Mono vision glasses?

[ilanh]

Regarding why I undercorrect the "near eye" for distance: I noticed after a while that even though post-lasik I was able to correct both eyes to 20/20 with monovision glasses, many patients confessed that they never wore their glasses when driving at night. These were very basic spectacles: essentially plano in the distance eye, -2.25 in the near eye with an AR coating. When I questioned them further they admitted that the glasses caused them "strain or discomfort." This is strange because those same people claim that they experience no strain with their 20/400 eye (their -2.25 near eye) driving at night. I was baffled about this for a long time but was concerned about safety issues regarding monovision night driving. Ultimately, I began undercorrecting the near eye such that their BCVA was about 20/40 (instead of 20/200-20/400). This seems to have solved the problem for now. I suspect that anisometropia may have been the issue or perhaps that lasik creates islets of multifocality on the cornea that does not respond well to a high powered myopic correction.

[Dave Nelson]

I still suspect an eikonic imbalance perhaps exacerbated by pupil size, since the specs are worn mainly at night. This could explain the complaints of discomfort. Reducing the rx may be effective if you are reducing it to the "comfort threshold," while removing the spectacles increases the disparity to the point of suppression.

[gunner05]

Actually, I fit mono-shooting glasses all the time. It's a little niche that I've found for myself in the area which no one else here really knows how to fit well. Pistol shooters have a hard time once presbyopia sets in and all of the local law enforcement officers know to come to me to get fixed up once they start having problems. It is always fun telling someone "well, you'll have to bring your gun with you when you see your OD so they can get the correct distance between your eye and front sight." Learn how to fit them, educate yourself on the varieties of tints used by competitive shooters (yellow, amber, red, G-15, etc) and you can set yourself apart from other opticals. I just hate that I'm restricted on my lenses for this since I work retail, but that's totally different.

The main problem that I've encountered is the induced prism due to the difference in Rx between eyes. For most people, it's not that bad, but some have problems that they can or can't adapt to.

[fjpod]

I think we are mixing a little apples and oranges here. (no pun intended, orangezero). To me, monovision spectacles are not what you prescribe over monovision LASIK or CLs. These are monovision compensating spectacles. I prescribe them all the time.

In my mind, monovision spectacles are glasses that are prescribed where the non-dominant eye is corrected more for near. Some patients come in asking for this, not because they have had LASIK or CLs, but because they just don't want multifocals. I generally don't like to do this very much, because of greater problems with image disparity, vertex, etc. Keep in mind though, plenty of people walk around with uncorrected anisometropia (like one eye plano, and one eye -1.25) and they are as happy as a lark.

[npdr]

I often use "compensater" spectacles as well, primarily for night driving, but rarely over 1.5 D since I virtually never use more + than this on the contacts in the first place. I have also noticed, to my surprise, that some people who are completely occluded monocularly while looking through a phoroptor are often completely unaware of it.

Retinal rivalry.

[npdr]

Regarding why I undercorrect the "near eye" for distance: I noticed after a while that even though post-lasik I was able to correct both eyes to 20/20 with monovision glasses, many patients confessed that they never wore their glasses when driving at night.'...

I think many ECP ("eye care providers") may prescribe best vision glasses whether anisometropic or not just to be self assured that the patient has best vision when operating a motor vehicle. In other words, a professional liability defense.

In reality anisometropic corrections are tricky. Anisometropic at the corneal surface is different at the spectacle plane (12-14mm away) Where a patient may tolerate anisometropic spectacles, they may tolerate it in contact lenses or in residual refractive outcomes. I believe or I suspect that correction image size dfferences for each eye are more critical than previously thought.

[chip anderson]

Back in the pre-implant days, we had many patients that while we could correct the aphakic eye to 20/20 we would have to under or over correct to 20/30+or- with contacts to prevent diplopia due to image size or ballance distortions in the spectacle corrected fellow eye spectacle.

In a few other circumstances we could get the aphakic eye to 20/20 spectacle (due to magnification at macula) and only 20/30 contact. We would usually feel that 20/30 with same in most excursions from center was much better than 20/20 central and all the distortions etc. peripherally in spectacles.

Still don't see a reason for monovision in spectacles except possibley for a unilateral aphake. I do understand spectacles that bring the surgically or otherwise imballanced patient to best corrected va both near and far, butt then this isn't monovision glasses this is glasses to correct the problems of monovision.

Chip

[sharon m./ aboc]

Thanks to everyone that gave their input on this one. We have a patient that is getting mono specs. She is a first time presbyope that didn't like the progressives we made and can't wear contacts because Colorado has no humidty to speak of. She wants lasik but can't decide if she wants to do mono lasik because she can't wear contacts. Any how we tried a regular progressive and a short corridor progressive and she wouldn't even try to get used to them. I used to work for an O.D. that said mono glasses don't work because of the vertex distance. I don't think it's going to work and I think she needs a flat-top, but she's only 40 so she didn't want those either. Oh well, if you can't get used to progressives with a +1.50 then you're probably not going to be able to get used to these either. Right?
Happylady, What ever happened to your lady with the mono specs?

[gunner05]

Thought about a blended seg, maybe? Just another option if this doesn't work out.

