Another gap in my knowledge

I am curious, Ron, what if someone had 20/30 vision but excellent intermediate and near vision.

Would that be a acceptable compromise if someone prioritized intermediate and near vision?

Thanks Lynda. Does that mean that aiming for 5% more myopia would considerably increase my intermediate and near vision? I think I heard something like that before but I don't know how that would work. I guess it's the same principle as aiming for -2.0D versus -1.75D... ?

Going from a distance eye vision of -0.25 D to -0.50 is a very small step but in the wrong direction for good distance vision. Similarly it is a very small step towards slightly better intermediate vision, and will do almost nothing for near vision.

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If one has a priority on near/intermediate vision, mini-monovision is a much better solution as you have one eye at -1.50 D. That is actually going to give good near and intermediate vision. -0.5 D is not.

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What one would gain by targeting one eye to -0.5 D is that you could go as far as -2.0 D in the other eye, and that really would step up near vision. The price paid would be a loss in distance vision and potentially the need for prescription glasses for good distance vision.

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I think a much better strategy is to target -0.25 D for the first eye, and if that is achieved then target -1.5 D to -1.75 D in the second eye. That will give good near vision, good distance vision, and still respect the maximum differential of 1.5 D.

While you present good points, I would like to end up at -0.25 in my far eye. Here is the deal: so much of the world that I look at is out beyond 3 meters (10 ft). That is not just for driving.

The defocus curve will largely be due to your eye characteristics. At least in my case, the ablity to see fairly close with my far eye, which achieved about -0.25. For driving, seeing the dashboard instruments is often cited as important, those are pretty darned big. You don't need 20/40 vision to see the dashboard instruments.

IMO, the best reason to target -0.5 is that I may only be able to hit within 0.5 of my target. It would irritate me to end up on the wrong side of zero.

This is not to say that targeting -1.0 or even -2.0 is wrong. If you are a gunsmith rather than a shooter, you might like to be glasses-free while doing close work. And having both eyes focused close will improved depth perception. The reality is that there is very little depth perception due to binocular vision at 10 ft. Binocular depth perception is a closer-in thing.

So my target will be -0.25 (done) and tentatively -1.75. But that is not what I think would be best for everybody. There are many right choices.

The only caution I would say with your explanation is that the terms intermediate and near are not very well defined, other than intermediate is further away than near. The defocus curve is just that - a curve. By offsetting a monofocal you can't boost both intermediate and near. To do that you need a bifocal or trifocal lens like the PanOptix. All you do is move the curve over a very small amount. So, there will be a much bigger impact on the "distant intermediate" and extremely less on the "near near".

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With proper mini-monovision the intermediate range is very well covered by the near set eye at -1.5 D. With one eye set at -1.5 D and the other at -0.5 D, the brain is going to pretty much ignore the -0.5 D eye at near distances. I guess what I am saying is that with mini-monovision at -0.25 and -01.5 D there is no significant value in compromising the distance eye by going down to -0.5 D. All you are doing is compromising distance with no real value gain in the intermediate range.

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This all said my distance eye after surgery was Sphere -0.0 D, Cylinder -0.50 D, for a spherical equivalent of -0.25 D, exactly as planned. On my last eye exam my Cylinder came in at -0.75 D, with sphere remaining at 0.0. So the SE has inched up a bit to 0.375 D. The higher astigmatism in this eye is probably one of the reasons I can see a computer monitor down to about 1.5 feet with this eye only. Astigmatism is kind of a poor man's EDOF. However if I had the choice I would get rid of the astigmatism, and not intentionally leave larger amounts of it. The exception may be the situation in another thread here with two parents in the UK. They charge a ridiculous amount of money for a toric lens. In that case I would sure be tempted to leave a small to moderate amount of astigmatism, as long as it is properly included in the SE target.

While I agree generally with everything @jimluck says, I want to underscore what I take to be the key point: "You have to think about what is important to you".

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Some people, not me, so prioritize very good vision from far to near that they're willing to risk, or even accept, the possibility of negative optical phenomena that comes with multifocal IOLs.

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Some people, me included, are willing to accept the much, much smaller risks associated with mini-monovision, especially knowing that if they're unlucky problems can be cured by wearing prescription glasses.

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In choosing mini-monovision, some people prioritize very good near and intermediate vision over distance vision. Others prioritize distance vision. After research, self-reflection, and discussion with my surgeon, I chose to prioritize near/intermediate. At the same time, my desire to at least have a good chance at legal driving vision--20/40--informed both my choice of targets and of IOL (Eyhance). In the event, I lucked out. I enjoy 20/25 distance vision and J1 (= 20/22, usually rounded to 20/20) near vision and, of course, very good intermediate vision.

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The key point is that only you can decide what's important to you and how much money your willing to spend and how much risk you're willing to take on to try to get there.

I agree. Some get hung up on the "fact" that an IOL targeted to plano has a more limited diopter range covered than one targeted for nearer. However in the real world we see in distances of feet and inches, not diopters. So while you chop of half the defocus curve by targeting plano that is simply the cost of being able to see well in the distance. The part that is beyond plano is beyond infinity, and of no value. In the real world the distance from 3 feet to the moon is much larger than from 8" to 3 feet. I would suggest this is a technical quirk and should have no influence on the decision to target nearer or not. The real issue is accuracy and not going positive. A small positive error is not the end of the world. My brother ended up at +0.25 D sphere and -0.50 D Cylinder which on a SE basis is 0.0 D or plano. His vision is good and can see the dashboard well. The Hill RBF formula predicted that he should have gone one step higher in power and would have avoided this, but he was not convinced. The outcome is still pretty much the same. It likely cost him a little bit of near vision.

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That brings up another point. Some focus on the sphere only. Almost everyone has some astigmatism, and it is negative and makes the SE more negative. If you forget about the cylinder then your SE outcome is going to be more negative than you expect. It is something that should not be overlooked when trying to target an outcome to highest possible precision.

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Given the uncertainly I think one should always target a slot, not a number. If your actual outcome for the distance eye is -0.25 D SE, then a reasonable target for the near eye is -1.5 D to -1.75 D SE. Always ask to see the IOL Calculation sheet so you can make the final decision as it will almost never be a quarter diopter even number.

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Some surgeons who promote the Eyhance seem to be the ones also pushing the target of -0.50 D in the near eye. They talk about a flat point in the defocus curve that I cannot see, and that one should go further negative to take advantage of it (even though it is not there). I think more that it is to increase their odds that they get some intermediate vision that the Eyhance promises, but is very questionable in outcome.

Regarding the meaning of "intermediate" and "near" vision, articles containing defocus curves state the defocus levels (= distances) at which visual acuities were measured. In my reading, intermediate generally is considered to range from 60-80 cm. Because -1.25 D = 80 cm and -1.50 D = 66 cm, those are the most common defocus levels used when articles talk about intermediate vision. For near vision, I generally see 40 cm (-2.50 D) used for near vision, although the Jaeger chart uses 14" (35.6 cm).

Thanks RebDovid! Very well said and much appreciated!