Distance vision

Thanks RebDovid! I understand everyone is different, but could you share the numbers for your left and right eye? For example, -1.75D?

What I'm really trying to learn is how much difference there was between your eyes. Also, did you have experience with mini-monovision using contacts?

Would you say that distance vision works well for reading when supplemented by readers or progressives? I'm not familiar with Shamir Computer or Workspace lenses.

Using spherical equivalents, that is, adding together the spherical correction and 1/2 the predicted residual astigmatism, we targeted -2.0 D for my near eye and -1.0 D for my distance eye. Due to refractive surprise, I ended up at -1.5 D and -0.5 D. ( I put the near eye first because that's was the first eye operated on. Prioritizing near and intermediate vision, we wanted two bites at the apple.)

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Yes, I trialed mini-monovision with contact lenses both before surgery on my first eye and during the interval between the surgeries, which were six weeks apart. I'm sufficiently risk averse that I wanted cataract surgery to target a smaller amount of mini-monovision than I successfully trialed with contact lenses.

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I'm not sure I understand your last question. When I read, my near eye is doing most of the work and I don't wear any glasses. My wife uses readers, which take away her distance vision. She doesn't need more, but the annoyance factor in having to put them on and take them off is leading her to deciding between the Shamir lenses.

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You can find out about the Shamir Computer and Workspace lenses by searching Shamir Lens USA, then look for the appropriate drop down menu. Basically, the lenses are like progressives, and Shamir is a leader in the field of progressive lens design, in that they provide a no-line, continuous flow from intermediate to near vision. According to Shamir, they work from 15" and out. The Computer is supposed to work to about 5'; the Workspace, with a narrower field of vision, to about 10'. The Workspace also provides a smidge of distance vision at the top. Pre-cataract surgery, I used the Workspace lenses for working at my desk. The distance vision was so good that I occasionally forgot I wasn't wearing my everyday progressives and would find myself driving with them. In conversation with a few opticians and my wife's ophthalmologist, who also uses the Workspace, I found my experience isn't unusual.

I'd been wondering if those with IOLs set to mini-monovision need any form of glasses, which I see is yes. That said, it sounds like your wife with IOLs set for distance and without mini-monovision finds the need for readers more onerous than you do with mini-monovision and one eye set for distance. I hope I've got that straight!

Are the Shamir Computer and Workspace lenses similar to progressives without optician or optometrist involvement or do you need a prescription?

Do you have a sense of what caused the refractive surprise?

What do you mean by two bites from the same eye?

Perhaps I haven't been clear. I don't need glasses for intermediate and near vision. Nor do I need them for driving, at least in good daylight or night time driving conditions. I'm nevertheless getting single vision glasses in a mini-monovision configuration targeted for distance and intermediate to have just in case I feel the need for glasses in less favorable driving conditions or when driving in unfamiliar areas.

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The Shamir Computer and Workspace lenses are prescription lenses. As I understand it, Shamir's software uses the patient's progressive prescription to calculate the appropriate prescription for its lenses, also taking into account various measurements that the optician is supposed to do to improve the final result. If you're interested, I strongly suggest reading the Shamir webpages for the lenses and reading their on-line handout.

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I really don't have any idea what caused the refractive surprise. I only know from all that I've read that ending up 0.5 D from the target is considered a reasonable result. And in my case it worked out very well indeed.

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By two bites at the apple I mean that starting with the intended near eye gave us two chances to nail near vision. Even if the surgeon hit the target, it's possible that I would have been unlucky and not gotten the near vision I wanted. After all, defocus curves report mean averages; someone has to end up with worse vision than the average. Had I not gotten the desired near vision with the first eye, I at least would have had the chance to decide whether to target even greater myopia for the second eye. Bear in mind that by prioritizing near and intermediate vision I already was accepting the likelihood of needing glasses to drive and watch TV; I just lucked out in terms of ending up with 20/25 distance vision (20/20 in my distance eye).

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This reasoning is why people who want mini-monovision and prioritize distance generally start with the distance eye. If the result from the first eye isn't good enough, they either can try again, and give up on mini-monovision beyond whatever turns out to be the difference between the two eyes, or settle for whatever distance vision the first eye provides and see how much intermediate/near vision they can get from the second eye.

