Adding +0.25 D to the add power for progressives

[Daniel Cunningham]

Hi:

In the past, it was acceptable to add a quarter diopter to the add power for progressive lenses BUT now I'm hearing that it no longer is.

WHY?

Thanks.

Daniel

[Jubilee]

Some people did this in the past to compensate for losing part of the add power. In the days of longer corridor designs, if you wanted to fit someone at a 20 seg height, and the manufacturer said minimum fit was 22, a decision could be made to raise the add to make up for lost reading area, by making them find the full power a bit sooner.

Today's progressives offer a variety of corridor lengths to where this shouldn't be an issue. By bumping the add to compensate, the patient was losing a larger reading area. Great I can reach my reading power earlier, but I can only see 5 letters in width! (not a great solution)

[Joann Raytar]

See Darryl's post from another thread:
http://www.optiboard.com/forums/show...19&postcount=5

Some ODs over-plus or "bump" the add power with progressive lenses for one of two reasons:

1. Years ago, the old Varilux II lenses were introduced, which produced excess plus power because of the asphericity in the periphery of the lens. Consequently, some advocated increasing the add power in conjunction with extra minus in the distance power to compensate for this effect. Many "old-timers" might still take this approach. However, lenses are no longer designed like this, so it is not necessary today.

2. Many eyecare professionals also increased the add power with progressive lenses in an attempt to allow the patient to realize his/her full add power at a shorter distance from the fitting cross, particularly in small frames. In a situation where the minimum fitting height cannot be achieved, the patient may be better served by having the frame lowered slightly, selecting a slightly larger frame style, or of course by using a progressive lens style designed for smaller frames -- like AO Compact.

There are several good reasons not to bump the add power with progressive lenses:

1. At least one study has shown that more patients prefer the prescribed add power for progressive addition lenses to the over-plussed add power.

2. Increasing the add power effectively shifts the patient’s area of clear vision up from the near zone and into the progressive corridor, which is often the narrowest region of the lens.

3. Increasing the add power increases the level of unwanted blur in the periphery of the lenses and narrows the areas of clear vision through the lens.

4. Increasing the add power beyond what the patient requires needlessly restricts the patient’s depth of field -- the range of viewing distances through which the patient can clearly see his/her reading materials at near.


Best regards,
Darryl

[Bonilla-warford]

Hi:

In the past, it was acceptable to add a quarter diopter to the add power for progressive lenses BUT now I'm hearing that it no longer is.


Daniel

I don't want to start a war here, but isn't it the MD/OD who is supposed to specify the lens power? When I was an Optician I would see scripts written with "Add +0.25D if PAL." This isn't needed nowadays, but even when it was it was OD who would specify.

When I Rx a FT vs PAL vs NVFL I take working distances and patient needs in to account. I would not appreciate an Optician aribitrarily adding plus to my Rx. It seems a slippry slope from that to, "Oh, you want to see street signs more clearly, let me give you some extra minus...."

-Nate

[Joann Raytar]

But it doesn't take the frame fit and, in some cases, stubborn patients into consideration.

In the senario above, making sure the patient was looking through the prescribed power was what opticians were trying to achieve. What is on a boxtop or a lens envelope doesn't matter- it is what is read in the Vertometer and what the patient looks through. In the old days, if a frame was too small it would cut the add right off - by cutting a lens a step higher in add power it would insure the prescribed reading power made it into the frame. It caused the problems Darryl mentioned, but the patient looked through the prescribed add power.

[Jimdayok]

Another reason not to bump adds:

The newest PAL designs utilize the base curve and add power to determine the patient's insets. If you give a false add, you're changing the designed inset for that patient's RX.

[chip anderson]

If you need the extra quarter, the B measurment is too small or the Rx was under prescribed... I sometimes think doctors are hesitant to prescribe adequate adds because they got so much flack when they first told the patientess she needed bifocals. For the same reason I think they are hesitant to prescribe or suggest trifocals.

Chip:hammer:

[Barry Santini]

at the dispensing end knows for sure just how well suited the prescribed add is for *any* individual client. I will rountinely place the new Rx NV in a trial frame to see how it performs, both in acuity and depth of field. I will also discuss their reading/working habits, and I find these discussions are almost completely absent from the client's memory of being done during the exam.

From my local experience, refractions in most MD offices are "slam, bam, thank you mam!" It's my job to provide clean-up!.

Barry

[Fezz]

I will rountinely place the new Rx NV in a trial frame to see how it performs, both in acuity and depth of field.

Barry

All hail the trial frame! I use the darn thing more than I want to admit! It has saved me plenty of remakes and unsatisfied patients.

The trial frame has also been a tremendous help in increasing my multi pair sales. I like to figure out the patients "computer" or near rx and put it in the trial frame and explain the differences between the everyday progressive and the dedicated work, play, hobby pair. Works like a charm!

[Barry Santini]

All hail the trial frame! I use the darn thing more than I want to admit! It has saved me plenty of remakes and unsatisfied patients.

Yes, All hail!

