Shaw Lenses best for this patient???

[Uncle Fester]

Sixty Four year old female in FT28.

R -1.25 -2.00 x 173 4^ out
L +.25 sph 4^ out
Add R +1.75
L +2.00

Over 3^ vertical explains her double image at near and power difference is also inducing mild aniseikonia.

I know slab off fixes the vertical but is Shaw the only answer to the aniseikonia?

She is willing to give up cosmetics for function.

I believe Shaw requires I use them or can I have them made by other labs.

Will freeform generated lenses work?

I thought she may be better off with a more experienced optician but she's willing and wants to work with me and I do not see on Shaw's web site any area practice doing them.

Comments and suggestions appreciated.

For those unfamiliar with aniseikonia:

https://www.opticaldiagnostics.com/i...iseikonia.html

[drk]

Let's think:

If there was no lateral prism, for sheer anisekonia control, you could at least MINIMIZE the problem with equal base curves and center thicknesses. (Versus a true iseikonic lens, but I've "heard" that with minus lens powers like that, it's probably overkill.)

So you have this made on a, say, 6 base or a 4 base with 2mm CT.


BUT YOU HAVE lateral prism OU, but it's relatively equal. You may do slightly better to do less in the left (like a 5/3 split instead of 4/4) but that could be calculated, I'd guess, even at "Darryl's House" (Opticampus).


But you'd still have the downgaze prism imbalance, but like Raid, slab off would stop that roach dead in it's tracks, as you said.


In truth, while I'd have to think really hard to figure out the exact magnification differences between lenses, I'd bet is would come to less than a critical amount (which I can't remember, either...something like 3%, I'm guessing). I'd say you were OK to just ignore the whole aniseikonia thing other than having the smarties at the lab calculate for equal base and CT, and just worry about aniso prism in downgaze.

[Uncle Fester]

Thanks!

I'll hold out for today to see if any other thoughts get posted.

For those willing to fall down the rabbit hole:

https://www.optiboard.com/forums/showthread.php/70092-SHAW-Lens?highlight=Shaw+lensesAdd thread

[Jason H]

I'm getting a little over 3% magnification difference. What makes you suspicious of it? Slab off has it's place but I avoid it when I can. Not sure if Shaw does flat tops. Lots of questions.

[Uncle Fester]

I'm getting a little over 3% magnification difference. What makes you suspicious of it? Slab off has it's place but I avoid it when I can. Not sure if Shaw does flat tops. Lots of questions.

My first thought was this was not a big enough difference to be noticeable. She describes an overlapping gray image of the print she looks at.

[drk]

Gray? Hmm. Sounds like astigmatism or sumpin' (and there's lots of that stuff). See if it's there monocularly. "Negative for monocular diplopia OD, OS"

But you never know: a binocular-caused diplopia could seem "gray" I guess.

I wonder if you would get the chance to trial frame the victim's add power and have her use downgaze as though in a seg and measure the vertical imbalance with a Maddox rod. If she measured 2 or 3^, I'd trial that, and see if you were a Ghostbuster. (That would be a "positive for vertical diplopia on downgaze" finding.)

But I guess you could even trial frame the add power and have her look in straight-ahead gaze to make sure Casper disappears...a "negative for vertical diplopia" trial result. But if she still has a binocular ghost in straight-ahead gaze, that would possibly indicate aniseikonia.

But in reality, aniseikonia gives not frank diplopia, but strange "crossed diplopia" at the top of an image, and "uncrossed diplopia" at the bottom, giving things a "slanted" effect. It's killer rare.

[drk]

Yeah, and the ghost should be levitating rather vertically and less horizontally. Diagonal is OK, too. If it's pure horizontal, then it's not from a vertical prism imbalance, right?

[Jason H]

It would be interesting to know VA. If one eye can't see 20/20 there's your ghost.

[optical24/7]

Random thoughts;

How long has she had this power imbalance? If for very long, she most likely has developed a monocular reading habit. ( the longer the habit, the tougher to break). Does she have similar VA corrected? ( if not, has she displayed mono distance habits?)

As far as her Anseikonia, in CR39, 4.00 BC’s 13.5 vertex and 2.2 CT’s she’s experiencing a -.2/-4.5% @ 173 image size difference. You coulddesign Iseikonic lenses for her ( and with slab off). Changing the BC’s, CT’s and vertex distances (and materials, to a degree) are how they are made.

Changing these in the above to; R eye, 1.60, 8.00 BC, 15.5 Vertex with a 4mm CT
L eye, 1.60, 2.00 BC, 13.5 Vertex with a 1.8mm CT
will change the minification % down to +.5/-3.5 @ 173. You can play more with the % of difference by manipulating the BC, Vertex and CT even more, but then you may have a new can of worms to deal with on her off axis viewing since you are changing the base curves from “best design”. A solution to that would be for them to be made on a FF generator that is capable of atoric designs. No matter what direction you go, use a high abbe material to reduce the LCA’s that her prism induces.

Truly a challenging case there Fester! Keep use posted on process and outcome.

