Retroscopic tilt - use short corridor?

[ak47]

I have a new patient that due to anatomy will have minor retroscopic tilt and wears +3.00 add progressives...shockingly enough, can not read well out of any of them and was currently wearing traditional Physio. Distance Rx is plano with both vertical and horizontal prism.

I am going to use FF and specify the tilt (I'm not sure which manufacturers will even allow panto less than zero)...I'm thinking a short, narrow corridor and wide reading because I can't imagine how the corridor would ever be useful..but I would sure appreciate your feedback.

[drk]

There is a new lens out for that. It's called the "Flattopio".

[rbaker]

There is a new lens out for that. It's called the "Flattopio".

Yes.

[bretk0923]

Shamir Duo?

You get no corridor then, but certainly would give you more freedom to bring the reading area closer to him.

[Kwill212]

Can you not switch the patient to a frame with more panto adjustment? I understand some people have low ears/high noses, some frame are virtually unadjustable, etc. But I would think solving the frame fit would be a better solution than trying to optimize a lens for a bad frame fit.

[ak47]

I wish changing the frame or the seg style would solve it. The patient is particular about the frame and it sounds like many of the frames in the past had the same issue. A flattop is a no-go for cosmetic reasons. I am intrigued by the Duo, but am trigger shy due to the prism (10D vertical, 8D horizontal). I am thinking something very short like Superior Balanced 8...thoughts?

[Kwill212]

If I were you I would decline the opportunity to disappoint this patient. Sounds like they want you to fix their problems but wont let you use the tools to do it. This has remake after remake written all over it.

[Robert Martellaro]

I have a new patient that due to anatomy will have minor retroscopic tilt and wears +3.00 add progressives...shockingly enough, can not read well out of any of them and was currently wearing traditional Physio. Distance Rx is plano with both vertical and horizontal prism.

I am going to use FF and specify the tilt (I'm not sure which manufacturers will even allow panto less than zero)...I'm thinking a short, narrow corridor and wide reading because I can't imagine how the corridor would ever be useful..but I would sure appreciate your feedback.

I wish changing the frame or the seg style would solve it. The patient is particular about the frame and it sounds like many of the frames in the past had the same issue. A flattop is a no-go for cosmetic reasons. I am intrigued by the Duo, but am trigger shy due to the prism (10D vertical, 8D horizontal). I am thinking something very short like Superior Balanced 8...thoughts?

Even if you could find a free-form manufacturer who will supply this much prism in a progressive, the chance of achieving adequate near vision is essentially zero.

For a progressive addition lens, try a Varilux old Comfort (semi-finished). Adjust the pupil heights and widths for the prescribed prism. Chances of success will be low. Supply auxiliary SVNO and/or primary segmented mutifocals for the best possible vision. Supply high Abbe materials for both, nothing lower than Trivex or maybe 1.60, minimizing blur due to chromatic aberration at all angles of gaze. Cr39 is better still if you think your client can handle the weight.

Hope this helps,

Robert Martellaro

[drk]

So let me get this right...

1. +3.00 add
2. Has to have retroscopic tilt
3. Fussy about cosmetics
4. 10 diopters of vertical prism
5. 8 diopters of horizontal prism

Sounds like a train wreck.

[Chris Ryser]

I have a new patient that due to anatomy will have minor retroscopic tilt and wears plano / +3.00 add progressives...shockingly enough, can not read well out of any of them and was currently wearing traditional Physio. Distance Rx is plano with both vertical and horizontal prism.

..........anybody selling such an Rx in progressives should be banned from optical heaven.

[lensmanmd]

I wish changing the frame or the seg style would solve it. The patient is particular about the frame and it sounds like many of the frames in the past had the same issue. A flattop is a no-go for cosmetic reasons. I am intrigued by the Duo, but am trigger shy due to the prism (10D vertical, 8D horizontal). I am thinking something very short like Superior Balanced 8...thoughts?

Not my lens of choice, but have you considered a seamless? I personally hate this lens, but if cosmetics is an issue, and with this RX, you might not have a choice for a single pair option. This patient would benefit most from a DVO and NVO, unless you would like to have one redo after another.

[finefocus]

Let me try to answer the question as asked. The effect of a viewing angle downward toward the reading area, in a lens angled retroscopicly, would be to foreshorten the corridor. To visualize this, take any lens, draw a vertical inkline on it, and hold it unangled an inch or two in front of your eye. Now tilt it retroscopicly. The line (and the corridor) apparently get shorter as the angle increases. Use a longer corridor, and fit it as high as the patient can possibly stand when (for example) driving.

