I have anisometropia and (probably) a dumb question for the experts

[MikeAurelius]

Had it since 6th grade (lo these many years ago), went from perfect vision to needing:

R: -1.25 Sphere
L: -3.00 Sphere

in about 6 weeks. Wore the dorkiest glasses, plus had braces, I was the 4 eyed-tin grin LOL...but I digress.

My Rx has long since stabilized and when I hit 40, I was put into bifocals.

Currently, my correction is:

R: -1.50 sph
L: -3.50 sph

My question: is there a good reason why my +1.50 add was not prescribed as a split add? For example +1.50R/+3.50L?

This is always something that I've been curious about and just wondering if this is something that is routinely done or not. I asked my OD and he just shrugged it off and told me I was overthinking it.

[Jacqui]

You're overthinking again. Believe your OD

[MikeAurelius]

Oh, I do believe him, I'm just looking for an explanation. I understand magnification/minification quite well, but it doesn't fit with my understanding of the process.

The right eye corrects to plano, but the left eye corrects to -2.00 at reading distance. I can understand not wanting to split add powers for minor differences in spherical correction, but not a 2d different. Thoughts?

[Jeff Trail]

you are trying to mix apples and oranges here....effective power for your presbyopia is plano in the right and -2.00 in the left.. as the crystalline lens becomes less flexible, as you age, you lose the ability to "refocus" at certain distances.. one of the advantages a myop has as the lose that ability you introduce "plus" power... a slight myop has a time period in that process where they can actually get by with out any glasses to read... but in your case where you have a difference of power you need compensated power in the -3.50 side ..and effectively you are plano in the -1.50 side.. since wearing a monocle is out of fashion it is easiest to wear a set of lens set for your presbyopia and myopia...

If the OD had split the power as you wondered, you would be under refracted for reading in one eye and over refracted in the other.. as you tried to converge it would appear blurred.. if you occluded one eye and held a piece of paper to read.. you would have to move it closer.. occlude the other and you would have to move it another direction..

You are trying to make something that is complicated to easy :-) not the other way round..

Jeff "make it up as you go along...less stress"Trail

[Wes]

Had it since 6th grade (lo these many years ago), went from perfect vision to needing:

R: -1.25 Sphere
L: -3.00 Sphere

in about 6 weeks. Wore the dorkiest glasses, plus had braces, I was the 4 eyed-tin grin LOL...but I digress.

My Rx has long since stabilized and when I hit 40, I was put into bifocals.

Currently, my correction is:

R: -1.50 sph
L: -3.50 sph

My question: is there a good reason why my +1.50 add was not prescribed as a split add? For example +1.50R/+3.50L?

This is always something that I've been curious about and just wondering if this is something that is routinely done or not. I asked my OD and he just shrugged it off and told me I was overthinking it.

Oh, I do believe him, I'm just looking for an explanation. I understand magnification/minification quite well, but it doesn't fit with my understanding of the process.

The right eye corrects to plano, but the left eye corrects to -2.00 at reading distance. I can understand not wanting to split add powers for minor differences in spherical correction, but not a 2d different. Thoughts?

Im gonna try to make this a little simpler than it is, so those of you who have more in-depth knowledge, don't butcher me.
The corrections are to focus light back on your retina. One eye is +1.5 D "too strong" the other is +3.5D "too strong" (not exactly accurate, but considering the question). Thats why you use opposite minus lenses to adjust the focus.
Light coming from near objects has negative vergence. Light from an object 1 meter away has 1 diopter of negative vergence or divegence. Light coming from an object 40 cm away, which is reading dist for most, has a negative vergence of -2.5 D (the reciprocal of .4 meters).
Your right eye is essentially a +1.5 uncorrected, and since that also equals your add, you can just take the glasses off and see up close with it. The left, however, being essentially a +3.5 uncorrected requires you to wear a -2.00 for near vision to get the required +1.5D.
As far as image size/fusion issues, they're more related to whether or not your visual error is refractive (corneal/lenticular) or related to axial length or a combination of the two.
Mike, this is why we ask you to leave the "Optician" questions alone.

[MikeAurelius]

LOL...and this is more information than I had EVER gotten from 4 OD's over the space of 20+ years!!!

I get patted on the head and told to not worry about it. I'm not worrying, just trying to figure out WHY. One of them did volunteer that he'd never fly in a plane with me unless I was wearing contact lenses, especially a tail-dragger.

Wes - if I left questions like this alone, I'd never learn anything new! And I have learned something new today. Thanks to you all.

[Wes]

NP Mike. Oh, and I meant don't answer the noobs if you're not sure, cause they don't know the difference.

[harry888]

Mike,

Do you find near better with no Rx? That's when I'll do split adds.

Harry

[MikeAurelius]

Harry, I ALWAYS take my glasses off to read, in fact, I'm almost to the point of going back to SV for my every day eyewear, and save the bifocals for in the car. I don't seem to have a size/focus problem for reading, but for computer work, I think I'm going to do a reader but I've got to figure the distance for the correct add power. (I even take my glasses off to eat!)

[chip anderson]

Mike:
When reading with glasses off, you are seeing two different sized images at probably two different distances. In theory at least you should find it less tireing to read with glasses on.
Now the good news. When you gits a bit older the right eye with glasses off will be focusing at computer distance, left will be focusing for reading distance. Still lacking steriopsis and ballanced image size. But funtional (if your really like functioning as a one-eyed man). If only one eye is in focus at a given distance, you function as a one eyed man.

Leave the glasses on for everything and you should be happier and less fatiqued.

Chip

[fjpod]

As if you need more help...let me take a crack at it. When you are fully corrected in each eye for distance, you are "normal", When you go to read, each eye theoretically requires the same add for near...regardless of what the original refractive error was.

That being said (...don't you just hate that phrase), many myopes such as yourself, love to read without their glasses when they become presbyopic, and yes you are theoretically reading under less than optimal conditions when you do this, but the visual system is very elastic and adaptable, and a full field is better than any progressive channel any day of the week.

A little off the subject, but the fact that you love to read without your glasses...is why I hate to recommend LASIK to people like yourself. You are habitually used to seeing well up close...get LASIK and that is gone.

[FVCCHRIS]

Hey Mike, just do what we all do- You think you need something different? Pretend your ordering from an On-line optical supply house, fill in the boxes the way Dr. Mikey wants it and prove those silly OD's wrong(as usual) !! .......................he-he, snicker, etc. :hammer:

[DragonLensmanWV]

Gee, Mike - less than two diopters? Most of my customers wouldn't notice that much. You should try what I had to do when I underwent cataract surgery. After the first one was done, I has 13.50 D of aniso going. Of course there was no way to use both eyes at the same time, so I had a vinyl patch cut so I could switch it from eye to eye depending on which ne I wanted to use at the time.

[harry888]

mike,

I'd probably give you unequal adds by about +0.50 given that you take your specs off to read and seem to like the range it gives you.

Harry

[MikeAurelius]

Actually, Dragon, I just closed an eye last night while I was reading, and yes, my left eye was NOT focusing (DUH! LOL!!)...so, yeah, I'm gonna make me some readers. And wear them all the time while reading.