Is It Wise to Get Monofocal Focus Points Set Differently on Each Eye?

How about close up? You said l0 inches to infinity.

At closer than say 8-10" vision goes downhill very rapidly. I can barely read my watch if I move it to 4-5".

Did you have good close up before the implants? (8 to l0 inches)?

I was myopic in the -2.0 range before cataracts, and 10-15 years ago I was more in the -3.0 to -3.5 range. So yes, when you are myopic you get quite good close vision. The issue is that when you get your eyes corrected to see distance you can't see close. That is why people end up with progressive glasses as they get older.

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But, as far as cataract surgery goes, it does not matter so much where you are starting from. It is much more about where you want to end up.

Because of this post I have written my ophthalmologist indicating that this might also work for me. Sounds like what I am looking for and you have had such good results. One issue is my moderate dry AMD....The Opthamologist seemed to push for intermediate as a selection since with AMD one might someday use visual aids and distance would not be the right monofocal choice for some reason? I haven't researched that one yet. Anyway thanks again. Your post was extremely helpful and informative!

I am not a doctor by any means and I have not suffered from AMD. I have only had cataract surgery using monofocal lenses in a mini-monovision configuration. What I read about AMD is that you should avoid multi focal IOLs, and EDOF IOLs as they reduce contrast sensitivity which is reduced with AMD as well. That would mean avoiding lenses such as Vivity, PanOptix, Symfony, Synergy, and Eyhance. The lenses which maintain the highest contrast sensitivity would be monofocals like the Tecnis 1 and the Alcon Clareon. And the thing to remember about these monofocal lenses is that they deliver the highest contrast sensitivity at the same distance as they deliver the highest visual acuity. If your lens is set for distance then the highest contrast sensitivity will be at distance, and if set for close then the contrast sensitivity will be close also. This however is correctable with eyeglasses. So I am not sure why one would pick close contrast sensitivity over distant contrast sensitivity.

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You asked about the conversion of defocus diopters to distance. You simply divide 1 meter by the diopter. If your lens is set to give you maximum vision at 0.0 (plano) then the distance is infinity. At -1.0 D the distance is 1 meter or about 3 feet. At -2.0 the distance is 1/2 meter or about 19". -3.0 is 1/3 meter or about a foot.

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So I am not sure why the surgeon would recommend a close distance for the IOL. Perhaps there is more to the AMD issue than I know about. My thoughts would be that if one had one eye set for closer maximum contrast sensitivity and the other set for more distant contrast sensitivity then all bases would be covered...

That certainly appeals to me also but will be talking with my doctor next Tuesday to see what she says. Thanks again!

Just got an interesting post from Lynda111 who had technis 1 put in both eyes with an intermediate focus and has great distance, intermediate and close up vision now. If intermediate is only 20 to 40 inches I am surprised? Have you heard anything about intermediates?

All I can say is that we have to manage our expectations based on the published defocus curves for the lenses. They are based on visual acuity tests of, hopefully, a large number of subjects, not just one person. When you see these curves they sometimes have an error bar with each data point which gives an indication of the variability between subjects. They can be quite wide, which suggests the outcomes with a specific lens can be different from person to person. But, as I say we need to manage our expectations based on the average, not specific individual results. If you look at Figure 2 in the article below you will see the blue defocus curve for the Tecnis 1 lens. As shown it is in the normal set for distance mode. LogMAR peaks at 0.0 at 0.0 D which is far distance. A LogMAR of 0.0 is 20/20 vision. A LogMAR of 0.2 is considered the limit of reasonably good vision, and is about 20/32. If you look off to the right the blue curve hits the LogMAR of 0.2 at -1.0 D which is about 3 feet. Now if you target the lens for "Intermediate" which is not a very precise way of describing it, but lets say that it is at -1.0 D, or 1 meter, or 3 feet. The whole curve slides over to peak at 3 feet. You will get 20/20 vision at that distance. However, at the full distance or 0.0 D position the vision will have dropped to a LogMAR of 0.2 or 20/32. In the other direction the curve slides over so that the 0.2 LogMAR is now at -2.0, or half a meter or 18" or so. So, based on the average defocus curve if you set the lens at -1.0 D and are happy with 20/32 for distance, and close vision of 20/32 at 18" then it is an option.

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Now notice the error bars on the blue curve. If you are one of the very lucky ones vision could be much better near and far, although one cannot be sure that those who got better than average far vision will also get better than average near vision. And, on the other hand if you look at the bottoms of the error bars, the unlucky ones, vision could be much worse. In short it is a case of YMMV (your mileage may vary!).

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Review of Ophthalmology PUBLISHED 15 APRIL 2021 IOL Review: 2021 Newcomers

Interesting Analysis. Would you say your choice was less risky

although it requires a trial with contact lenses first.

Note that the Review of Ophthalmology article takes its Eyhance/Tecnis1 data from "Comparison of an aspheric monofocal intraocular lens with the new generation monofocal lens using defocus curve", Yangzes S, Kamble N, Grewal S, et al., Indian J Ophthalmol 2020;68:12:3025-9, which is available on-line.

In preparing to speak with my ophthalmologist, I searched for multiple such defocus curves. Others that are available on-line either freely or (potentially) through your library, include:

"Clinical evaluation of a new monofocal IOL with enhanced intermediate function in patients with cataract", Gerd U. Auffarth, MD, PhD, FEBO, Matthias Gerl, MD, Linda Tsai, MPH, D. Priya Janakiraman, OD, FAAO, Beth Jackson, PhD, Aixa Alarcon, PhD, H. Burkhard Dick, MD, PhD, FEBOS-CR, Quantum Study Group, Journal of Cataract & Refractive Surgery 47(2):p 184-191, February 2021

"Optical Assessment and Expected Visual Quality of Four Extended Range of Vision Intraocular Lenses", Juan Antonio Azor, MSc; Fidel Vega, PhD; Jesus Armengol, PhD; Maria S. Millan, PhD, Journal of Refractive Surgery, Vol. 38, No. 11, 2022

"A comparison of clinical outcomes and optical performance between monofocal and new monofocal with enhanced intermediate function intraocular lenses: a case-control study", Jungah Huh1,2, Youngsub Eom, Seul Ki Yang, Young Choi, Hyo Myung Kim and Jong Suk Song, BMC Ophthalmol, 2021 Oct 16;21(1):365

"Visual Acuity, Wavefront Aberrations, and Defocus Curves With an Enhanced Monofocal and a Monofocal Intraocular Lens: A Prospective,

Randomized Study", Mayank A. Nanavaty, MBBS, DO, PhD; Zahra Ashena, MD; Sean Gallagher, BMedSci; Steven Borkum, DipOptom (SA); Paul Frattaroli, MA (Hons), MA (Post-Grad); Emma Barbon, BSc, Journal of Refractive Surgery, Vol. 38, No. 1, 2022

I'm sure that there are more freely available for other IOLs. By the time I began searching for multiple defocus curves for the same IOL, however, I'd already narrowed my choice to a 'pure' monofocal, such as the Tecnis1 and Clareon, and the extended range of vision, but still classified as a monofocal, Eyhance, all subject to switching one or both eyes to a toric IOL, depending on residual astigmatism calculations.

That is a hard question to answer. I have been myopic all my life and first started using soft contacts about 50 years ago. They worked fine until I started to lose my near vision due to age induce presbyopia. I tried contact monovision briefly and was not adverse to it, but I got tired of the contact lens hassle and switched to progressive glasses exclusively. When it came time to deal with my first cataract which was one eye only my surgeon suggested full distance correction with a monofocal, and to think about monovision for the second eye. I did that, and with the issues one can have with one eye having an IOL correction and the other corrected with eyeglasses (the image size from each eye can be different) I settled on using a contact in my unoperated eye virtually full time. I found better contacts, and liked the monovision thing a lot. I simulated -1.25 and -1.50 and about -2.0 (no contact at all) in the unoperated eye. -2.0 was not good, but the other two were fine. So by the time it came for my second eye which really did not need surgery for a year or so, I was well prepared for monovison. I did not see it as a risky choice at all.

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I think the choice kind of comes down to what you want to see without glasses on. As long as you select a monofocal IOL it really does not matter where they are set, as eyeglasses can correct if they are set for distance, intermediate, close, or one eye close and the other far. I look at it as a plan A and plan B. Plan A is what you hope to get without glasses, and Plan B is what you get with glasses on. And, you can choose either of those plans on a daily or hourly basis. I wanted to see very well for both distance and close without glasses so the mini-monovision made sense to me, with the back up plan of progressive eyeglasses. Things turned out well and using the backup plan is almost never needed for me. So, I guess what I am saying is that for me it was a very low risk approach, but it may not be for everyone.

OK. Got it! I am sure my doctor will have her own ideas also! One thing I am grateful for is your opinion about waiting 6 weeks. I am sure I am going to wait at least a month now as I can't see rushing this since it is new for me and I have not had much experience with surgery or eye issues....... (never even wear glasses) and haven't noticed much change even with the cataracts and AMD (you adjust without knowing it). Thanks again for the detailed information....it really helps as I had no real knowledge about this until I found this site!

One thing you have to watch with defocus curves is whether they are based on monocular testing or binocular (both eyes). The curves should always be a bit better when both eyes are used. In that IOL Newcomers article the Alcon lenses are binocular and the J&J ones are monocular, so they are not directly comparable.

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I have had issues finding accurate defocus curves that make sense for the Eyhance lens in particular. Those curves in the Newcomers article are misleading for the Eyhance. It shows that peak visual acuity is the same for the Tecnis 1 as for the Eyhance. That cannot be true as the Eyhance smears the focus point by varying the power of the lens from the centre to the periphery to get some EDOF. It is a zero sum game, in that when you move the light to a closer distance you lose acuity at distance. The Alcon Vivity and AcrySoft curves are more representative of what really happens.

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The graph that I find most honest and interesting is the one provided by Bausch and Lomb on their B+L enVista lens. It uses neutral aberration correction as compared to full correction by the Tecnis 1, and nearly full correction by the AcrySof IQ lens. They show in this graph how it is a zero sum tradeoff of visual acuity vs depth of focus. If you have access to the enVista I think it is an interesting monofocal lens alternative. My brother got it in Manitoba as the basic healthcare free option. He has tested 20/15 in the eye that was done. So, if there is a compromise to visual acuity it is not evident in all cases. This lens is also said to be more tolerant to a less than perfect eye, and lens positioning in the eye, whereas the Tecnis 1 would be least tolerant.

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I think the question I would ask the surgeon is why she thinks there is more benefit to having maximum contrast sensitivity at an intermediate distance than to have it at distance or near, or one eye at near and the other for distance. Seems to me that having one near and the other far blends the value of contrast sensitivity across the range of distances.

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If your surgeon advises intermediate, I would go with that recommendation, particularly since she/he knows you have AMD. Their may be a reason why she wants you to have binocular vision. I don't have AMD but as I just said in my other post, intermediate worked well for me.

Do you know of a good explanation of monofocals and diopters etc. This is all a new vocabulary to me since I haven't gone through this before. Thanks.

I don't know of a good link that does a basic explanation. The basic formula to convert diopters to distance is to divide 1 meter by the diopter.