Thickness Problem with Physio 360 1.74

[sharpstick777]

Problem: New lenses are coming in from the lab very thick, thicker than his old 1.67's (his RX actually decreased).

RX:
+8.75 -3.25 x018 pd 32
+9.25 -3.25 x155 pd 31
add +1.75 OU

Frame: Flexon 422 Oval Shape 48/19 29.5mm B 48mm ED

Lens: Physio 360 1.74

I have received 2 pairs of 1.74 Physio 360's 1.74 with a min. edge thickness of 3.75 mm, CT of 9.5. His old 1.67's are at 1.5mm edge with a slightly higher RX and are way thinnner (CT of aprox 7mm). Patient is obviously unsatisfied that his 1.74's are way thicker than his old 1.67's.
The lab is telling me that this is the thinnest they can do these lenses, but can't tell me why.

Obviously switching lenses is an option, switching frames is not and his small oval is almost perfect for this RX. Anyone else have trouble with small frames in the Physio 360? And if we switched him to another Atoric lens, what would it be? 1.74 seemed like a best choice in material. Any answers would be appreciated.

Sharpstick

[Craig]

Problem: New lenses are coming in from the lab very thick, thicker than his old 1.67's (his RX actually decreased).

RX:
+8.75 -3.25 x018 pd 32
+9.25 -3.25 x155 pd 31
add +1.75 OU

Frame: Flexon 422 Oval Shape 48/19 29.5mm B 48mm ED

Lens: Physio 360 1.74

I have received 2 pairs of 1.74 Physio 360's 1.74 with a min. edge thickness of 3.75 mm, CT of 9.5. His old 1.67's are at 1.5mm edge with a slightly higher RX and are way thinnner (CT of aprox 7mm). Patient is obviously unsatisfied that his 1.74's are way thicker than his old 1.67's.
The lab is telling me that this is the thinnest they can do these lenses, but can't tell me why.

Obviously switching lenses is an option, switching frames is not and his small oval is almost perfect for this RX. Anyone else have trouble with small frames in the Physio 360? And if we switched him to another Atoric lens, what would it be? 1.74 seemed like a best choice in material. Any answers would be appreciated.

Sharpstick

You are in trouble with getting thin plus lenses from the 1.74 360 products at this point! They do have an 8 base lens that would be nice, but at that edge thickness they are way off on the calculations and are using bad data. The next best option is to call a lab who understands that the thinnest edge should be 1.5mm.
I would send it to Pech and have them calculate the thickness with various base curves that available in high index. Actually Harry should have the best choice for this type of RX in his head. I am not sure if a 9 base on 1.6 is better served than an 8 or 10 base.

Harry, where are you?

Craig

[sharpstick777]

I would send it to Pech and have them calculate the thickness with various base curves that available in high index. Actually Harry should have the best choice for this type of RX in his head. I am not sure if a 9 base on 1.6 is better served than an 8 or 10 base.

Harry, where are you?

Craig

I have not had good luck with Pech myself.

Sharpstick

[For-Life]

Why can't the lab do a knife edge? That is where your thickness is that.

Also, check the base curves.

[Jacqui]

Why can't the lab do a knife edge? That is where your thickness is that.

Also, check the base curves.

It's probably a software problem. It's a no-brainer when using the older equipment to get a knife edge everytime. This is one of the problems with the new ultra-modern, computer driven labs. The computers don't know how to compensate or watch the lens and the operaters (I can't call them opticians or lab techs) don't have a clue.

I would suggest trying a different lab, one that knows how to make lenses, not just punch numbers into a computer program.

[scriptfiller]

His old ones were probably surfaced with the frame enclosed. Are you ordering uncut, then edging them yourself?

I've noticed that with high plus, having the frame enclosed to the lab is the only way to get a decent thickness.

I don't find 1.74 index noticeabley thinner that 1.67. I had a pat come in needing a quick lense replacement, her old ones were 1.74, I ordered stock 1.67 and compared them the 1.67 was maybe .5mm thinner.

