Just one eye for intermediate monovision - monofocal or Eyhance?

thank you for your reply. i think the contact lens trial is valuable and you helped me understand that even though it won't allow me to see intermediate clearly due to the existing cataract, it will help define the degradation of the distance vision.

you do bring up another issue (in #4) that i hadn't fully considered which is to do Plano or slightly undercorrected with dominant eye and later on (possibly years from now) intermediate with other eye. i discounted that for a couple reasons, 1) that my brain has been working with this monovision/dominant eye arrangement my whole life, so switching that could prove problematic in ways i can't anticipate, and 2) i wouldn't be able to achieve my main goal in the near term of having clear intermediate vision without glasses.

when considering the defocus curves, is the functional difference between an undercorrected monofocal IOL vs. undercorrected Eyhance significant in any way? if not, what would be the target of under-correction for the 18-22” distance, -2.0 (D)?

I would add your natural lens adopts (changes shape to focus the light where it is needed), so harder to evaluate an IOL close vision using contacts.

Eyhance only provides the smallest amount of EDOF. The goal of Eyhance is to provide a little bit of EDOF, which have no worse Contrast Sensitivity Loss or Dysphotopsias than a Monofocal. So every inch you gain with Eyhance is a free lunch; if what they claim is shown to be true over time.

I just quickly pulled up the defocus curve, so make sure to double check my numbers. Looks like that 18”-22” range is around -2 D. And Eyhance looks like it will be around 20/40ish vision on average if you set your distance for Plano. So the 2 questions is: 1) Do you need 20/20 distance and is 20/40 OK for your goals.

Again with Eyhance I think best to use micro-monovision to achieve your intermediate vision goals.

thanks for your reply 😃

My goal for the IOL to provide 20/20 clearest vision at 18-22" and am thinking my other eye is currently close to 20/20 for distance so i will be covered there (at least until it deteriorates with age) plus I am ok with wearing glasses for driving (and reading close).

I'm intuiting from you that this doesn't qualify as "micro-monovision" as it requires more than -1.5 (D)? i have seen terms like mini-monovision and full-monovision but i don't know what qualifies as each, or which category my current natural vision falls into, which is what i'd like to replicate. (my eyes are 1.25 sphere apart)

Do you know what your eyeglass prescription is for your right eye? Or, better still what it was before the cataract became significant? I find it cumbersome to think in distance, rather than diopters. For what it is worth I have about -1.25 D in my near eye. I can see quite well with it down to 12" or so.

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In terms, micro monovision is -1.0 D or less myopia. Mini-monovision is in the range of -1.25 to -1.5 D. Full monovision start at about -2.0 D. If you want to be glasses free for close and distance, I would choose the mini-monovision.

The right eye has been in the -0.75 to -1.50 range for around 10 years. (that's for a distance glasses prescription).

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In my case i'd be in the mini-monovision with 1.25 difference with perhaps an additional -0.25 undercorrection needed to achieve the target with a monofocal IOL. I have read a few times that this might be the case. Is that "best practice"?

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Encouraging to hear you are able to get down to 12". That's with a -1.25 D monofocal type IOL?

Based on my experience simulating monovision with contacts and now with IOLs my thoughts are that -1.5 D in the near eye is very close to ideal. The hardest part about monovision is getting the near eye as close as possible. With the distance eye it is normal to target -0.25 D as there is nothing good about going into the plus zone. It hurts both distance and close up. However, if they miss and you are at -0.5 D it is not all that bad. You could still have 20/20 vision. However if they miss by 0.5 D on a close eye that is not good. -1.0 is going to leave you short of close vision and -2.0 is going to be too much. So it is good to have a frank discussion with the surgeon about error. Keep in mind that IOL powers come in steps of 0.5 D so perfection is not possible.

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My close eye is not simple. I have -0.75 D irregular astigmatism that I did not have corrected as a toric lens is not ideal to correct that type of astigmatism. And my sphere is -1.0 by my optometrist, and -1.25 by my surgeon and 1 other optometrist. When you throw in the rule of thumb 50% of the cylinder then I am at about -1.6 D. But, the irregular astigmatism is giving me a drop shadow on letters which makes reading a bit more difficult. With that whole mix I would suggest -1.5 D is ideal and also ideal is no astigmatism. Has your surgeon given you any idea of what residual astigmatism might be?

