She doesn't want much, She just wants it all.

**DazeyReign** · 03-19-2015, 03:50 PM

I'm just asking this at this point because I just have to know if there is an equation that exists to accomplish this. Curiosity and Vanity being the inventors in this situation.

I have a patient that is -6.50 sph OD with Balance lens (NO vision) OS. She firmly believes that the OS eye, with no vision, is quite a bit smaller that the sighted eye. Now, I can see the difference but I think that it's something that she's been looking at her whole life and has made a much bigger issue than it is. (Being a woman, I know how this can work

)

So, glasses are being ordered in 1.67 and she wants to know if the balance lens can be made in a plus power to compensate for the difference. I have set her straight on the minification (<---Seems like that should be a word, I'm leaving it

) of her script vs what a plus lens would be and how that wouldn't work well, BUT... my question is -

Is there an equation that would give me the correct amount of minus for the other eye that would balance the aesthetic. Off hand, I'm guessing at maybe a -4.50; but this is flat out grasping at straws. And I think that for a proper equation we'd need eye size, etc. More info anyway, I'm just curious if it's possible, or been done.

Provided this is making sense, anyone have any thoughts?

**AngeHamm** · 03-19-2015, 03:55 PM

That is officially nuts.

**rbaker** · 03-19-2015, 03:57 PM

Forget equations and all of that. Merely remove the balance lens from her old glasses and slip in some trial lenses until she is happy. Voila

**CME4SPECS** · 03-19-2015, 03:58 PM

would this help?
http://opticampus.com/tools/magnification.php

**drk** · 03-19-2015, 04:02 PM

Maybe the minification from the right lens will do all the balancing you need?

**adreyyy** · 03-20-2015, 08:51 AM

Why don't you just put in the same RX on the OS since she has no vision out of it anyways? That would even it out, wouldn't it?

**Chris Ryser** · 03-20-2015, 10:40 AM

Originally Posted by rbaker

Forget equations and all of that. Merely remove the balance lens from her old glasses and slip in some trial lenses until she is happy. Voila

.............the response of the old school optician is the most perfect and reasonable.

**rbaker** · 03-20-2015, 11:57 AM

Originally Posted by Chris Ryser

.............the response of the old school optician is the most perfect and reasonable.

This is the procedure that I was taught at the feet of Roger Alton at the Monoplex Eye Department at American Optical in Southbridge Mass in 1970. It was the gold standard method of obtaining cosmetic balance of both eyes through a pair of spectacles acceptable to the patient. No math, no geometric optics formulas, no judgment calls (and errors) on the part of the fitter, just a few plus and minus lenses and a mirror.

What worked back in the day still works today!

**optical24/7** · 03-20-2015, 11:58 AM

There is no equation for " quite a bit smaller ". Math needs something more precise. Trial as rbaker suggests.

**Chris Ryser** · 03-20-2015, 02:10 PM

Originally Posted by rbaker

What worked back in the day still works today!

Optics has never changed its just done easier and when an odd problem pops up the new generation is lost.

Warren has been preaching that forever.

**DazeyReign** · 03-20-2015, 02:45 PM

The old school assumes an old pair of glasses that I don't have.

An equation exists without specific numbers - a times b = area of a rectangle. I plug in information once I have the key. Just looking for a key.

Luckily, patient has scientific sense of adventure and is allowing educated guess because she really wants to know! Thanks for input!

Personal note to AngeHamm - That's what I'm really trying to say.

**optilady1** · 03-20-2015, 02:50 PM

Subject change, do you normally have balance pt's sign a waver when you don't put them into poly/trivex? Or am I just still married to the optical chain train of thought?

**DazeyReign** · 03-20-2015, 02:59 PM

Patient is almost full time contact wearer doing a "super fun pair of glasses" (read - Larger 'Hip' lenses) for the few days she wears them. The whole job is - At Your Own Risk. And she knows.

In general, we operate along the lines you're describing.

**mervinek** · 03-20-2015, 03:51 PM

Originally Posted by optilady1

Subject change, do you normally have balance pt's sign a waver when you don't put them into poly/trivex?

I thought the same thing when I read it!

**Robert Martellaro** · 03-22-2015, 10:13 AM

Originally Posted by DazeyReign

I'm just asking this at this point because I just have to know if there is an equation that exists to accomplish this. Curiosity and Vanity being the inventors in this situation.

I have a patient that is -6.50 sph OD with Balance lens (NO vision) OS. She firmly believes that the OS eye, with no vision, is quite a bit smaller that the sighted eye. Now, I can see the difference but I think that it's something that she's been looking at her whole life and has made a much bigger issue than it is. (Being a woman, I know how this can work

)

So, glasses are being ordered in 1.67 and she wants to know if the balance lens can be made in a plus power to compensate for the difference. I have set her straight on the minification (<---Seems like that should be a word, I'm leaving it

) of her script vs what a plus lens would be and how that wouldn't work well, BUT... my question is -

To be clear, with the eyeglasses in place, the left eye looks smaller? Any chance that there is a ptosis in the left eye?

Later you said, "Patient is almost full time contact wearer."

Does she complain of different eye sizes when she's wearing the CLs also?

Is there an equation that would give me the correct amount of minus for the other eye that would balance the aesthetic. Off hand, I'm guessing at maybe a -4.50; but this is flat out grasping at straws. And I think that for a proper equation we'd need eye size, etc. More info anyway, I'm just curious if it's possible, or been done.

Probably the lens and magnification equations. Solving for spectacle magnification won't provide the answer- that's for retinal image size.

Before you balance with plus, make sure it won't cause any visual problems for the client- they may need the minus power for peripheral vision for instance. Consult with the prescriber if there are any doubts.

A prosthetic contact lens is another option.

**tmorse** · 03-22-2015, 02:08 PM

You can have your lab find a 'cull' lens within 80% power of the other eye, or use a spherical equivalent (S.E.)for a balance lens... Sphere + 1/2 cyl = S.E.

**Happylady** · 03-24-2015, 07:45 PM

You certainly don't want the balance lens to be plus- that would really look strange! I would make it about a -4.00.

**Robert Martellaro** · 03-24-2015, 08:30 PM

Originally Posted by tmorse

You can have your lab find a 'cull' lens within 80% power of the other eye, or use a spherical equivalent (S.E.)for a balance lens... Sphere + 1/2 cyl = S.E.

I doubt we'll get enough help increasing the size of the left eye with 80% of the power, if the back vertex distance is short, which it should be for a client with monocular vision. Plano might be a good starting point, and easy to evaluate simply by removing the left lens.