ansiometropia and RX

[kaypaula]

Hi all,
I have a pt coming in to see me about glasses. His RX:
OD-7.00-3.75X155
OS-1.50-1.25X105 ADD +2.000
Wanted some opinions on lens type. I was thinking isokonic may help with image size. Any other opinions would be great. Also, I don't think he's going to get a MF of any type, pretty sure he wants to stay single vision. He is an RGP wearer so this is back up only as his VA probably won't be great with them to begin with. Probably about 20/40 OD corrected and 20/25 OS. Not too bad but much better in the RGP's.
Thanks
P

[Robert Martellaro]

Hi all,
I have a pt coming in to see me about glasses. His RX:
OD-7.00-3.75X155
OS-1.50-1.25X105 ADD +2.000
Wanted some opinions on lens type. I was thinking isokonic may help with image size. Any other opinions would be great. Also, I don't think he's going to get a MF of any type, pretty sure he wants to stay single vision. He is an RGP wearer so this is back up only as his VA probably won't be great with them to begin with. Probably about 20/40 OD corrected and 20/25 OS. Not too bad but much better in the RGP's.
Thanks
P

Tell us about the habitual eyeglasses.

Iseikonic lenses will only be helpful if the client aniseikonic.

http://www.pacificu.edu/optometry/ce...niseikonia.pdf

[kaypaula]

Don't know about his habitual yet, I have a feeling he does not have a habitual pair, just relying on his OS. A DX of anisometropia is a good reason to look at Iseikonic lenses, to help with image size disparities, also to help a bit with lens thickness inequalities. Thanks for the powerpoint link. Looks like to be a good help.

[rbaker]

If we note the difference between the Rx for the OD & OS the subject is, by definition, anisoconic.

[MikeAurelius]

The big but here is: is there any lab that can process the required lenses to correct this, and further, will the patient actually wear them?

[Robert Martellaro]

Don't know about his habitual yet, I have a feeling he does not have a habitual pair, just relying on his OS. A DX of anisometropia is a good reason to look at Iseikonic lenses, to help with image size disparities, also to help a bit with lens thickness inequalities. Thanks for the powerpoint link. Looks like to be a good help.

Your welcome. A trial frame would offer some clues. I would strongly recommend talking to the prescriber before attempting to correct for aniseikonia.

If we note the difference between the Rx for the OD & OS the subject is, by definition, anisoconic.

Anisometropia.

Aniseikonia is possible, but not certain, or even likely. (to the extent that it must be treated with Iseikonic lenses)

[kaypaula]

A trial frame would offer some clues.


Yes, good idea!

I would strongly recommend talking to the prescriber before attempting to correct for aniseikonia.

Work in prescriber's office, not a problem. They are usually clueless about lens type though. They pretty much rely on the Optician's, as they should, for these types of things. Also, wouldn't he have image size problems regardless of DX? ..with this type of RX? Seems like a given.
Also, he IS going to go with MF. Here is what we have chosen:
Small round eyesize frame 44, Summit CD at 16 high, Good AR, Slab off (since he is going MF now), Highest Index I can get. I do believe the lab will choose different base curves to help offset the problems here.
I had an Iseikonic Lens done by HOYA once before, and also once at Walman so finding a lab to do this won't be a problem.









Anisometropia.

Aniseikonia is possible, but not certain, or even likely.

..

[optical24/7]

...... A DX of anisometropia is a good reason to look at Iseikonic lenses, to help with image size disparities, also to help a bit with lens thickness inequalities.... .

Actually an Iseikonic lens design will exacerbate the lens thickness and cosmetics. The basic principal of their design is to increase magnification in the strongest minus by selecting a higher than best form BC, increasing thickness and shortening the vertex (best done with bevel placement. OD in this case) You can also use differing indexes to some degree.

Then induce more mimification in the weaker lens by selecting a flatter than best form BC, reduced thickness and lengthening the vertex (OS in this case).

I agree with Robert about trial framing and talking to their Dr.

[Robert Martellaro]

Don't know about his habitual yet, I have a feeling he does not have a habitual pair, just relying on his OS.

So, no eyeglasses is the habitual, probably since day one.

Hint: No matter how hard you try, this client will probably take their eyeglasses off for near tasks.

Will the eyeglasses be worn five minutes a day, or five hours a day?

[Jason H]

I work for Luzerne Optical and we can fabricate iseikonic lenses. However, much like slab-off, I would wait till they demonstrate a need for it. Wait for problems to manifest themselves before you try to solve them.

[Robert Martellaro]

I work for Luzerne Optical and we can fabricate iseikonic lenses. However, much like slab-off, I would wait till they demonstrate a need for it. Wait for problems to manifest themselves before you try to solve them.

Right. Too much of the kitchen sink and you end up flirting with 'If it ain't broke, fix it 'till it is.'

[kaypaula]

So, no eyeglasses is the habitual, probably since day one.

Hint: No matter how hard you try, this client will probably take their eyeglasses off for near tasks.

