The Pros and Cons of Mini Monovision

It was a retrospective single-institution cohort study showing patients with pseudophakic single-vision that were significantly older when they received their cataract diagnosis (72.7±7.4 years) than those with pseudophakic monovision (69.3±6.2 years) and those who had not undergone surgery (69.4±6.9 years, P <.001). After cataract surgery, 175 (9 pseudophakic monovision, 166 pseudophakic single-vision) patients had a documented fall. The mean number of falls was not significantly different between patients with pseudophakic monovision and patients with pseudophakic single-vision. When the researchers controlled for age, sex, and preexisting myopia, they found increased age at time of cataract surgery significantly increased fall risk after surgery (HR=1.05 P <.001).

"After being adjusted for age, sex and preexisting myopia, the data revealed no impact of pseudophakic monovision on fall risk in elderly patients. However, the pseudophakic single-vision group may face a disadvantage over the no-surgery group that explains the increased fall risk. The pseudophakic single-vision group had a significantly larger proportion of patients with a fall...These findings suggest that perhaps the residual accommodation in cataract patients who have not undergone surgery may potentially protect against falls, because the ability to focus, although greatly diminished, is still retained in phakic cataract patients but not in pseudophakia."

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in other words ability to focus closer whether due to retained accommodation before surgery, or due to monovison after surgery reduced the risk of falling.

The article itself wasn't published until February 2023. It's in the Canadian Journal of Ophthalmology, which doesn't appear to be available online without payment. If someone has access to the article itself, it would be interesting to know, for example, the degree, or degrees, of monovision of those in the study as a whole vs those with monovision who had a fall.

In the original publication, they reported a total of 13,385 patients were included in the study, of which 1.8% had pseudophakic monovision, 21% had pseudophakic single vision and 77.2% had not undergone surgery. When the researchers looked at the documented falls after cataract diagnosis, they found that pseudophakic single-vision patients had the highest fall rate of 7.9%, followed by no-surgery patients (5.9%) and pseudophakic monovision patients (5.8%). The overall rate of falls post-cataract diagnosis was 6.4%.

The actual underlying cause of the results is assumptive or speculative. This is an observational trial, so only outcomes over time are reported laying the foundation for a potential prospective study that could definitively concluded differences in interventional approaches. Retrospective cohort studies are not a particularly strong stand-alone method, as they can never establish causality. This leads to low internal validity and external validity.

The findings make common sense. That is good enough for me. I have no reason to go out of my way to dispute the findings of the study.

Mini-monovision has been done successfully for decades, and many people have it naturally. There is actually quite a bit of overlap between the eyes. When I watch a big screen TV at 8 feet or so both eyes are being used. Even when driving I can see the dash clearly with both eyes . I have had it for nearly 3 years now, and am quite happy with it. And one can correct it to standard vision by just putting on a pair of prescription glasses. I have them, but never use them as vision is much more natural with no glasses.

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The big downside is for ophthalmologists. There is no extra money in it as it uses standard monofocals that are fully covered by most insurance and public healthcare plans.

Many people have mini monovision and love it, myself included. I used premium lenses (Vivity) but that is not necessary either. It was my choice and it works great for me. And yes, the two eyes together provide good binocular vision. At all distances. Even if one image is a bit blurry, that does not mean one eye is under strain.

Laurie

I'm not aware of any studies showing the percentage of ophthalmologists who discuss monovision, mini-, micro-, or otherwise, with their patients. But in the United States, ophthalmologists who follow the Cataract in the Adult Eye Preferred Practice Patterns of the American Academy of Ophthalmology should "Explain advantages and disadvantages of intraocular lens (IOL) options, including astigmatic, multifocal, extended depth of focus, accommodating, postoperatively power adjustable, and monovision IOL alternatives, to reduce the patient’s need for spectacles or contact lenses after surgery."

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My own experience doesn't shed light on this question because I brought up my interest in mini-monovision near the outset of my conversations with the three surgeons I've seen. All were receptive. The second surgeon volunteered that he wears contact lenses that give him mini-monovision.

Laurie, what is the difference in refraction between your eyes?

I am also going to put Vivity on the first eye next week, according to the calculation it turns out -0.7D, and I want to do plano on the second eye.

I was forced to experiment on myself with monovision and I did not like the result. In my right eye, the cataract is longer and stronger, and for the computer this eye is already useless, everything is blurred and doubled, I see better with one left than with both eyes. Both eyes see poorly in the distance, the difference is small.