[chip anderson]

How about a plain old ordinary st bifocal. One need not go high tech, high expense for a short term experiment with the odds against it in advance.

[Happylady]

Happylady, What ever happened to your lady with the mono specs?

I fit her with progressives, not mono glasses. When I ran into her where she works she told me she was having trouble getting used to her glasses, but I think it is because she isn't wearing them very much. I told her she needs to wear them more to get used to them and to come and see us. I haven't seen her come in yet, though.

Keep us updated on your patient with the mono glasses. :)

[macularry]

HappyLady,

I will often do a spec Rx for my monovision patients over their contacts. It usually comes up when they spend more than an hour continuously on the computer. Monovision is great for casual use, but when someone sits at the computer for a significant amount of time, the imbalance can cause headaches and eye strain. I like to trial fram the Rx in the office and let them sit at a computer. They will love for the extra effort.

Most doctors don't like to take the time to compute the prescription. I became tired of doing the calculation and I made a computer program that will do all the work for you. You only have enter the person's age, height, computer monitor distance and their general use Rx and contact prescription. It will even compensate for vertex distance.

If you would like to use it, shoot me an email:
DrLarryTarrant@aol.com

[sharon m./ aboc]

HAPPY "L''...................... Just as I suspected the lady with the mono specs (not over contacts) hated them... She's going to get lasik . I think in both eyes and then she'll be strapped to reading glasses until the end of time. I'd like to ask you something else.... I wear mono vision contacts and progressives and I think your rx is very similar to mine. Since I wear my contacts most of the time when I wear my progressives I can't see as well out of the reading area in my "dominant" eye. I wonder if you have the same experience and if my brain is just so used to using that eye for distance only that the plus power just seems useless in progressives. Anybody have any imput on this?

[Jubilee]

We actually have 3 patients who currently wear monvision glasses as backups to their contacts and love them that way.

[drk]

Interesting discussion.

Group one: anisometropes
Group two: isometropes
Group three: monovision patients

Anisometropes more often than not do well with refractive imbalances because they "were born that way". They've adapted. As mentioned, a plano/ -1.25DS will be happy most the time uncorrected. A +1.00/+3.00 will be happy most of the time in +1.00 DS OU. What these folks don't do well with is FULL correction!

Isometropes, on the other hand, do not like to have induced refractive imbalances, as a general rule. Looky, the monvision success rate is generous at 50%, and that's factoring in all the minor +1.00 mono fits.

The success rate is going to go way lower than that when you make the imbalance at the spectacle plane, with the resulting image size difference, and the prismatic imbalance off-center. Why do this when better alternatives exist?

Monovision patients are isometropes that have been iatrogenically turned into anisometropes. They're a weird breed. They can tolerate more than expected, because either their system is plastic, or we've plasticized it. Can they wear distance or near compensating specs? Oftentimes, but it's still difficult. I think Ilan is right: give as little plus or minus as you can.

So, to the original thought: monovision spectacles in lieu of multifocals?
Maybe, maybe, on adapted monovision patients, but again: "Why"?



"...To boldly bold where no man has bolded before..."

[sharon m./ aboc]

DRK< Yes, I've seen od's back-off a little on one eye...a half a diopter at the most but to make one a single vision lens and the other a distance lens. I don't see how anyone could walk around much less drive or take stairs. It is so disorienting. And I'll ask it again if you can't get used to progressives how do you get used to these?

[sharon m./ aboc]

We actually have 3 patients who currently wear monvision glasses as backups to their contacts and love them that way.

When you say "backups to their contacts" do you mean 'over' their monovision contacts or 'instead of' their contacts? I guess it depends on the RX as well as the person. I don't see how anyone could benefit from the latter.

[Jubilee]

Yesterday I dispensed a pair of monovision glasses to be used as backups and her evening at home pair. We put her in progressives and in straight tops in the past, but last year she said she would rather have monovision in the glasses. We warned her of potential issues, but when she put them on, she thought they were better than any of the other types of multifocal correction we have done with her in the past.

We don't have very many of them, but I can name at least 2 others besides her that we have done this with.

Cassandra

[sharon m./ aboc]

WOW, It takes all kinds doesn't it?

[Happylady]

HAPPY "L''...................... Just as I suspected the lady with the mono specs (not over contacts) hated them... She's going to get lasik . I think in both eyes and then she'll be strapped to reading glasses until the end of time. I'd like to ask you something else.... I wear mono vision contacts and progressives and I think your rx is very similar to mine. Since I wear my contacts most of the time when I wear my progressives I can't see as well out of the reading area in my "dominant" eye. I wonder if you have the same experience and if my brain is just so used to using that eye for distance only that the plus power just seems useless in progressives. Anybody have any imput on this?

I just got some new Definity Short progressives. My distance is -2.25 -.25 in both eyes with a +2.25. I don't notice any more problem reading through my right eye in my progressives then I do with my left eye. Of course, I don't have any plus power in my glasses. The reading part is almost plano. I switch between my mono vision contacts and glasses easily.

I do wear a -.50 in my left contact so my close vision isn't quite as good as with my glasses(or without anything). Sometimes I use readers over them for extremely fine work.