When you say you can read fine without glasses, do you mean you can read a book for several hours comfortably? I ask because the reports I've see here that mention it usually say they have usable reading vision but to read a book like that they still use readers.

As to computer glasses, I have had them for several years now (haven't had cataract surgery and need to stop procrastinating and get it done). I use them pretty much all day for everything and even walk the dogs outside with them day and night and see well enough to do that without problems. The only time I switch to my distance contacts is for driving. Admittedly I'm not one who cares about seeing the leaves on trees individually.

Thanks RebDovid! Great to know about 2 bites from the apple.

I apologize for not seeing your post sooner.

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Yes, I can read a book, or my iPAD, or my computer monitor, comfortably for several hours. Having been rather myopic and worn glasses as far back as I can remember, not needing glasses is something like a miracle.

Yes, of course. With a distance set monofocal vision improves from the OK 20/32 point at 2-3 feet progressively to 20/20 or perhaps even 20/15 at full distance. That is unless there are other vision issues like uncorrected astigmatism.

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But keep in mind the same happens with mini-monovision in the distance set eye. You may not get 20/15 as you might with both eyes set to distance, but 20/20 is realistic, providing you target -0.25 D for the distance eye.

Thanks Ron! Could you clarify if those with mini-monovision need glasses? I've heard yes and no on this...

The objective of mini-monovision is to be eyeglasses free. However, there will almost always be some uncorrected error. Glasses can make that final fine tuning adjustment if you want it. I have prescription progressives but almost never wear them. About the only time would be when driving in the country in the dark. In the city day and night I am eyeglasses free. I do reach for my mild +1.25 D readers occasionally when reading very small text on paper in dimmer light. That said I can read restaurant menus in typical restaurant dim light without glasses. I would not bring glasses if I am going to be dining out.

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Some target more myopia than standard mini-monovision calls for and they will most likely be stuck with glasses for distance. Not sure why they do that, as I would much rather be slightly dependent on some cheap readers than on prescription glasses.

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I didn't even fill my last eyeglasses prescription as the glasses I have are close enough, and I never use them anyway.

Judith

I will let Ron comment , but

remember that no two eyes are the same. How well you will see after surgery varies from person to person. Ron said he was "blessed" and Rebdovid said he " lucked out." I was blessed myself, targeting binocular intermediate vision I ended up seldom needing eyeglasses.

Thanks Ron! That brings to mind the suggestion by my surgeon regarding whether to pursue mini-monovision without a having a trial with contact lenses. The plan would be to have my LE corrected to -1.75D (which was the initial plan for both eyes) and then see how I like it after 6 weeks or so. However, if I do the contact lens trial on the RE after surgery to the LE and decide that mini-monovision is not for me, I'll miss the opportunity to have both eyes set for distance and will be limited to both eyes set for -1.75D which I wouldn't want. Does that make sense?

Yes, something those considering cataract surgery should definitely keep in mind! That said, how do I overcome my uncertainly and make an informed choice when I can't rely on the experience of others to guide my path?

Mini-monovision can't guarantee that you'll have very good vision across all three fields: distance, intermediate, and near. The best you can do--ideally with the assistance of a sympathetic, open-minded, knowledgeable surgeon and defocus curve information about the mean average visual acuities a particular IOL produces--is to maximize your chances of getting the results you want. That's why it's important to think carefully about whether distance/intermediate or near/intermediate is more important to you. After all, it doesn't matter what most people choose. What matters is what you want.

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In my case, reading, especially @Bookwoman, self-reflection, and talking with my surgeon led to my eventual targets. And my surgeon was fully on-board.

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If indeed having excellent distance vision is your top priority, I would not begin by targeting your first eye to -1.75 D or to any other seriously myopic target. Rather, depending on your IOL calculations, I would discuss with your surgeon whether to target the first or second minus refraction. Assuming you get desirable distance vision, you and your surgeon then can decide how much more myopic to target your second eye.