[C-10]

return the lenses and tell them you want a 6.5 center the edge thickness will come out to 1.0

[HarryChiling]

If you look at the VCA communications standards you will start to realize that the problem is int he software. A simple fomula exists for spheres, cylinders, aspheres, even atorics. But these new FF lenses use deformed conicoids and in the standards every point doesn't have to be specified you can use wildcards "?" for some of the points and the computer will calculate the point beased on the available data. The standard also dictates that the center points Z measure or coordinate is always zero so that will always be your start point, so to specify the edge would mean you would have to work from the edge in to the center and maybe even run through a few iterations to make sure you have an acceptabel thickness. Some FF lenses are still using rudimetary software to calculate the back surface. The technolgy no matter what you hear is still in it's infancy, it still has hicups. If it was google it woudl still be in BETA.

Craig, I'd have to go with high abbe lower index especially on this one. the lens being thick will have an effect on the transmission and the power will definately require a better abbe. Also a harder design is really really necessary you want something that is as wide in the channels as possible a backside design would be best. This is due to the ring scotoma effect of high plus lenses, this will destroy the channel of a front surface progressive. Maybe the unique in 1.67 aspheric front surface if possible or a hoya id in 1.70.

[optigrrl]

If you look at the VCA communications standards you will start to realize that the problem is int he software. A simple fomula exists for spheres, cylinders, aspheres, even atorics. But these new FF lenses use deformed conicoids and in the standards every point doesn't have to be specified you can use wildcards "?" for some of the points and the computer will calculate the point beased on the available data. The standard also dictates that the center points Z measure or coordinate is always zero so that will always be your start point, so to specify the edge would mean you would have to work from the edge in to the center and maybe even run through a few iterations to make sure you have an acceptabel thickness. Some FF lenses are still using rudimetary software to calculate the back surface. The technolgy no matter what you hear is still in it's infancy, it still has hicups. If it was google it woudl still be in BETA.

Craig, I'd have to go with high abbe lower index especially on this one. the lens being thick will have an effect on the transmission and the power will definately require a better abbe. Also a harder design is really really necessary you want something that is as wide in the channels as possible a backside design would be best. This is due to the ring scotoma effect of high plus lenses, this will destroy the channel of a front surface progressive. Maybe the unique in 1.67 aspheric front surface if possible or a hoya id in 1.70.

In addition to having better optics, the Hoya 1.70 is about 8% thinner than the 1.74 at that power.

[KStraker]

It's probably a software problem. It's a no-brainer when using the older equipment to get a knife edge everytime. This is one of the problems with the new ultra-modern, computer driven labs. The computers don't know how to compensate or watch the lens and the operaters (I can't call them opticians or lab techs) don't have a clue.

I would suggest trying a different lab, one that knows how to make lenses, not just punch numbers into a computer program.

So with this new fangled stuff you can't change the edge thickness? Makes me happy we still have a copy of RXP3. It's pretty simple, when you see the field for edge thickness, you input 1.5 instead of the 2.2 that our system defaults to. Tell the lab you don't care what kind of lens it is. The thinnest edge should be no thicker than the width of the eyewire.

[Jacqui]

Tell the lab you don't care what kind of lens it is. The thinnest edge should be no thicker than the width of the eyewire.

That will cause confusion :D :D :D

[HarryChiling]

Was the ET specified?

If it was then it doesn't meet the ANSI standard, if it doesn't then they're just cosmetically unappealing.

[RT]

If you look at the VCA communications standards you will start to realize that the problem is int he software.

I'm don't think that those are the dots that I would have connected here. I'm sure that Shanbaum, as the Chairman of The Vision Council's Device Communications Standard (DCS) Committee would extend an invitation to you to join us at one of the meetings so you could point out how the standard created this particular pair of thick lenses. Next DCS meeting is in Nashville next week.

More likely, what is happening is that the lab is running into limitations with their blocking system. Since FreeForm processes do not typically use wax blocking, the generator is unable to cut into the blocking material (or else it would ruin the lathe). On a high plus lens going into a smallish frame, therefore, the lens has to come out thicker to keep the lathe from hitting the block. When the lens is then edged out of the resulting surfaced lens, the edge thickness is thicker than desired. It all depends upon the diameter of the blocks available to the FreeForm process. I have no idea if smaller diameter blocks can be used in that particular lab's process.

[RT]

Was the ET specified?

If it was then it doesn't meet the ANSI standard, if it doesn't then they're just cosmetically unappealing.

Actually, a careful reading of ANSI Z80.1-2005 shows no mention of sepcifying edge thickness. If a CENTER thickness is specified, the resultant thickness must be within +- 0.3mm (however, FDA regulations always require that the lens be able to pass dropball testing).