I didn't know the astigmatism is factored into the target! While my sphere is -1.5 D my cylinder is -.5 D so it sounds like an addition -.25 D should get added to my target.

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My docter didn't discuss residual astigmatism. And I didn't realize it would change at all with a standard IOL implant. Am i misunderstanding what you're asking?

Astigmatism is a consideration. The objective should be to get rid of it if possible. But, the first thing you need to know is the predicted residual astigmatism if a toric lens is not used. The astigmatism cylinder in your eyeglass prescription is the sum of the astigmatism in your lens, and it may be increased or decreased by the cataract, and the astigmatism in your cornea. One of the measurements taken to select an IOL is a topographical map of the cornea. That map will tell the surgeon what the predicted astigmatism will be with the natural lens replaced with an IOL. In most cases it will be less than the astigmatism indicated by your eyeglass prescription. But, the astigmatism in the natural lens can be offsetting astigmatism in the cornea, and in that case removing the lens makes the astigmatism worse. And the incision itself to remove the lens and insert the IOL will cause some astigmatism. So the short answer is that your surgeon needs to do the topographical measurement and let you know what residual astigmatism is predicted. The minimum power toric lens in the Alcon line corrects down to 0.75 D of astigmatism. If your predicted astigmatism is less than that, it is not worth using a toric as it may make things worse instead of better.

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Now if you are just trying to estimate what your total myopia is now with your natural eye, the rule of thumb is to add 50% of the cylinder to the sphere. But I am not so sure about how good that really is. I have -0.75 D of irregular astigmatism in my close eye, and I am not sure it is really helping me read at all. I'm sure it is causing a drop shadow on text which makes it harder to read. I think the 50% rule of thumb is more intended for what contact to get if you have astigmatism and want to use a non toric contact. In your example it would suggest you get a -1.75 D contact to give you the best correction with a non toric contact. But, it will be a compromise of course. My thoughts are for an IOL target is to just shoot for -1.50 sphere and ignore the astigmatism. But you will almost always be between steps on the IOL as they come in 0.5 D increments. So, if there is one choice just below -1.5 D and one just above, it probably would be better to choose the one just below, rather than the one above.

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That is an important discussion to have with your surgeon, and be warned they may be a little guarded or resentful about your asking about it. It sounds like your eye is close to where you want it with no correction so that would mean they would be selecting an IOL somewhere in the range of 19 D. The powers are all positive and range from 5 to 30 D. One step in IOL power of 0.5 D is about equal to 0.35 D at the eyeglass plane. So say for example your surgeon will have a choice of 18.5 D, 19.0 D and 19.5 D. You should ask and be clear what each one is predicted to leave you with for sphere. When they take your eye measurements they select a formula to use and that formula will make those predictions.

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Does that make sense?

Wow! that does clear things up (no pun intended!) i really didn't know there were these additional considerations. I'm sure if these questions were coming from someone with eye/optics experience rather than a layperson doing online research the doctor would be more accommodating.

Thanks for your thoughts. You bring up several interesting ideas for me.

It does seem like a leap of faith to switch from crossed monovision to non-crossed monovision plus a contact lens for the non-surgery eye, since my brain seems to be wired the other way. I guess i could try to simulate this prior to surgery with contact lenses? I wonder how accurately that might reflect the actual result?

I am pretty set against having to deal with EDOF artifacts and low-light contrast issues which is why i've narrowed my focus to the Eyhance or standard monofocal IOL.

In defense of this doctor, I do think he is more qualified in credentials than the other choices covered under my insurance plan. But I think he is not quick to embrace the latest lens technology and Eyhance is relatively new. As such, his lack of experience with Eyhance is steering him toward the solution he knows works best for picky patients. And if the difference between monofocal IOL and Eyhance is really as small as everyone says, then I should stop pushing for Eyhance, right? On the other hand, I can’t find any negative reviews from any Eyhance patients… everyone seems to be very happy with their choice.