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Assuming illustratively that your first eye is at -0.25 D, if you've successfully trialed a 1.75 D difference with contact lenses (both before and after the first surgery), then you reasonably could target -1.50 D or even -1.75 D for your second eye. While that can't guarantee excellent near vision--and your chances are better with Eyhance than alternatives such as Clareon or Tecnis 1--it should lock in excellent intermediate vision and give you anything from functional to excellent near vision. (I'm taking J1 near vision, which is what I measured last Friday, as being excellent.)

If you would not be happy with both eyes set to -1.75, then I would do the distance eye first and target -0.25 D. Then try contacts in the other eye to see how much myopia you like, and go for it if you like it, and if you do not, then target -0.25 D in your other eye too.

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Also it is quite possible with careful selection of targets to see all distances with mini-monovision. I would be quite sure if you ended up at -1.75 in the near eye, and -0.25 D in the distance eye, you would see all distances down to about 8-10', and out to the moon very well. Mini-monovision does not need to be as complicated as some make it out to be. Those outcomes would also honour the maximum recommended differential between eyes of 1.5 D.

Thanks RebDovid! I only anticipate a trial after surgery for LE when a contact could be used on the RE as a trial.

8.8" is -4.50 D. To project vision at that distance with both eyes targeted at -1.75 D, one would have to look at a defocus curve for the IOL targeted at emmetropia and then (1) eyeball the visual acuity at -0.25 D, (2) move the curve 1.5 D to the right to place the original -0.25 D result over -1.75 D, and then (3) determine the result at the new -4.50 D. If the defocus curve showed binocular visual acuities, however, the result with a 1.5 D difference between the eyes would be at least slightly worse.

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Dr. J. Morgan Micheletti's Alcon advertising supplement in CRST Global contains a binocular distance-corrected defocus curve. Eyeballing the Clareon's BDCA at -0.25 D, it appears that the Clareon's mean average is c. 0.03 LogMAR. And eyeballing the Clareon's BDCA at -3.00 D, which is as far as the curve goes, it appears that the Clareon's mean average there is c. 0.75 LogMAR. If we move the curve 1.50 D to the right to simulate a -1.75 D refractive target, the 0.75 LogMAR that appeared opposite -3.00 D now is the mean average BDCA for -4.50 D.

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0.75 LogMAR is 20/112 Snellen. Accordingly, I find it difficult to believe that refractive results of -0.25 D in one eye and -1.75 D in the other eye reliably would produce very good vision down to 8-10".

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What about 14"? Making life easier for ourselves, let's actually use 14.31", which is -2.75 D. With the distance eye at -1.75 D, the indicated mean visual acuity at -2.75 D formerly appeared opposite -1.25 D. Eyeballing the Micheletti defocus curve at -1.25 D, that would be a mean BDCA of LogMAR 0.25, or 20/35.5. To me, this looks more like functional than very good vision.

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Turning now to the Eyhance, at the time I was deciding on refractive targets I had found and averaged together ten Eyhance defocus curves, both binocular and monocular. At a -1.75 D refraction, the mean average visual acuity was LogMAR 0.103, or Snellen 20/25, and at -1.50 D, the mean average visual acuity was LogMAR 0.147, or Snellen 20/28.

Sorry, but you obviously do not understand the concept of defocus curves, the difference between peak visual acuity, and acceptable visual acuity. If I had cataract surgery done and now needed to get two pairs of prescription glasses to see properly, I would consider that to be a total failure. It is a waste of time to read your posts.

To project vision at that distance with both eyes targeted at -1.75 D, one would have to look at a defocus curve for the IOL targeted at emmetropia

Small point, the zero on the horizontal access is not necessarily emmetropia. Instead it is the best focus point, which may correspond to the "target" if things went as planned.

Zero were emmetropia, then the positive D numbers to the left would be meaningless.