[Tallboy]

I would use an Autograph III variable corridor with very careful POW measurements if the patient won't/can't switch to a more traditionally fitting frame or st28

[bretk0923]

I am intrigued by the Duo, but am trigger shy due to the prism (10D vertical, 8D horizontal).

If there is any kind of tropia, you will likely not have any success with Duo (or any progressive for that matter). If eyes do not converge correctly, the patient will land in a distortion zone. Also, like Robert says, I'm not sure that the parameters of Duo will comply. I'm on the 2 pairs bandwagon here. Honestly, I'd be surprised if even a flat-top works.

Good luck, sounds like you're going to need it.

[Robert Martellaro]

FWIW, I've never let a client walk out my door with retroscopic tilt. I just don't see how it can happen on purpose, unless there's a very unusual orbital bone or facial structure, neck injury, etc.

I do see very low values, Zero to threes degrees or so is not atypical with bigger frames. Check that you're using their primary gaze/visual axis, standing, as the reference position, and try to lose the retrotilt.

After all, he/she is wearing PALs with prism heretofore, all you have to do is make them perform better. Depending on the skills of the previous optician, that should be very doable.

Best regards,

Robert Martellaro

[Kwill212]

Let me try to answer the question as asked. The effect of a viewing angle downward toward the reading area, in a lens angled retroscopicly, would be to foreshorten the corridor. To visualize this, take any lens, draw a vertical inkline on it, and hold it unangled an inch or two in front of your eye. Now tilt it retroscopicly. The line (and the corridor) apparently get shorter as the angle increases. Use a longer corridor, and fit it as high as the patient can possibly stand when (for example) driving.

The same could be said for holding a lens an inch or two in front of your eye and tilting it pantoscopicly (clearly not a word), no? The line will still get shorter. But I would need a shorter corridor for more panto. I think a longer corridor for retro and shorter for panto is correct but due to the vertex difference between the two, not the apparent vertical shrinking of the lens.

[optical24/7]

I would firmly insist the patient select a frame that allows proper fit and positioning or I would decline to disappoint them. Educate them that PAL's are designed for panto not retro fitting. Even if he had some weird birth defect that left his ears on his neck, you can fit him in a Sihouette rimless ( I can tilt them puppies 45 degrees and adjust the nose pads to a 20mm vertex!)

You can recreate most full frame looks with edge tints, color grooves or sandblast around the lenses convex sides 1-2 mm around the edge, tint or color pen to achieve a full plastic frame look.

I don't like train wrecks. If possible, I'll do what I can to give a client the look they're after, but not if it results in a final product that just doesn't work optically.

[MakeOptics]

Heres a hint if the tilt has to be retro, you can tilt the back surface back to a more normal position using yolk prism. Look up the apical angle in your books and place the bevel towards the front so the back of the lens would hang out the back with the apical angle offsetting the retro.

[drk]

Highly creative but of dubious value, MO.

What good is a vertical back surface when the progressive curves on the front surface are tilting away? Put the progression on the back surface?

Maybe some incremental improvement, but man, that's getting to be a complicated solution!

[optical24/7]

That would be a neat trick MO, but the original posters mentioned 10D vertical prism (and 8 horizontal). I would think the LCA's from the prescribed prism alone would make that a no go adding yolk also on this particular Rx. The patient needs to fudge on his/her initial frame selection.

[drk]

Y--o--k--e...

Did you guys go to Waffle House this morning for green eggs and ham?

[optical24/7]

Y--o--k--e...

Did you guys go to Waffle House this morning for green eggs and ham?

Hey! You can have your prism yoked if you want. I like mine yolked ( and over easy..)!!








( It's early doc, give us dumb Opticians a break..)

[Robert Martellaro]

Probably due to loose cannon spell checkers, although my Safari browser isn't "fixing" yoked (Apple be smart), although it might have learned to spell it correctly after I corrected it numerous times.

[MakeOptics]

Highly creative but of dubious value, MO.

What good is a vertical back surface when the progressive curves on the front surface are tilting away? Put the progression on the back surface?

Maybe some incremental improvement, but man, that's getting to be a complicated solution!

With a +3.00 and 10/8 prism you can work out the numbers anyway you want the reality is the lens is never going to be clear in the reading using any multi focal so even the FT option isn't going to provide crisp clear vision. This client is going to walk away dissatisfied with any solution.

The best visually = two pair (let the flame wars begin)
The best cosmetically = yolked prism with some bevel placement to offset
The worst visually and cosmetically = Ignore it and order it in glass or plastic (sure the CA is going to be reduced but not enough to provide any significant improvement in clarity and the pair is going to look horrible)

Best solution, suggest there is an expert down the road named Drk that can do a bang up job. ; )

[ak47]

Can't we all just get along?