Barry

[HarryChiling]

I like using the trial frame as well, but:

I don't want to start a war here, but isn't it the MD/OD who is supposed to specify the lens power? When I was an Optician I would see scripts written with "Add +0.25D if PAL." This isn't needed nowadays, but even when it was it was OD who would specify.

When I Rx a FT vs PAL vs NVFL I take working distances and patient needs in to account. I would not appreciate an Optician aribitrarily adding plus to my Rx. It seems a slippry slope from that to, "Oh, you want to see street signs more clearly, let me give you some extra minus...."

-Nate

In some states this is considered practiceing optometry. Just make sure to never switch out lenses and ask which one is better one or two. ;)

[Barry Santini]

I don't want to start a war here, but isn't it the MD/OD who is supposed to specify the lens power? When I was an Optician I would see scripts written with "Add +0.25D if PAL." This isn't needed nowadays, but even when it was it was OD who would specify.

When I Rx a FT vs PAL vs NVFL I take working distances and patient needs in to account. I would not appreciate an Optician aribitrarily adding plus to my Rx. It seems a slippry slope from that to, "Oh, you want to see street signs more clearly, let me give you some extra minus...."

-Nate

Not just in my state (NY), but in my book:

As long as I'm the one holdin' the bag (aka, responsible) for client satisfaction (not to mention expense in materials and disgnostic time) when *any* pair of glasses is not "right/satisfactory" (from the consumer viewpoint),you'll excuse me if, in advance, I try to

COVER MY ***!

Bottom line: If I see through experience that a refractionsist's Rxs do not need "second guessing"...I won't! Unfortunately, that is not the case where I am.

Barry

[Robert Martellaro]

I don't want to start a war here, but isn't it the MD/OD who is supposed to specify the lens power? When I was an Optician I would see scripts written with "Add +0.25D if PAL." This isn't needed nowadays, but even when it was it was OD who would specify. -Nate

I still see scripts with "Add +0.25D if PAL." I just ignore it.

And...

When I Rx a FT vs PAL vs NVFL I take working distances and patient needs in to account. I would not appreciate an Optician aribitrarily adding plus to my Rx.

This shouldn't be a problem if the optician is knowledgable and experienced. If the client can buy OTCs on their own why not let the optician red flag and correct an Rx with a bogus add power? I would rather get it right the first time, and it seems that you are thinking the same way- leaving no stones un-turned.

I don't fill a lot of OD scripts, but when I do they almost always get this right.

I will rountinely place the new Rx NV in a trial frame to see how it performs, both in acuity and depth of field.

That's how I do it. How many times have you seen the add go from +2.00 to +2.50 and the client (usually tall with long arms) holds the book at their knees. Sure, you can tell them they need to hold the book closer- but they are really uncomfortable doing so! Now we have a remake with a +2.00 or +2.25 add.

Regards,

[Bonilla-warford]

I like using the trial frame as well, but:

(my quote snipped)

In some states this is considered practiceing optometry. Just make sure to never switch out lenses and ask which one is better one or two. ;)

Harry, You and I are on the same page. The point I was making is that some Opticians *ARE* practicing Optometry without a license, and, at times, messing up what I spent time getting right the first time.

-Nate

[drk]

Just an aside, here...

Usually, prescribing adds is just common sense. It wouldn't hurt for a "poorer" vision care provider (ophthalmology techs) to let a good optician do the lens design and even specify the add power.

But in the real world, those Rx's could just as likely go out to Wally or the Borg, so someone on the prescribing side has to do it.

Nevertheless, a good relationship between professionals will clear up all problems.

[Aarlan]

If the client can buy OTCs on their own why not let the optician red flag and correct an Rx with a bogus add power? I would rather get it right the first time, and it seems that you are thinking the same way- leaving no stones un-turned.

I was just observing an OD in a medical setting (no dispensary affiliated) and they paid little heed to the refraction...It was just a quick glance w/ the phoropter, and her quote to the patient was, "if this doesn't work, just come back and I'll fix the prescription. Your optician will make the new lenses for free." !?!?!?!?!?!

I almost fell over! To whom would the cost be passed onto? (rhetorical question...the answer of course is the optician). What right does she have to set an expectation for the customer on behalf of the dispenser? I almost fell over.

AA

[Fezz]

Nevertheless, a good relationship between professionals will clear up all problems.

Now thats what I'm taliking about! Step on up Doc, this rounds on me!

:cheers: :cheers: :cheers:

[HarryChiling]

Harry, You and I are on the same page. The point I was making is that some Opticians *ARE* practicing Optometry without a license, and, at times, messing up what I spent time getting right the first time.

-Nate

Sorry if the sarcasim didn't come across, trial frames and add powers are not rocket science. We had a OD on here not so long ago who was changing adds in an online business where he was selling CVS lenses to consumers and opticals alike and people were loving it when he did it. When the axe falls on the opticians neck, then the otician should have the right to at least check the Rx for accuracy before fabricating it. I wonder if doctors take the lens form of their phoropter into consideration when writing their Rx? This can sometimes be anywhere from a 0.25D error to 0.50D. What about Vertex distance? What about any tilt present? The changes are called as worn, not modifications to your script, don't take it so personal it's the patients vision not yours.