Ultimately, I think you're correct, but I don't think your point changes the fundamental analysis. mistaken in the context of defocus curves. My source is an article by Dr. Jeremy Keval entitled "Understanding the Defocus Curve: It's All About the Optics". According to the article:

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"Defocus curves are created by presenting a series of positive- and negative-powered lenses in front of a patient’s eye and measuring the degree of “defocus” that is induced. The zero reference on the x-axis is controlled across patients by correcting for the best possible distance acuity. Using 0.50-D increments, the defocus curve measures a patient’s binocular visual acuity often from +1.00 D to -4.00 D. In doing so, the resulting acuity that is measured can be used to simulate what the patient’s visual acuity would be at different distances. To understand this concept, we have to remember the most basic formula in optics, the formula for focal length: f = 1/D. For example, when an emmetropic patient views a logMAR chart through a plano lens, the image is at infinity representing distance vision. Place a -2.00 D lens in front of the eyes, and this would essentially equate to viewing the chart at 50 cm (20 inches). When looking through a -4.00 D lens, it would be the visual acuity equivalent at 25 cm (10 inches). Thus, the defocus curve can be created in a more controlled means for evaluating visual acuity at various distances."

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On the one hand, Dr. Kieval supports your point by stating that "[t]he zero reference on the x-axis is controlled across patients by correcting for the best possible distance acuity." On the other hand, he also speaks about "when an emmetropic patient views a logMAR chart through a plano lens, the image is at infinity representing distance vision." This is what I had in mind.

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The point remains that, at least according to the Clareon defocus curve presented by Dr. Micheletti in the Alcon advertising supplement, visual acuity at even 14" is not reasonably describable as "very good".

With Eyhance and mini-monovision, I "need" zero pairs of prescription glasses to see from 20/25 at distance to J1 at near. (By the way, I had understood J1 to equal 20/20 Snellen. From research prompted by your post, I now see that it's more accurately 20/22. According to "Understanding Near Vision Eye Tests" by James W. Hough, Senior Manager, Technical Services, American Society for Nondestructive Testing, "the Snellen number is usally rounded to the nearest 5", which is how 20/22 gets to be reported as 20/20.)

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My wife, with both eyes targeted for distance, only "needs" readers for near vision. She plans on getting Shamir Computer or Workspace prescription glasses because she finds it annoying to put on and remove readers when switching her view from her computer screen to books and papers on her desk. BTW, Hoya and Zeiss make similar, well-regarded prescription lenses.

@RonAKA, if by acceptable visual acuity you mean the minimum level of visual acuity that is considered to be sufficient for everyday activities, then from what I've read that's generally considered to be 20/40, or LogMAR 0.3, or better.

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Using Dr. Micheletti/Alcon's Clareon defocus curve, with one eye at -0.25 D and the other eye at -1.75 D, mean visual acuity at 14" (-2.75 D) appears to be c. 20/35.5, or LogMAR 0.25. As I wrote, "To me, this looks more like functional than very good vision." If for you disagree, chacun à son goût. I will confess, however, that I don't understand how "the difference between peak visual acuity and acceptable visual acuity" affects the analysis.

"I will confess, however, that I don't understand how "the difference between peak visual acuity and acceptable visual acuity" affects the analysis."

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That is quite obvious.

See https://patient.info/forums/discuss/translating-defocus-curves-from-d-to-feet--803594?page=0#3891077

That jimluck > trilemma response is particularly good.

Key to the image is the table with the Target column on the right. The target would correspond to where the high point of the graph focus is. Then the various lines of the table have distances that each vertical line gets translated to.

Just in case I am not alone, perhaps you will do us the courtesy of explaining. Regardless, I'll elaborate on my comment.

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By "peak visual acuity" and "acceptable visual acuity" I understood you to be referring, respectively, to the best possible visual acuity an individual can achieve and the minimum level of visual acuity considered sufficient for everyday activities. If you're using these terms differently, please explain.

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On this basis, I used the Micheletti/Alcon Clareon defocus curve to discover the indicated mean visual acuities at 14" and 8.8", assuming mini-monovision with the near eye at -1.75 D. @RonAKA says: "I would be quite sure if you ended up at -1.75 in the near eye, and -0.25 D in the distance eye, you would see all distances down to about 8-10', and out to the moon very well." Given the context of the discussion, I took the "8" to refer to 8 inches, not 8 feet.

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Looking at the defocus curve, however, one sees that at 8.8" the mean visual acuity is 20/112 Snellen, and at 14.31" the mean visual acuity is 20/35.5. I doubt anyone would say that the former is an acceptable visual acuity; for me, at least, 20/35.5 at best would be acceptable, it is not, for me at least, very good or excellent visual acuity.

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On the merits, what does this analysis get wrong?

Thank you. It's an interesting approach. (I will note that in this context @jimluck does use emmetropia as a synonym for plano and 0.0.)

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What I did was to collect Eyhance defocus curves; enter the data on a spreadsheet; and calculate mean visual activities for different refractions. The first attachment shows my treatment of the defocus curve from one study. The second attachment shows the mean visual acuities for the mini-monovision configuration that I currently have, namely, -0.50 D and -1.50 D.

The second image doesn't seem right. In the second image, the far eye (-0.5D) sees better at all distances than the near (-1.5D) eye.

The first one, I am not sure. Your first four data columns represent distances beyond infinity, so maybe crosshatch them or eliminate them.

How do the two rows, of the first table, that correspond to your eyes correspond to what you observe?

I'm not seeing what you're seeing in the second image. From 0.0 D to -1.00 D the "far" eye sees better. At -1.00 D, for example, it's 20/22 (far) vs. 20/25 (near). At greater distances, the "near" eye takes over. At -1.25 D, for example, it's 20/23 (near) vs. 20/24 (far), and at -2.75 D (13.12"), it's 20/31 (near) vs. 20/49 (far).

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Regarding your last question, I see better than the tabulated results: 20/20 in my far eye (but 20/25 with both eyes), and J1 (=20/22, usually rounded to 20/20) at 14". It may be notable, however, that distance vision in my near eye is worse than the 20/43 indicated in the image. The greater myopia in my near eye well may explain why my binocular distance vision is worse (20/25) than my monocular vision with my far eye (20/20).

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This difference could have several, not necessarily mutually exclusive, explanations. One is that defocus curves present mean results, often with at least some indication of the standard deviation. Some people have to end up with better results than the mean and some with worse. My ending up with better results than the mean, at least for now, is one of the reasons I describe myself as lucky. Another possible reason may be pupil size. Just now, I can't find that measurement, but I recall it being somewhat over 2 mm. That, too, might conduce to a better result. In all events, the necessarily somewhat imprecise nature of the exercise is why I try generally to refer to the data as indicative.

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Finally, I'd appreciate a more detailed explanation why you think the first four columns in the first image are irrelevant. Sometimes, the refractive result ends up in positive territory, and published defocus curves standardly include data to the left of 0.0D. Although I now see that in extracting the first image I inadvertently truncated column A, Row 11 presents transcribed and interpolated data from the defocus curve in the original article. I thought I took on board your point about distances beyond infinity by leaving blank the distance cells under the positive refractive results.

I'm not seeing what you're seeing in the second image. From 0.0 D to -1.00 D the "far" eye sees better. At -1.00 D, for example, it's 20/22 (far) vs. 20/25 (near). At greater distances, the "near" eye takes over. At -1.25 D, for example, it's 20/23 (near) vs. 20/24 (far), and at -2.75 D (13.12"), it's 20/31 (near) vs. 20/49 (far).

In the -1.25D/80cm/31.5" column, the far (-0.5) eye says 20/23, and the near eye says 20/24 -- a tad worse for near. So I cannot agree with that one.

In the -2.75D/36.36/15.75" column, the far (-0.5) eye says 20/28, and the near eye says 20/43 -- a lot worse for near. So I cannot agree with that one either.

First image:

On the first image, the top two rows (spreadsheet boxes 4M..5Q) of spreadsheet 2. Seem to be a legend to explain the colors. Numbers did not seem to totally match, but that does not bother me.

Row 7 I would either gray-out or hide. Thus, I would not refer to the -1.00 D column, but instead I would only refer to that column as 1 meter (39.37:). I think the purpose of rows 8,9 are to represent distance from the observer, agree?

Finally, I'd appreciate a more detailed explanation why you think the first four columns in the first image are irrelevant. Sometimes, the refractive result ends up in positive territory, and published defocus curves standardly include data to the left of 0.0D.

Since I take the top (horizontal) scale as distance, the stuff to the left of the infinity column would be meaningless.

I addressed two of your points, because they stood out to me.