Prism trouble shooting question

[hrivas302]

I'm trying to pick some brains for help on troubleshooting my new Rx.

I just received my new glasses from my job (SVS vision) and I have having some difficulty adjusting to my new Rx. And we are scratching our heads with the troubleshooting.

Old Rx
OD -0.25-0.25x 70 2BI ADD 1.00
OS -0.25-0.25x 120 2BI ADD 1.00 Polycarb + AR

New Rx
OD -0.25-0.25x 70 4BI ADD 1.25
OS -0.25-0.25X120 4BI ADD 1.25 high index 1.67 +AR

my Old Rx mono PDs of 32,32 which we used on my new pair due to not having any problems on previous 2 PALs. However while trouble shooting pupilometers measure me at 33.4,34.5.

Lensometer checks out, Seg heights check out, and Good fit (drilled rimless frame if that matters) But I am getting a really noticeable 3D effect, particularly with Blue Lights (LEDs etc), I've had this effect with reds for over a year now and just got used to it that I ignore it, But with these blue lights its really throwing me off. Also my distance is not as clear, I actually feel like like I am wearing a plus lens but lensometer reads ok. No headaches or pulling that I am aware of. it actually feels quite comfortable

Unfortunately the suits upstairs are kinda anal when it comes to employee remakes so we cant do too many of the "well let's try this and see how it works"

Any ideas ???

[drk]

Four more prism diopters is a lot. Why?

[hrivas302]

Eyes drift outward and I was getting headaches without the prism, when I look at things out in the distance objects go in and out of focus. I guess I liked it in the chair when he upped it from 2 to 4 but in my actual glasses I'm struggling with it. It feels comfortable for the most part but visually the I'm struggling with the 3d effect from lights and distance is not as sharp

[Robert Martellaro]

Probably caused by chromatic aberration. Because the prism is prescribed, the aberration shows up in the straight ahead gaze as well as the lateral gaze. Switching to a higher Abbe value lens material, Trivex or 1.60 for example, will reduce the symptoms.

https://www.2020mag.com/article/chro...tion-rxpertise

Hope this helps,

Robert Martellaro

[Kwill212]

Why 1.67? Makes no sense(neither does poly for this). Low abbe value is the obvious problem here as Robert said.


Might want fix your PD while you are at it. If your PD is really 68 and your making them at 64 you are neutering the corridor. Might not be terrible now with a low add, but it's going to get worse as your add goes up. Also you should be moving the PDs out to compensate for the base in prism. So if your PD is 68 you should really be pushing the PD out to 70.5.

Also what symptoms were you experiencing necessitating the jump in prism?

[NAICITPO]

Why 1.67? Makes no sense(neither does poly for this). Low abbe value is the obvious problem here as Robert said.


Might want fix your PD while you are at it. If your PD is really 68 and your making them at 64 you are neutering the corridor. Might not be terrible now with a low add, but it's going to get worse as your add goes up. Also you should be moving the PDs out to compensate for the base in prism. So if your PD is 68 you should really be pushing the PD out to 70.5.

Also what symptoms were you experiencing necessitating the jump in prism?

[drk]

Hey, Kwill:

On that prism thing, do YOU do it, or does the lab do it? I.e., how do you safeguard against "double compensation"?

[Kwill212]

I don't know of any lab that would do this on their own. You order a the adjusted PD.

[chamilun]

chromatic aberration. why are you in 1.67? I'd go straight up CR-39 and back the prism off 1D in each eye

[hrivas302]

It's a drilled rimless frame, the doctor bumped the prism up from 2 to 4 in the chair and it felt fine in the trial frame

[chamilun]

It's a drilled rimless frame, the doctor bumped the prism up from 2 to 4 in the chair and it felt fine in the trial frame

switch to trivex. I'd still lower the prism. may have some aberration still but will definitely be improved

[hrivas302]

I went with 1.67 due to my manager and coworkers recommendation. It's a drilled rimless frame ( I know not the best choice), I wasn't complaining to much just a little fatigue when reading at distance and near. Doc bumped it up and it felt fine while I was in the chair

[Kwill212]

switch to trivex. I'd still lower the prism. may have some aberration still but will definitely be improved

You'd lower the prism without any patient history, or exam? Sound doctoring there.

[Kwill212]

I went with 1.67 due to my manager and coworkers recommendation. It's a drilled rimless frame ( I know not the best choice), I wasn't complaining to much just a little fatigue when reading at distance and near. Doc bumped it up and it felt fine while I was in the chair

So this is Vision Works? America's Best? Somewhere that the manager trained all the employees and the manager doesn't have any ophthalmic optics training.

[chamilun]

You'd lower the prism without any patient history, or exam? Sound doctoring there.

yes. starting to see your personality. you canhelp, or move on. your choice

[chamilun]

and kwill. one of the best opticians I know works for..............Costco. Judging americas Best or visionworks etc. you never know who was helping them
at any time

[Kwill212]

yes. starting to see your personality. you canhelp, or move on. your choice

I prefer to help by asking questions and sorting through the problems than shotgun scatter, but to each their own.

and kwill. one of the best opticians I know works for..............Costco. Judging americas Best or visionworks etc. you never know who was helping them
at any time

Your unwillingness or inability to apply comments to their obvious context is ridiculous.

[Elvis Is Alive]

Best place to start IMO it to have the amount of prism prescribed rechecked by your OD.

Trivex would be the best material choice if switching frames isn't an option. I assume that 1.67 was recommended to you cosmetic reasons. I' would make sure you use the accurate PD as well.

If you aren't aware, generally speaking, the thinner (higher the index) the lens material is the less optical clarity it will have (lower ABBE value, more reflectivity, etc)

Plus, 1.67 isn't an ideal material for drilled rimless. It is more brittle, and has less tensile strength. it will chip and break more easily.

[Kwill212]

Plus, 1.67 isn't an ideal material for drilled rimless. It is more brittle, and has less tensile strength. it will chip and break more easily.

1.67 is a perfectly fine material for drilled rimless. It's second only to Trivex for drilled materials. Sure it's not impervious to basically everything like Trivex(which is what I use for 95%+ of my drill jobs.) But to say 1.67 isn't ideal for drill jobs is selling it short.

[Elvis Is Alive]

i'll disagree there. If the lens is too thick for Trivex or the more drillable version of 1.60 (MR-8 i think) then I'm not recommending a drill mount frame. I'll use 1.67 for full rim frames but not drills.

[Kwill212]

Are you sure you aren't thinking of 1.74(very brittle, prone to chipping)? 1.67 and 1.60 are both virtually identical as far as durability in drilled frames.

[Elvis Is Alive]

No, I am aware of the supreme brittleness of 1.74.

It has more to do with me. Personally I don't like fit a drill mount in very many RX's above 4 diopters unless it is a small eyesize or the decentration is quite small.

I'll have a long conversation with someone if they insist on a drill with high plus/minus.

[Kwill212]

No, I am aware of the supreme brittleness of 1.74.

It has more to do with me. Personally I don't like fit a drill mount in very many RX's above 4 diopters unless it is a small eyesize or the decentration is quite small.

I'll have a long conversation with someone if they insist on a drill with high plus/minus.

Welp, we are clearly on very different optical journeys. I just ordered up a +9.00 rimless(and have done up to -16). That is part of the beauty of rimless, full control of the eye size and decentration.

Regardless. Strictly talking materials, MR10 and MR8 both have great tensile strength for drill mounts.

[luka]

Excuse me as it's my first reply. If reducing the prism is absolutely not an option based on the optom, the trivex would be the way to go to reduce the transverse chromatic aberration.

Based on the article Robert linked, for a plano polycarb lens with 2Δ, we have a colour spread of about 0.067D. Going to a 4Δ lens in 1.67 we have about double, or 0.125D, which is the problem. 1.6 won't solve the problem (0.111D @ 4Δ) but trivex gives us only 0.093D, only 1.5x more than in the poly lens. So assuming everything is pretty much equal between the old glasses and the new except for the prism, trivex would be the choice to go for if you're doing a remake.

Cosmetically it'll be thicker yes. Sometimes I discuss with patients and get the lab to narrow drill mount lenses by a mil or two which could save you some of the nasal thickness. I would agree with Kwill about ordering the 70.5 PD.

[drk]

Ooo. Good first reply.

Don't make it your last!




Here's my stupid easy take.

poly and 1.67 have the same optics and general usefulness. It's "poly" and "ultra-poly". That's the way I roll.

(I now avoid 1.74)

trivex is a mid-index tweener between basic old CR-39 and poly/ultra-poly used for special circumstances. (And 1.6 is polycarb that went to the gym and firmed up it's abs a little, but it's still a high index like poly.)