[Bonilla-warford]

Harry,

Surely, we are all trying to do the best for the patients. I'm not trying to jump on Opticians for tweaking an add that some refractionist screws up. As drk said, a good relationship is necessary due to the overlap in professions.

What I would think would be improper, would be if I rx a particular add or lens design for a particular accommodative dysfunction and then an Optician somewhere arbitrarily alters the add, especially if it is so he or she can sell and particular frame. Unlike pure presbyopia and working distance, this area is complicated and cannot be resolved with a trial frame alone. Well meaning opticians can do harm without knowing it.

-Nate

[HarryChiling]

What I would think would be improper, would be if I rx a particular add or lens design for a particular accommodative dysfunction and then an Optician somewhere arbitrarily alters the add

Rx a lens design, now whos being improper? I think we have two different definitions of optician, and if harm can be done by fitting glasses talk to your congreesman about maybe licensing your state opticians.

[Bonilla-warford]

Rx a lens design, now whos being improper? I think we have two different definitions of optician, and if harm can be done by fitting glasses talk to your congreesman about maybe licensing your state opticians.

OK, so what is your definition of an Optician? Does your definition include treatment of accommodative dysfunction?

I don't think I need to talk to my "Congreesman." My licensed optician does just fine, thank you. But I do request they run changes to my script by me.

-Nate

[HarryChiling]

I didn't see that you were in FL. The alternative is sending a patient back to the doctor, who for some reason missed asking the patient about what the glasses would be used for in the first place. Accomadative dysfunction is not something an optician should be measureing, however it is not rocket science again.

to take a doctors add and convert it to a new add for a different working distance:

Add = (1/working distance) - acomadative reserve

assumeing a working distance of 30cm lets say an add of +2.50

+2.50 = 1/.3 - AR
+2.50 = +3.33 - AR
AR = +3.33 - +2.50
AR = +0.83

Now the reserve is totally up to the doctor to determine and this portion would be the area that an optician should not touch, however if at this poitn a differetn working distance is needed the optician can use the derived AR to determine a new add. Not rocket science and their is no change made by th optician related to accomadative dysfunction just a change in the focal length of the lens which falls within the scope of an average optician.

[Bonilla-warford]

I didn't see that you were in FL. The alternative is sending a patient back to the doctor, who for some reason missed asking the patient about what the glasses would be used for in the first place. Accomadative dysfunction is not something an optician should be measureing, however it is not rocket science again.

to take a doctors add and convert it to a new add for a different working distance:

Add = (1/working distance) - acomadative reserve

assumeing a working distance of 30cm lets say an add of +2.50

+2.50 = 1/.3 - AR
+2.50 = +3.33 - AR
AR = +3.33 - +2.50
AR = +0.83

Now the reserve is totally up to the doctor to determine and this portion would be the area that an optician should not touch, however if at this poitn a differetn working distance is needed the optician can use the derived AR to determine a new add. Not rocket science and their is no change made by th optician related to accomadative dysfunction just a change in the focal length of the lens which falls within the scope of an average optician.

This is true for the vast majority, Harry. And I wish all Opticians understund it as well as you do. But there are some patients where accommodative reserve isn't the problem, rather the relationship between accommodation and convergence. This requires a lot more work to get right in the first place and can be frustrating when it is screwed up. For example, an accommodative esotropic child may in fact be over plussed in lieu of prism. Arbitrarily backing down on the add may delay the gains he/she receives from vision therapy.

This all brings up an interesting (to me) point from my own life. I was ABOC before I went to OD school. There was a time in school when I questioned whether it was ethical for ODs to dispense at all. But then I realized that when I Rx lenses for particular needs, like Fresnel prism and yoked prism, it is much better to have the SRx filled by my Opticians than to some Optician who doesn't understand what I am trying to do with the lenses.
(Just curious Harry, do you stock Fresnel prism? How many Opticians do?)

Sadly, while ODs get lots of math and optics, optical benchwork is limited and edging is an elective. I do not agree with the current trend of ODs pushing for medical privileges, because I think it leaves behind what we do best - vision. But the world is changing rapidly and it is getting harder and harder for both independent opticians and Optometrists.


-Nate

[chip anderson]

Why stock Fresnel Pasters when there is never any ugency and they can be obtained from Fresnel in 24~48 hrs? There are too many of them for a small shop to stock and the use for them is too infrequent to make them a good shelf item.

Chip

[Bonilla-warford]

Why stock Fresnel Pasters when there is never any ugency and they can be obtained from Fresnel in 24~48 hrs? There are too many of them for a small shop to stock and the use for them is too infrequent to make them a good shelf item.

Chip

Depends how much you use it, doesn't it? I don't currently stock press on prism, but I will in the future. I've worked at places that did and loved it. Why? Better service. I'm going to use it, and it doesn't take up much space... why not.

-Nate