Will the eyeglasses be worn five minutes a day, or five hours a day?

These will most likely be backup to his RGPs. So Im guessing an hour or so a day, if at all. Still, I want a product he can use.

[kaypaula]

Actually an Iseikonic lens design will exacerbate the lens thickness and cosmetics. .

More worried about visual comfort than cosmetics; wouldn't an Iseikonic lens help with image disparities? For instance and just pulling numbers out of the air for example purposes, his OD will have minification of 10% but the OS only 1%? Get what I'm saying? That's what I'm worried about. Not that one will be much thicker than the other. Of course I DO want them to LOOK as best as possible but optics first. Having said all that, I don't even think this guy is going to wear them at all! I was just hoping if he got a product he could wear, he would.

[Robert Martellaro]

These will most likely be backup to his RGPs. So Im guessing an hour or so a day, if at all. Still, I want a product he can use.

Understood. Emergency back up for driving when the CLs can't be worn, TV after CL removal in the evenings, etc.

Depending on the results from trial-framing and a consult with the doc, you might be headed towards SV distance (OD balanced or full Rx), removed for near tasks.

If a multifocal is required, strongly consider segmented, although you might get by with a PAL if the vision is suppressed in the right eye, and there are not frequent close tasks. Consider biasing the PAL design towards the distance vision.

Chemestrie Clips with a power layer might be on the table for intermediate or near tasks also.

I wouldn't recommend a PAL for Iseikonic/bicentric lens design solutions.

This is very difficult scenario with results that are usually marginal at best. There are many possibilities depending if the client is binocular to varying degrees with spectacles, how often the eyeglasses are used, and what they are used for.

Keep the thread active and we'll try to help as best we can. Hopefully your client can stay in CLs with generous wearing times for the decades ahead.

[drk]

Martellaro is spot-on, as usual.

When designing iseikonic lenses, you can only modify the power and BC. In the case of anisomyopia causing aniseikonia (which hasn't been diagnosed, but let's go with it) all you practically do is order equal BC and CTs, anyway. Do that, at least. Modify the BC OD since the VA is poo poo.* Both CTs will be 1.5 automatically.

I would make this frame teeny weenie like a 42 round or better yet a 48 rectangle so he can do what Robert indirectly suggests: peek under to read.

This guy will be a hard core CL wearer (as all RGPers are) so they only need to work for several hours at a time.

Pray for cataracts.

[drk]

* Here's a toughie: Is it better in this case to fudge the BC in the higher power eye with the worse VA (is the dude post-retinal detachment, BTW?, or a cataract!) and hope he's less sensitive to being off corrected curve, or is it better to fudge the lower power lens because of less reduction in peripheral vision, despite it being the better acuity eye?

That's one for Darryl's Optical Lens Analyzer program...

[kaypaula]

* Here's a toughie: Is it better in this case to fudge the BC in the higher power eye with the worse VA (is the dude post-retinal detachment, BTW?, or a cataract!) and hope he's less sensitive to being off corrected curve, or is it better to fudge the lower power lens because of less reduction in peripheral vision, despite it being the better acuity eye?

That's one for Darryl's Optical Lens Analyzer program...

Here are his DX's

1. Keratoconus-stable od-order RGP CL for best VA and ansiometropia, px ed DVO CL 2. Chorioretinal scar od-px reports injury with cable, px ed si/sx of RD if occur RTC ASAP3. Pingueculum OU. Wear sunglasses outside.4. Dermatochalasis ou: not visually significant. Observe5. Myopia ou/Astigmatism ou/ Presbyopia ou-New Spx Rx given (back-up), order RGP lenses for best VA , make appt when lenses arriveRGPs medically necessary due to Keratoconus and high ansiometropia

[4554lake]

Hi all,
I have a pt coming in to see me about glasses. His RX:
OD-7.00-3.75X155
OS-1.50-1.25X105 ADD +2.000
Wanted some opinions on lens type. I was thinking isokonic may help with image size. Any other opinions would be great. Also, I don't think he's going to get a MF of any type, pretty sure he wants to stay single vision. He is an RGP wearer so this is back up only as his VA probably won't be great with them to begin with. Probably about 20/40 OD corrected and 20/25 OS. Not too bad but much better in the RGP's.
Thanks
P

You are setting yourself up for a lot of headaches...I would go balance lens for OD and given rx for OS...after trial framing it and advising patient of what you're doing and why....This will be way less hassle and should work fine....

Whoever wrote the rx should have thought about the practical considerations of such a large discrepancy between the eyes and modified it accordingly....Either the prescriber doesnt know any better or was too lazy to do so.

[drk]

Kudos to your doc for excellent records.

[drk]

Oh...don't pray for cataracts.

For a cone, I think undercorrecting the worse eye is a decent way to go (assuming that the Rx is not already doing this).

You can undercorrect the more keratoconic eye (VA is still decent enough) by about 2.5-3D for a monovision effect, and reduce the lens power imbalance at the same time.

This would have to be trial framed, of course. The patient may reject it out of hand.