[jarralad2]

contact lenses make it easy to modfy magnification using telescopic principles.
have you considered it being due to different timing between eyes - often a problem in anisokonia

[Barry Santini]

contact lenses make it easy to modfy magnification using telescopic principles.
have you considered it being due to different timing between eyes - often a problem in anisokonia

tell use more

[jarralad2]

tell use more

For telescope you can calculate the power of spectacle lens and contact lens to create a telescope with magnification dependent on back vertex distance and lens power. Using different powers magnification can be varied with the air gap creating a thickness of lens. Its a long time since i did any eikonometry but when I did it, it worked well.

But, there is another technique.

Now we are into controversial areas.

When two eyes process information at different speeds there is often a significant refractive difference. This can cause a range of problems which are often difficult and in some cases impossible to address using conventional optometric methods. The problem is not refractive although it manifests itself as refractive. The first thing to do is change the processing differential. This is well accepted as being possible using the Pulfrich phenomenon. Early methods used a ND filter to change the speed on one eye relative to the other, but much better is to use univariance, although few practices have the instrumentation needed to acieve this. So, what can you do? The simplest method is to use lighting such as the Philips Hue light and compare processing speed of visual input with other sensory timing, such as lip synch. Each eye has to be evaluated independently. The illumination is then measured using a photo-spectrometer both in terms of colour space and luminosity. This then has to be convolved to take into account ambient lighting conditions (seriously complex calculations, particularly when multiple light sources are involved). From there you can calculate the filters that can achieve an equalisation of timing between the eyes. Fusion can become possible. Then you have to consider the refraction with the relevant light source, it can change significantly. But when you bring them it is possible to achieve good binocular vision, which clearly cannot be the case when they are disparate in time and space. This method has significant benefits in a variety of binocular vision problems such as alternating strabismus, convergence or accommodation difficulties etc. The science of visual timing is robust, using it in anisokonia is not - but it works!

[Uncle Fester]

After further discussion with her the "ghost image" was poorly described. We know slab off will correct the vertical prism but the off axis gaze is what really needs fix'n.

She's moved here recently from the Mid-west and always had a minimal mild plus spherical correction for her right eye even though cylinder was always present due to a corneal issue* that was recently addressed with Map Dot Dystrophy surgery (new to me!). The MD's office corrected with a -2.50 cyl power but that proved completely intolerable so our OD's refraction cut it back to the present 2.00.

She has always had issues with vision away from the optical centers but this high cyl is now all new to her and frustrating with any off axis gaze which her horizontal prism is exacerbating with vertical(?) (just read about this on another thread...gotta love my Optiboard!).

The new FT28 trivex bifocals are so distracting that she only wears them for distance when she infrequently drives as her gaze does not involve bumping into the seg lines.

She would like to have one pair do it all but will gladly use multiple pairs if that is the only practical solution.

Notes from MD: Pseudophakia OU , thyroid eye disease and *corneal epithealial and basement membrane dystrophy.

I need my doc to give me best corrected acuity tomorrow as I think it is limited.

Until then thanks for your input!

Now to buy more GAMESTOP stock!!!

[drk]

She sounds like an utter P.I.A.

Sorry, not sorry.

[Lelarep]

After further discussion with her the "ghost image" was poorly described. We know slab off will correct the vertical prism but the off axis gaze is what really needs fix'n.

She's moved here recently from the Mid-west and always had a minimal mild plus spherical correction for her right eye even though cylinder was always present due to a corneal issue* that was recently addressed with Map Dot Dystrophy surgery (new to me!). The MD's office corrected with a -2.50 cyl power but that proved completely intolerable so our OD's refraction cut it back to the present 2.00.

She has always had issues with vision away from the optical centers but this high cyl is now all new to her and frustrating with any off axis gaze which her horizontal prism is exacerbating with vertical(?) (just read about this on another thread...gotta love my Optiboard!).

The new FT28 trivex bifocals are so distracting that she only wears them for distance when she infrequently drives as her gaze does not involve bumping into the seg lines.

She would like to have one pair do it all but will gladly use multiple pairs if that is the only practical solution.

Notes from MD: Pseudophakia OU , thyroid eye disease and *corneal epithealial and basement membrane dystrophy.

I need my doc to give me best corrected acuity tomorrow as I think it is limited.

Until then thanks for your input!

Now to buy more GAMESTOP stock!!!

I can almost guarantee its limited. It really would have been nice if the doctor had specified the severity of the Graves’ ophthalmopathy (colloquially known as "Thyroid Eye Disease") it can range all the way from a gritty sensation of the cornea, to proptosis, corneal ulceration, ophthalmoparesis, and beyond. If she has limited movement of the eye, or uneven restriction of movement of the eyes, that could easily create these "ghosts". Having epithelial basement membrane dystrophy, the MDD surgery was likely of limited success as it isn't intended to be curative. The EBMD itself could also be the source of these ghosts, since it is known for creating issues with blurred vision in some gaze aspects.