But I noticed that the left working eye began to get more tired, by the evening he also hardly sees the text on the screen. I have been sitting at the computer for more than 30 years for 10-12 hours every day (and even more on weekends), but when two eyes worked, it was easier for me. That's why I want to put Vivity so that two eyes work at the computer with a slight shift to myopia on one for smaller text. For vivity, more than -0.7D is not necessary, 0.5D is obtained due to EDOF and we get the same -1.25D as recommended by Ron.

"For vivity, more than -0.7D is not necessary, 0.5D is obtained due to EDOF and we get the same -1.25D as recommended by Ron."

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The extra depth of focus provided by the Vivity is just over 0.5 D. To get the standard -1.50 D of myopia for mini-monovision good close vision you would have to offset it by -0.90 D to -1.00 D. It is also important to consider what the spherical equivalent (SE) will be which includes the astigmatism effect. Since I wrote the original post, I have had my eyes checked again. According to this last refraction my near eye is at about -1.60 D SE. The original target was -1.50 D.

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Also keep in mind it is risky to target exactly plano in the distance eye. A more conservative target to avoid going positive, with a loss of near vision, is to target -0.25 D.

My right eye is -1.0D and my left eye is -0.25D. Minimal astigmatism in the left (-0.25) and none in the right.

My right eye is in best focus from about 8 inches to 5 feet, while in my left eye, good focus starts around 3 feet. Good binocular vision.

This combination works very well for me. It is great for reading and computer work. For night driving I wear distance glasses, it's just safer. However, I don't have any particular need for (or love of) night driving. And I can get by without glasses if needed (unlike before the IOLs).

My doc was not particularly chatty about lenses, targets, side effects and so on. It seems that most doctors don't provide half the info that we can learn from a forum like this. However, I did fill out a survey about my lifestyle, hobbies, etc. and after a discussion he recommended. Vivity lenses and to stay myopic, like I was before cataracts (-2D to -3D range). After my first eye was done, I had read a lot about monovision and I requested to have a little more distance for the second eye.

While I would say that we didn't have extensive conversations, this opthalmalogist was a highly rated doctor in a well known office, and he got a good result. Or maybe I was just lucky. After all, your own eye measurements affect where a specific lens will ended up target-wise, and there's nothing to be done about that.

"after a discussion he recommended. Vivity lenses and to stay myopic, like I was before cataracts (-2D to -3D range)."

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Wow! It sounds like you made a very good choice to take charge of the process. Using a Vivity at -2.0 to -3.0 D in both eyes makes zero sense. The extension of depth of focus will be at a distance where you could not have used it, and you would be still stuck with eyeglasses for distance.

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You were very fortunate to have ended up with -0.25 D and -1.0 D. That is perfect for a full range of vision with the Vivity lenses in a mini-monovision configuration.

So -0.25D on Vivity only gives good focus from 3 feet? They also promise in their advertising from 18 inches with plano.

3 feet should also give monofocals, is it worth taking Vivity then (and the question is not the price, but other disadvantages of MF). I would be happy to pay five times more, but get the vision of a 20-year-old, or even my 20-year-old myopia, but this is impossible.

I have a fairly large astigmatism in my left eye 2.5D, I want to make it near eye, anyway, maximum clarity will not work even with toric Vivity.

And the right eye still wanted to make as close to plano as possible, but in your experience it turns out that for a computer you need to have more margin, about -0.5D for 2 feet.

"I have a fairly large astigmatism in my left eye 2.5D, I want to make it near eye, anyway, maximum clarity will not work even with toric Vivity."

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Actually that amount of cylinder (astigmatism) is not that large and should be easily handled by almost any toric lens, including the Vivity. That assumes you are talking about predicted residual astigmatism after natural lens removal. This is the number they will give you after measuring your eyes, and is not taken from your pre surgery eyeglass prescription.

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Correcting less cylinder can be more difficult if it is in the -0.75 D range. The only common lenses that can go that low are the AcrySof IQ torics. The newer Clareon one do not go that low. The B+L enVista can go down to about -1.0 D.

Sorry, I did not express myself very well. My myopia was in the range of -2D or -3D before the cataracts set in. I was just trying to give a picture of my previous level of myopia. I've read the stories here of people with much worse eyes and maybe their experience would lead them to make different decisions.

I believe he targeted a lens that would still allow me to read and do other indoor things without glasses, which is how I usually behaved before I got the IOLs. The Vivity at -1D seems to achieve that very well.

I used to be a tech writer; I should be more clear!

That makes sense. I was wondering how the surgeon could end up at -1.0 D when targeting -2.0 to -3.0.

The 3 feet I quoted is a very rough estimate based on closing the other eye. The thing is, binocular vision helps so much, even at distances where one eye is a bit blurry. So take my measurements with a grain of salt. And a different optometrist six months ago gave the prescription for that eye as +0.25D. Different day, different doc, different mood, who knows? But maybe there's some truth to that measurement and that eye is more pushed toward distance than I thought. For my mini monovision setup, it doesn't really matter.

Vision with 2 eyes at -0.25D would probably be better than that. But two eyes won't likely end up exactly the same anyway, due to physical differences.

"Actually that amount of cylinder (astigmatism) is not that large and should be easily handled by almost any toric lens, including the Vivity."

I had a -1.5D cylinder in my glasses, Pentacam measured my corneal astigmatism at 2.5D. In another clinic, I was offered to remove it with LASIK. This would probably give better clarity than a toric lens, but if I am preparing it for near vision, then maximum clarity is not necessary. But there will be fewer holes in the eye and possible complications.

For distant vision, all hope is in the right eye, there the astigmatism is less and before it was always better than the left.

It is unfortunate that predicted astigmatism rises with the removal of the natural lens. Currently what is in the lens must be offsetting what is in the cornea to some degree. Not common, but I gather it does happen. Some thoughts on addressing the issue:

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1. I would presume that the Pentacam number is based on the corneal plane. If so, that is not a perfect fit for the Vivity toric. The maximum cylinder power available is 3.0 D at the IOL plane which converts to 2.06 at the corneal plane. That leaves correction a little short of ideal.
2. You should ask if the predicted residual cylinder was measured another way, such as with an IOLMaster 700. In my case the surgeon had two estimates of residual cylinder, which were not the same. I recall him saying his experience is the actual is usually somewhere between the two. I presume those were from the IOLMaster and the Pentacam.
3. My experience is that with a residual cylinder of -0.75 D my near vision is negatively impacted. I see a drop shadow on letters, and in particular when they are white letters on a black background. In my distance eye I have a similar amount of astigmatism but I see no impact from it.
4. The Tecnis and Clareon lenses come with 3.75 D cylinder option which converts to 2.58 D. That would be a small over correction. Most surgeons prefer to under correct cylinder rather than over correct, thus flipping the axis. I see that the B+L enVista Toric is available with a 3.5 D cylinder option which converts to 2.45 D at the cornea, or a very slight under correction. It may be your best choice for a toric if both methods of measuring your predicted cylinder come out to be 2.5 D at the corneal plane. I think the enVista is a good lens for a near eye in mini-monovision as it has a neutral asphericity which extends the depth of focus to the range claimed by the Eyhance. It will not do as much as the Vivity but will do more than an aspheric monofocal.
5. The normal method of calculating IOL power uses spherical equivalent not just sphere. The cylinder component adds to near vision and without it near vision is compromised some from what is targeted. I say that because a good strategy would be to use a toric, and if it does not achieve the results you want then the cylinder can be reduced with topography guided Lasik. To do that you want the sphere alone to have enough myopia to maintain good reading. If that is the plan you should ask to target sphere alone and not target based on spherical equivalent. My exploration of using Lasik on my near eye to reduce cylinder ran into a dead end. My sphere alone is not enough to give me good near vision without the astigmatism. My target was set based on a spherical equivalent.

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   I hope that helps some. My thoughts would be to use a toric, and if you can find a surgeon that does the B+L then the enVista likely would be a good choice.

“You should ask if the predicted residual cylinder was measured another way, such as with an IOLMaster 700. In my case the surgeon had two estimates of residual cylinder, which were not the same. I recall him saying his experience is the actual is usually somewhere between the two. I presume those were from the IOLMaster and the Pentacam.”

It turns out that in addition to Pentacam and IOLMaster, there is also Verion from Alcon.

Today I was in another clinic and took new measurements, none of them match the others.

So will count now on the online calculators the lenses for all possible options.

Happy are those who didn’t bother and put what the doctor chose for them, but I already got into this topic, I’ll have to dig deeper.

"the cylinder can be reduced with topography guided Lasik. To do that you want the sphere alone to have enough myopia to maintain good reading. If that is the plan you should ask to target sphere alone and not target based on spherical equivalent."

And this is a very important remark, which must be noted for all.

Today's doctor somehow sluggishly reacted to the question about Lasik, but, probably, it is necessary to leave reserves of myopia even more than astigmatism itself, because it is not even, it can be seen on the Pentacam map.

Irregular astigmatism which I have in one eye, seems to impact vision, including near vision more than the symmetrical astigmatism I have in the other eye, even though the measured amounts are about the same.

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Based on the two Lasik clinics I visited irregular astigmatism can be effectively minimized with topography guided Lasik, providing the cornea is thick enough to tolerate the Lasik. Mine was not. The surgeon also thought I may have Keratoconus. My Optometrist does not think so, but the surgeon says while others might risk Lasik on my eye, that he will not. And, as I mentioned you have to leave enough myopia to have effective reading vision after Lasik significantly reduces the astigmatism. This should all be carefully planned out before jumping into a toric lens. For example you will want to find out if your cornea can take Lasik, and also how much sphere the Lasik surgeon would like to start with.

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If I had it all to do over again with what I know now, I would have asked for a toric IOL with a 1.0 Cylinder power (AcrySof IO effectively about 0.7 D at corneal plane), and with a sphere power 0.5 D higher than the one I got, to leave me with about 0.38 D more myopia. I'm pretty sure that would give me significantly better reading vision without any Lasik.

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I think if your toric IOL selection is well planned you probably don't need Lasik. You do have to be sure of your required cylinder power though. The IOLMaster 700 measures it, as does the Pentacam. I am not sure about the Lenstar 900.

you already answered your question. since the right eye is essentially useless as you say, its putting all the work on the left eye, which is why it is tired likely. all that would seem to be a non issue with mini mono. just my 3 cents

ron, why did you not get a toric on the near eye?

with two multifocals, do you suffer from any glares, halos,starbursts?

thx much

forget it. you already answered

im confused still. why would one target sphere and not spherical equivalent?

It is a bit of a long story, but there may be some lessons in it, so I will relate it as briefly as I can.

My surgeon recommended an AcrySof IQ Toric with 1.0 D cylinder, and said it would be a good match for my predicted 0.75 D astigmatism. I then reminded him that when I had my initial screening for my first eye 18 months prior he said that this eye had irregular astigmatism and it might not be suitable for correction with a toric lens. He was quite taken aback by that information, and said that he had to do further checking and that there was no point in having any further discussion at that appointment. He said he would have to call me back after he reviewed the information.

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He was in the middle of transitioning his practice from what he previously had in a public hospital to a private clinic that since my first eye was done, he had set up. I concluded that my prior data from an IOLMaster 700 and Pentacam were not available to him in the private clinic. At the new clinic he was not able to display the topographic image that he showed me at the public hospital 18 months earlier. That is what one needs to see to determine if the astigmatism is a regular bow tie or hourglass shape or an irregular shape.

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In any case he called me back the next day and admitted that the astigmatism was irregular and he was unsure if a toric would benefit me or not. We discussed it some, and he said that if I went non toric I could have the remaining astigmatism corrected with Lasik. Cost was not an issue for me, and I decided that would be the safe way to go, and decided on the non toric. He hit the target for -1.50 spherical equivalent including the astigmatism.

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After surgery I found I had good reading vision but there was a drop shadow on letters, that made it less than perfect. The cause was identified to be the irregular astigmatism, and I got a referral to a couple of Laser clinics. The first one I went to told me that they could fix the astigmatism but I would lose my reading vision as they could not increase the sphere myopia to replace what I was getting from astigmatism. That was not an acceptable solution. Went to the second clinic and they basically told me the same thing, and also diagnosed what the suspected might be the cause of my astigmatism - keratoconus. With that condition they said my Lasik results would not be predictable and said they were not willing to attempt any kind of correction.

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In the process of all this an optometrist at the second clinic gave me a phoropter test. After fully correcting the vision for this eye which included 0.75 D for astigmatism, she showed me what the vision was with and without the astigmatism correction. It was like night and day. With astigmatism correction the letters lost the drop shadow and were amazingly sharp. I realized at this point that I made a bad decision in not opting for the toric lens. It would have done the same thing.

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With Lasik not being a fix, that left doing a lens exchange to a toric as the only reasonable option. The surgeon at one point offered to do that, but I turned it down. I did not want to subject my eye to that intervention, and decided I just needed to accept what I got.

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I think the ironic part of all of this is that if I had not questioned the surgeon on the need for a toric, I would have gotten one, and had a much more successful surgery. The hard lesson I learned was that sometimes one can overthink things. I think I did in this case, and paid the price.

Standard practice with all the IOL power calculations I have seen is to use spherical equivalent. However, depending on what output one is looking at the results may be displayed at SE or as sphere and cylinder. At the end of the day SE determines what you see though.

are you saying if you have irregular astigmatism, a toric can still work?

Yes, while I do not have a toric lens to prove it, I believe the phoropter test in my case shows that a cylinder correction is better than nothing. I don't know if that would be the same for everyone.

Words to live by 😃