For my particular case, it seems Eyhance could provide the slight bit of extra range to give clear vision in the medium-range I’m seeking. That’ s my thinking at the moment. And that’s why this forum is so useful… to have other people weigh in on other approaches, as well as: Am I splitting hairs (between Eyhance and a monofocal) that won’t matter in the end given all the other factors that influence outcomes, or am I legitimately striving for the best possible solution that would make a functional, noticeable, may even important difference?

Yes you could simulate standard monovision with contacts ahead of time, at least to the degree you see with the cataract eye. The issues I attribute (rightly or wrongly) to crossed monovision is that I sometimes have issues with vision at about 20-25 feet. It seems the eyes fight over who is in control. The other is real close up. Sometimes I have to concentrate to get my closer focus but non dominant eye to focus in the 12" range. There is a study which does seem to validate the use of crossed monovision however. Google this:

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Crossed versus conventional pseudophakic monovision: Patient satisfaction, visual function, and spectacle independence

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You may want to consider that natural monovision may be more forgiving than pseudophakic vision. When I did my contact lens simulations I settled on the close eye being -1.25 D, which is about what I got. Now I think -1.50 D is closer to being ideal with IOLs, and I may even get Lasik to get there.

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You may be splitting hairs on the monofocal vs Eyhance. Some even claim the Eyhance is a monofocal. The difference is more when considering Vivity. Vivity does suffer from contrast sensitivity loss, and that can be minimized by putting it in only the close eye, with a monofocal in the other.

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I was close to getting a Vivity in my close eye but in the end between myself and the surgeon we decided against it.

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One thing to be aware of is that some surgeons are committed to one supplier, typically J&J (Tecnis, Eyhance) or Alcon (AcrySof IQ, Clareon, Vivity). I would caution against forcing a surgeon to implant a lens they are not familiar with. There is an experience factor in working with each lens type.

That is reassuring to read the study you mentioned. The idea of switching to non-crossed monovision never came up in the discussions with the doctor (and if i give him the benefit of the doubt maybe that study is the reason why). And i agree with you about having the doctor work with the lens type they are familiar with. When i asked specifically which monofocal lens brand he would be using he said it depends on the supply at the time. Not what i wanted to hear. Is that a showstopper?

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In your original reply you recommended going with a monofocal in the dominant eye, but why not consider starting with Eyhance, perhaps undercorrected a bit and possibly get more of the intermediate range i'm after in the first place?

With my first eye I was given the choice of a Tecnis monofocal and a AcrySof IQ. The surgeon who seems to have a Alcon bias recommended the AcrySof IQ and I chose it. It has a blue light filter that gives a more natural colour balance than the Tecnis which is clear. There is also a slight difference in the asphericity correction. The knock on the AcrySof lenses is that in the past they have suffered from tiny voids called glistenings. My surgeon said he has seen it but not to the point of it causing any impact on vision. And Alcon claims the issue has been resolved with better quality control in the newer AcrySof material. I hope he is right as I have one in my right eye. Since my first eye was done, Alcon has come out in a newer material called Clareon. That was what I got in my second eye, and is the one I would recommend since you are so young. It is very resistant to glistenings. It also has a sharper edge contour and is more resistant to PCO than the Tecnis or AcrySof lenses. PCO is a significant issue with IOLs and there are some studies which show the Alcon lenses to be more resistant than the slightly different material used in the Tecnis and Eyhance lenses.

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It varies from person to person, but I can see down to 18" with my first eye set for distance. My sphere correction is plano at 0.00 D. With my -1.25 D eye I can see from 12" out to a few feet. My 4K HD TV is about 6 feet away and while it is perfect with my distance eye, it is very good with my close eye as well. Vison is good in the overlapping range between the eyes. I would not target the distance eye to get intermediate vision. You will likely get it anyway, and you would compromise your distance vision. With what I have, I can test 20/20+ with my distance eye, and a bit better with both eyes.

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My thoughts on the Eyhance is that it provides so little EDOF that in a monovision situation it does not seem to add much if anything, and you take the chance on some optical effects. Some say they are great, and others not so much. There is no free lunch, and when you stretch the focal point there are impacts to the vision. Google "aspherical vs spherical iols" and look at the images. You will see many examples of what a spherical lens does compared to an aspherical lens. Despite what the manufacturers claim the EDOF lens smear the focus point just like a spherical lens. You really cannot have an aspheric EDOF, but I believe both J&J and Alcon play some word games by saying the one surface of the lens is aspheric, but it is misleading as the other surface is not, or they would not have any EDOF.

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They are not used where I am, but there are still spherical lenses around. If you go with a monofocal you want it to be aspherical. The AcrySof IQ is aspherical, and the Clareon is as well. Not sure how the Tecnis distinguished between the two types, but they probably have both too.

thank you. so helpful!

Wasn't one of the drawbacks of going to Aspherical Lens that even though it gave better vision at a particular distance, it lost the EDOF of a Spherical Lens?

Maybe the Eyhance "Eye Trickery" EDOF is so small most people don't notice the vision quality difference.

I have not followed the Eyhance clinical trials, except the one that they got FDA approved on, but hopefully there will be some big trials comparing the Eyhance vision quality to a monofocal. Of course someone has to fund these trials and maybe their is no desire to fund such a trial by the manufacturer.

IMHO Emperical evidence seems to show Eyhance has less complaints than Vivity, though at the cost of smaller EDOF.

In our province in Canada, Alberta, the basic lens supplied at no cost by our healthcare system is an aspheric lens. It is the default lens you get without asking. I am not sure a spherical lens is available. They are still made but the surgeon may have to jump through some hoops to order one to implant. I recall there was a thread a while back on a guy from New Brunswick concerned about getting a hard lens instead of a soft one. What it turned out to be is that the default lens they supply at no cost is the soft lens but is still the spherical one, and for an extra $80 they use the aspherical one. In that case I recall they just charged the guy the $80 and didn't even explain what the cost was for. A spherical lens may be a "poor man's" EDOF, but I suspect in Canada and the US it is very seldom used as the aspheric lens gives the sharpest vision. From various sources this is how I would approximately place the lenses for EDOF diopters added:

Aspherical - 0.0 D

Spherical - 0.25 D

Eyhance - 0.4 D

Vivity - 0.6 D

I suspect the negative issues are related to the amount of EDOF in the lens.

For what it's worth, this study states Eyhance has "a spherical posterior surface and a modified aspheric anterior surface"

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RonAKA earlier you wrote

My thoughts on the Eyhance is that it provides so little EDOF that in a monovision situation it does not seem to add much if anything, and you take the chance on some optical effects.

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Please help me understand why the Eyhance extended range would be less of a benefit in a monovision situation? Does that mean it's best used in tandem? (And maybe this maybe why my doctor said i would need to do both eyes if doing Eyhance approach?)

The key word in that study and summary of their findings is the word "good". The spend a lot of time saying that intermediate and near vision was better in the Eyhance compared to the aspheric monofocal. And, it certainly will be. But, all they say about distance vision is that it was "good". The laws of physics say that if you spread out or smear the focal point of the light compared to an aspherical lens the crispness of the distance vision will suffer some. The Eyhance is really intended for someone who wants to put the same lens in both eyes, and have it set for full distance vision, but at the same time want some near vision, but do not expect to be without reading glasses. One could debate whether the Alcon Vivity or the Eyhance is best at that need, but they do work.

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The reason I am saying in a monovision situation that they do not add much is that you are intentionally under correcting one eye to leave you myopic. You are shifting the whole defocus curve to the right by 1.5 D if you opt for a -1.5 D under correction. In comparison the Eyhance is typically only giving you a shift of 0.4 D. But, for sure the Eyhance can be under corrected too, but some surgeons seem reluctant to do that. My point is that by making the myopic shift is the major benefit and in that case the EDOF really does not add much. In theory you could shift it 1.1 D and get the same close vision effect, if the surgeon can hit that number. That would mean your distance vision would be compromised slightly less. But the reality is that with monovison your other eye will be fully corrected for distance and that little bit of extra distance vision from the close eye will be insignificant.

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The Eyhance certainly could be used for the near eye, but I would question the value of it. I seriously considered the Vivity for that purpose but chickened out on it. My surgeon even offered to do the PanOptix in my near eye, but I gave a firm "NO" to that idea. It would have in theory been better as it would give full distance vision and very good close vision. But, in the end my thoughts were that if I stick to a monofocal in both eyes I know what I am getting with each eye, and I have full control. And in my case my distance eye was done first and I came out at 0.0 D sphere and had 20/20+ vision with that eye alone. My distance vision was in the bank already, so all I was concerned about was getting good close vision without reading glasses.

yes, you are really understanding my exact issue! and i am so grateful you have taken the time to share all these details. you hit the nail on the head with my thinking that by using the Eyhance instead of standard monofocal IOL "...would mean your distance vision would be compromised slightly less" and that, i thought, would be a significant benefit. But then you hit the nail into the coffin with "...the reality is that with monovison your other eye will be fully corrected for distance and that little bit of extra distance vision from the close eye will be insignificant." This is where i do wonder how one can quantify this type of thing? I'm guessing i'd lose some 3D imaging that i may or may not currently enjoy. It just seems impossible (short of the contact lens experimentation) to get an accurate sense of the experiential difference and if that would be significant to me. I'm still of the mindset that an undercorrected Eyhance provides added range compared to the standard monofocal so why not go there if i'm willing to accept some loss of crispness in the distance range that would overlap with the other eye's abilities anyway? (This really is the crux of my dilemma!)

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My surgeon was of the mindset that the product should be used in both eyes and that by deciding to do my one eye with it now, i'd also be making the choice to do the other eye with Eyhance later. This was contrary to what i was reading on this forum about mix-n-matching products and a topic that was even confirmed earlier in this thread. So it is curious to me that you just echoed pretty much exactly what my surgeon said: " Eyhance is really intended for someone who wants to put the same lens in both eyes, and have it set for full distance vision, but at the same time want some near vision, but do not expect to be without reading glasses." Maybe the mix-n-match idea of different IOL types is possible, but less common than i thought? And is there some reason Eyhance should be used as a pair?

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My doctor was also pushing back on the idea of undercorrecting the Eyhance. You said "...for sure the Eyhance can be under corrected too, but some surgeons seem reluctant to do that." Is that because it's a guessing game as to how to shift it correctly to match the target?

The advantage of using an Eyhance in the near eye would be that you could under correct the eye a little less than a monofocal and your distance vision with the close eye would be a touch better. Your close vision with it should be similar to but perhaps not quite as crisp at the optimum focal point. At -1.25 D for example with the Eyhance the optimum distance for it would be 39.4"/1.25 or about 32". The optimum for a monofocal at -1.5 D would be 26". Useable vision for both would extend down to 16" or so (LogMAR 0.2), providing the surgeon hits the target. And with a monofocal set for distance in the other eye vision should be good down to 2-3 feet. Since vision does not drop off a cliff when looking at objects closer than optimum for the close eye, there will be a significant overlap in good vision with the two eyes combined. I could watch TV at 8' or so with my -1.25 D eye, but clarity improves when I open both eyes. I still think that once you throw in the surgeon error the difference between an Eyhance and monofocal in the close eye, is going to be a real hair splitting difference. The amount less that you could correct an Eyhance is lower than the margin of outcome error. Only about 72% of cataract outcomes are within +/- 0.5 D. Surgeons apply surgeon factors to the lens power calculation for each specific lens and need to do many surgeries to get the experience needed to accurately predict what the outcome would be. The difference seems to be in where each surgeon positions the lens based on their operating style. For that reason I would be really hesitant in forcing a surgeon to implant a lens they are not familiar with.

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You can see some defocus curves for the Eyhance and Vivity in this article. To get a distance you divide 39.4" or 1 meter by the defocus value. A LogMAR of 0.2 is considered the limit of good vision (20/32 if I remember corrrectly). When you under correct a lens by -1.5 D for example the whole defocus curve for that lens shifts to the right by that amount. From that you can see the impact of under correction for each lens. The other thing you can see with these EDOF lenses is that the extend the focus range to the right, but not to the left. When the lens ends up in the positive range due to surgeon error the impact is the same on both monofocal and EDOF lenses. There is no forgiveness to the left. The other thing about these particular versions of the curves is that the Alcon Vivity ones appear to be binocular and as a result vision is higher, while the J&J Eyhance seems to be monocular. And, the other thing to note is the error bars for the Tecnis monofocal. The curves are averages for a number of people, and the error bar shows the range of outcomes. Error bars are only shown for the Tecnis but each of these curves will have similar error bars associated with them. Unfortunately we roll the dice when we get one of these lenses, or as the saying goes YMMV! As an example my monfocal distance eye is good down to 18-24" on a computer monitor, but the defocus curves suggest the average is more like a meter or 3 feet.

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PUBLISHED 15 APRIL 2021 IOL Review: 2021 Newcomers

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As for 3D vision that is more significant at closer distances where you will have overlap of good vision. A golf ball on a tee, or a tennis ball hitting the racket for example should be in really good vision with both eyes, no matter which lens you pick for the close eye.

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In thinking about your situation longer my thoughts are that if you have gone a long time eyeglasses free with about -1.5 D myopia in your right dominant eye, you are likely to be OK with crossed monovision.

The first paragraph of your previous reply is so helpful to me. The way you explained this is exactly what i've been trying to work through. I really appreciate how you articulated the comparison of undercorrecting both types of lenses. Your conclusion that the difference is splitting hairs given the margin of error confirms that i've been attributing too much significance to the Eyhance literature and best-case scenario. This does help me shift my thinking where i had become a bit entrenched.

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I'm still not sure i fully understand the reason you earlier suggested Eyhance should be used as a pair. Is it that 3D vision is improved? So if i had a monofocal for distance only, along with one Eyhance lens undercorrected for closer vision, then there wouldn't be much overlap at the closer distances where you say 3D vision is more significant. Is that the reason?

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It is true that i have gone over 50 years mostly without glasses, except driving at night or fairly recently reading close to intermediate range. I figured i'd do a contact lens trial to try to ascertain if i should stick with crossed monovision or reverse that to standard monovision.

I don't recall suggesting Eyhance should be used as a pair, other than perhaps a comment that it may be an option for those who want the same lens in both eyes, both set for distance, and are wanting to get closer vision that two monofocals set for distance would provide. My thoughts on the Vivity and Eyhance is that they should only be used in the closer vision eye along with a monofocal in the other eye.

"closer vision eye" as in an undercorrection situation? or are you thinking just for the eye that wants to see a bit closer than a standard monofocal set to Plano?

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the earlier thing that got me thinking you meant "Eyhance as a pair only" was this:

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The Eyhance is really intended for someone who wants to put the same lens in both eyes, and have it set for full distance vision, but at the same time want some near vision, but do not expect to be without reading glasses. One could debate whether the Alcon Vivity or the Eyhance is best at that need, but they do work.

Yes, I think the Vivity and Eyhance from the manufacturer are intended to be used as pairs. They of course want to sell you two of them! But my thoughts are that they are better used in a hybrid monovision configuration where only the closer vision eye gets the EDOF lens. That way the monofocal lens in the other eye can offset some of the negative issues associated with the EDOF.

I'm glad to hear this. This is where my thinking ended up also! So it's reassuring to hear someone with your knowledge and experience confirm. It brings me full circle to my post at the beginning of this thread in that having presented this idea to my surgeon, he pushed back on both undercorrecting the Eyhance as well as using it individually with a monovision lens in the other eye. On top that he suggested they should be used a pair. Furthermore, it may not even be a product he can get and given his seeming lack of familiarity with it makes me realize i shouldn't ask him to install it and that another surgeon would be best for that scenario.

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My conundrum at this point is finding the surgeon with that experience as well as one that is "in network" for my health plan (which i supppose could be changed if needed). Or alternately deciding that the difference between Eyhance and a monofocal is splitting hairs given the margin of error and that i'm too focussed on the slight benefit the Eyhance may provide. Certainly the additional clarity and possibly fewer artifacts of a standard monofocal IOL are real benefits I will appreciate.

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RonAKA i want to thank you for all of your thoughtful replies and helping me understand this whole thing better. I'm sure it took considerable time and I just want to let you know how much i appreciate everything you contributed. Also rwbil replied earlier in the discussion and I want to thank you again too!