One of the reasons that ANSI Z80.1 is not a "standard" but a "recommendation" is that ECP requests can over-constrain a job. If, for example, specifying edge thickness really were part of Z80.1, what would prevent someone for asking for a (-8.00) power with a 1.5 mm edge thickness? Of course the lens cannot possibly be made to that edge thickness.

One thing is for certain. The lab certainly has bungled this job, and even worse, bungled the communications to the ECP regarding the job. If there is some technical reason that the lab can't fabricate THAT lens thinner, they should indicate if they could fabricate a DIFFERENT lens thinner. The shoulder shrug is pretty unsatisfactory.

[HarryChiling]

I'm don't think that those are the dots that I would have connected here. I'm sure that Shanbaum, as the Chairman of The Vision Council's Device Communications Standard (DCS) Committee would extend an invitation to you to join us at one of the meetings so you could point out how the standard created this particular pair of thick lenses. Next DCS meeting is in Nashville next week.

More likely, what is happening is that the lab is running into limitations with their blocking system. Since FreeForm processes do not typically use wax blocking, the generator is unable to cut into the blocking material (or else it would ruin the lathe). On a high plus lens going into a smallish frame, therefore, the lens has to come out thicker to keep the lathe from hitting the block. When the lens is then edged out of the resulting surfaced lens, the edge thickness is thicker than desired. It all depends upon the diameter of the blocks available to the FreeForm process. I have no idea if smaller diameter blocks can be used in that particular lab's process.

shanbaum went over the mistake I made, teh standard still allows as much or as little data as possible to be feed into the process. I did not even consider blocks but that's an interesting note.

[JanMueller]

It's clear that a freeform product like the Physio is thicker than the former lenses that were probably a conventional design...
Always remember that a FF MUST be thicker than other designs.
It sounds dumb, but I have had great success with Impression Hyperop 1.67 from Rodenstock (I am german...) although it is a FF. In Germany we get the lenses uncut. With Rodenstock knowing the exact data of the frame we get the thinnest lenses I can think of.

[JanMueller]

It's clear that a freeform product like the Physio is thicker than the former lenses that were probably a conventional design...
Always remember that a FF MUST be thicker than other designs.
It sounds dumb, but I have had great success with Impression Hyperop 1.67 from Rodenstock (I am german...) although it is a FF. In Germany we get the lenses uncut. With Rodenstock knowing the exact data of the frame we get the thinnest lenses I can think of.

[Fezz]

Always remember that a FF MUST be thicker than other designs.

Really?

Why?

[JanMueller]

I have read so many articles from you, so it's an honour to talk to you...
(Excuse my school English, please).
If there are high plus powers combined with high additions, then the guys making the lens have to use higher base curve to get the same reading power like a conventional front surface design.
So it has to get thicker...

[Fezz]

I have read so many articles from you, so it's an honour to talk to you...
(Excuse my school English, please).
If there are high plus powers combined with high additions, then the guys making the lens have to use higher base curve to get the same reading power like a conventional front surface design.
So it has to get thicker...

The honor is all mine!

Welcome to Optiboard!!!!

[JanMueller]

Thank you Fezz. Like it here a lot.

[sharpstick777]

But our local rep and Hoya lab kind-a suck.

In addition to having better optics, the Hoya 1.70 is about 8% thinner than the 1.74 at that power.

[sharpstick777]

It's probably a software problem...

I would suggest trying a different lab, one that knows how to make lenses, not just punch numbers into a computer program.

All Essilor 1.74's 'Progressives right now come directly out of Dallas so it really doesn't matter what lab I choose, the problems is with Essilor.

It is a software issue I am told... they have dropped the thickness a little but not all the distance we need. I think it has to do with the system default min's set too high. They imput the correct data but the software overrides it. No success yet, and although I hate Hoya I may send the job to them.

[sharpstick777]

In Germany we get the lenses uncut. With Rodenstock knowing the exact data of the frame we get the thinnest lenses I can think of.

Rodenstock left the US market for 2 years. Although they are launching products again here I am not in any hurry to start selling the lenses (although I was a HUGE Multigressive fan). Not many labs are stocking Rodenstock blanks because they kind of burnt their bridges a bit...

Sharpstick

[JanMueller]

I am not that familiar with Essilor but if you choose a semi finished PAL like Comfort in 1.67 (is it available in 1.74???) where they don't have to calculate, shouldn't it be thinner ? Maybe there is a chance not to change to Hoya.