Overall, I honestly don't envy trying to figure this out, you put those 4 different issues together, and I can't honestly imagine trying to come up with a solution that will produce acceptable results in all domains. I'm betting they overestimated how much the MDD surgery helped and the EBMD is causing trouble, which is why they avoided cylinder before. If the cylinder is cut back, I think it would likely help. I'd probably trial her with cyl cut back 1/4 diopter at a time until she either finds it acceptable, or it goes away. BCA will be compromised, but, I don't think that can likely be avoided. That's the best I can come up with.

[Uncle Fester]

Actually she has been a pleasure to deal with and very grateful to me for my searching for solutions. She has been dismissed by the optical community previously.

Also, I did speak to my Doc and she is corrected to 20/20 in the right eye. We're thinking of making a trial pair in cr39 using a spherical equivalent of -2.00 and see how she responds. Paying for this attempt is not a problem for her.

[It really would have been nice if the doctor had specified the severity of the Graves’ ophthalmopathy (colloquially known as "Thyroid Eye Disease") it can range all the way from a gritty sensation of the cornea, to proptosis, corneal ulceration, ophthalmoparesis, and beyond.]

It may be in the MD's letter. I'll have my doc review it tomorrow.

[optical24/7]

Bangerter filter the OS?

[Uncle Fester]

Bangerter filter the OS?

What level and why please.

Item No. ~ Snellen Acuity Level
6100 (1.0) ~20/20
6080 (0.8) ~20/25
6060 (0.6) ~20/30
6040 (0.4) ~20/50
6030 (0.3) ~20/70
6020 (0.2) ~20/100
6010 (0.1) ~20/200
60<1 (<0.1) ~20/300
60LP (LP) Light Perception
6000 (00) Total Occlusion (beige)


https://www.fresnel-prism.com/produc...clusion-foils/

[drk]

I would wager that the "ghosting" would be epithelial basement membrane dystrophy because it whacks out your cornea. You can see it, easily, with retro-illumination of the cornea, or fluorescein tear break up, or even keratometry mires. And it would be a low-contrast image.

I've found that the superficial keratectomies are very useful for EMBD patients.
HOWEVER, Fes is saying that she's complaining of off-axis ghosting, not central ghosting, and I guess the VA is 20/20. So I think that may just be a rabbit trail.


If she's worried about "ghosting" off axis, that's like chromatic aberration, right? Non-adaptation to cylinder, or over or undercorrection of cylinder just gives "blur" as a symptom, not "ghosting". Not much you can do about it, anyway, but use trivex and avoid extra peripheral blur from a PAL, and you've done that already.


Needing horizontal prism from a lateral heterotropia is a drag.
Ansiometropia is a drag.
Corneal dystrophy is a drag.


For all we know, any one or more of those three could cause her symptoms. We haven't even begun to address the lateral binocular problem and the problems that might be causing.

[optical24/7]

What level and why please.

Item No. ~ Snellen Acuity Level
6100 (1.0) ~20/20
6080 (0.8) ~20/25
6060 (0.6) ~20/30
6040 (0.4) ~20/50
6030 (0.3) ~20/70
6020 (0.2) ~20/100
6010 (0.1) ~20/200
60<1 (<0.1) ~20/300
60LP (LP) Light Perception
6000 (00) Total Occlusion (beige)


https://www.fresnel-prism.com/produc...clusion-foils/

Just a thought, but it could eliminate/reduce;

Binocular fusion issues, off axis blurr issues, possibly the ghosting issue, the ansei issue and the elimination of the slab need. She may very well prefer clear mono vision over trying for binocularity. Cheap and easy to try with either the filter or trial frame.

What ever direction y’all go, I would cut the prism in the OD and throw the balance of what’s left in the OS. At least her good eye won’t have to deal with added LCA’s from the prism. As far as what degree filter, the least amount it takes to accomplish the goal. ( least amount for cosmetic reasons on the OS).

[Uncle Fester]

Update:

I made a pair of sv distance only glasses which proved the rx as written works well after wearing them for the last several weeks. She also has a current rx, past bifocal pair, made by my coworker which created double vision in the near due to lack of slab off. There are also multiple small oval frames of the same shape which allows for easy interchanging of lenses.

Well she brought them in yesterday with painters tape over the left lens segment saying this was working and could I change the left lens sv distance with the bifocal and put that sv distance lens into her now right only bifocal with the weaker add creating monocular near focus on each pair.

Very positive reaction! So it looks like through trial and error and her creative thought of monocular near found a solution that works for this challenging case!

She'll probably give up on any slab off as well as the trifocals but will need a driving only with dash focus for the add.

[drk]

wow. good job.

[Uncle Fester]

UPDATE:

A happy ending!

Dispensed yesterday and it is working well.

Thanks again for all the support and suggestions.

Optiboarders RULE!!!

[drk]

So the key was:

Allow binocular distance vison.
Penalize one eye at near to avoid diplopia by not giving an add power.

Right?

[Uncle Fester]

So the key was:

Allow binocular distance vision.
Penalize one eye at near to avoid diplopia by not giving an add power.

Right?

Oopps wrong thread!

belongs to my aniso prism thread: