocal design. Watch for long arms and those who prefer to hold their book/tablet on their lap. Moderate to advanced presbyopes require the most attention. Low vision clients may need higher adds with shorter work distances to take advantage of proximity (relative size) magnification.
I love to talk optics. Don't be a stranger.Passing the ABO doesn't make me the jack of this trade either but at least it starts the conversation.
Best regards,
Robert Martellaro
Last edited by Robert Martellaro; 09-19-2016 at 02:44 PM.
Science is a way of trying not to fool yourself. - Richard P. Feynman
Experience is the hardest teacher. She gives the test before the lesson.
From my perspective, I think the optician should be willing and able to design the lens for near use.
Really, I put patients in two baskets. (No, not those baskets!)
1. Presbyopes
2. Emerging presbyopes.
With (true) presbyopes (age 50 up, for the most part), they're going to need oftentimes multiple task-specific designs: occupational lenses, sun/sport lenses, etc. You can't design those from the chair; only the optician can do that*.
With emerging presbyopes (say, an add without the first digit a "2" ), you pretty much don't have to mess with it, anyway. But you could if you wanted.
*That's why I crack up/cry/explode when we get the call from the wholesale club..."What's the computer Rx"?
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