How to get good vision from reading distance to about 6 feet (or beyond)?

RonAK My prescription for the eye that has had surgery is +1.0 sphere and -1.0 cylinder. I am trying to figure out what this says about the vision in that eye. Does your answer above apply here such that my eye is now overly farsighted damaging both near and far vision? If so do you have any idea what to read to learn more about this?

Freddi, how do you see out of that eye without glasses for reading and distance? Do you know what your measured acuity (e.g. 20/NN) is for that eye? How does your your surgeon explain why you got +1.00 and -1.00?

Ron, thanks for your comment. The option to replace my right eye IOL is not feasable, I had YAG 3 months after the implant, so the capsule is compromised. Plus, the IOL has been in too long now, and the risk of capsule damage and retina detachment during extraction is too great for my comfort. So, the best I can do at this point is to tune the upcoming IOL in my left eye for the most optimum monovision. I've tried monovision with glasses, and I'm comfortable with it.

So, what's the best IOL and target SPH for my left eye for 1-6 ft range, any ideas anyone? I'd like to be better informed this time prior to a consult with the new surgeon. The last time I thought I could rely on the good judgement of my experienced surgeon for my right eye, and I ended up with sub-optimal results, despite his 20+ years of experience, his use of the Femtosecond laser and ORA technology; I paid close to $2,000 extra out of pocket for laser/ORA for poor quality results...

Have a look at this article:

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

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In particular look at Figure 2 which shows the defocus curve for the Eyhance in orange colour. Without going down the rabbit hole too far the vertical scale is visual acuity. 0 is 20/20, -.1 is 20/15, and +0.2 is 20/32, or good but not perfect vision.

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The horizontal axis is in diopters, but it can be converted to distance. 0.0 is infinity or long distance. -0.5 is about 6 feet, and -1.0 one meter or about 3 feet. You divide 1 meter by the diopter value to get distance. -3.0 is about 1 foot.

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As you can see from the graph and comparison of the Eyhance to the monofocal, the Eyhance does not drop as fast as you get closer. That is what you are paying for when you buy it. It extends the distance you can see 20/32 (0.22 LogMar) out from 3 feet to 2 feet or about 0.5 D.

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BUT, when you say your prescription requires a +0.5 D, that suggests the surgeon missed on the power required to get your peak vision at 0.0 D. Instead it is at +0.5 D on the left, and the whole orange curve shifts to the left by 0.5 D. That means you lost the closer vision you were supposed to get with the Eyhance. And to a lesser degree you distance vision at 0.0 D is reduced too. That is why you have compromised distance and closer vision.

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The normal practice is to target -0.25 D or slightly to the right of the 0.0 position, or leave you slightly myopic, instead of far sighted. This reduces you distance vision by a very small amount, and actually increases your near vision, as the whole curve is shifted 0.25 D to the right.

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Defocus curves are a bit hard to understand, but I hope that helps.

If you look at the defocus curve you can select the offset you want to get maximum vision in the 1 foot to 6 foot range. For example if you pick -1.5 D that is about 2 feet optimum, and about what I have. I can see quite well from 1 foot out to 6 feet, and even the TV at 8-10 feet is watchable at that distance. I have a monofocal. If you use the Eyhance you will get a little closer vision and you may want to offset it by a little less in the -1.0 to -1.25 range. You have to target a window as you now know that they do not have total control of where you end up.

Thanks Ron, I'll invest a bit of time to learn how to interpret these.

My first surgeon never discussed with me any of the relevant facts, so I was clueless about precision, LRI not being an exact science, etc.

Hopefully my next surgeon will actually talk to me, and deliver better results.

As a side note, I've read that several teams (one in Utah, one in Boston I think) are testing the use of laser (Femtosecond?) to either re-shape the already implanted IOL to improve refractive errors, or change the implanted IOL's hydrophilic or hydrophobic property to add toricity or change it's refractive characteristics. That would be much better than the use of lasers to mess with our aging corneas... Hope it becomes available soon for us to benefit from it...

If you want to be more precise print out a copy of that defocus curve and shift it right by a couple of different amounts. Then look along the 0.2 LogMAR horizontal line to see where it intersects with the shifted curve. That will determine your near and farther limits of good vision.

I don't have eyehance. I have J and J toric monofocal so there is no close vision to lose. I dont really think my distance vision is compromised except for the astigmatism that remains. this is my right eye.

I still have not had surgery on the left eye which has very useful near vision but distance vision that is poor, even with progressives. Both eyes together have very very good distance vision and I can get by for a while longer with the near vision in the left eye. My doc has proposed -1.5 for the left eye with the same lense type as the right. I worry that this minimonovision will be hard to adjust to. I get dizzy sometimes now when using eye hand coordination and I think it is due to the big difference in the vision between both eyes and the fact that this is a monovision of sorts. So I know my doc's goal was 0. But ended up at +1for my prescription.

Sorry, but I mixed my response to you in with the Eyhance lens that Allen has. You could look at the same Figure 2 from that article though. It also has the J&J Monofocal on it. Your vision in that eye would be a spherical equivalent (SE) of +0.5 D which is not that bad. SE is your sphere plus 50% of the cylinder. But, from experience the contribution you get from the astigmatism part is a little suspect. But, to your question going to +1.0 does hurt your distance and near vision. It is not a good place to end up.

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What is your prescription for the non operated eye?

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I think a -1.5 target in the second eye is a good choice if you were closer to 0.0 in the operated eye. Ignoring the cylinder if you go with a -1.5 that will give a total differential of -2.5 D which is a bit much. What you might want to do is try different power contacts in the non operated eye and see what you can tolerate and still get some closer vision.

" if you go with a -1.5 that will give a total differential of -2.5 D which is a bit much."

Not sure I understand.

1. If I go with -1.5, how did you get a diff of -2.5D?
2. And what's the nature of the -2.5 diff being a bit much?

Thx,

Allen

Anisometropia is the total difference between the two eyes. 2.5 is the difference between +1.0 in one eye and -1.5 in the other eye. In a perfect mini monovision world you would target -0.25 in the distance eye and -1.5 in the close eye. Your anisometropia would be 1.25. It is the difference between the two eyes that can cause you to have reduced binocular 3D vision and distance judgement issues.

Ron, I think I'm understanding the defocus curve now. But... if 0D on the horizontal axis is infinity and it gets closer if you go right of 0D, what happens when you go LEFT of 0D? What distance is +0.5D? How can you be farther than infinity?

Also, did you say you have residual astigmatism after your surgery? Did you have a toric IOL or LRI? Why do you have some residual astigmatism?

Good question. on being left of 0.0. When you are there, you are far sighted. Some people mistakenly think they have some kind of super distance vision in the distance when they are far sighted. They do not. The distance equivalent of 0.0 D is infinity. If the eye is focusing on point beyond that, it is a distance that does not exist. They are simply off focus and pay for it with reduced visual acuity. And of course being far signed compromises the close vision too, as you can see from the defocus curve. It is a no man's land where you do not want to end up, and why most surgeons target to be -0.25 myopic. This said I have seen some surgeons who advocate targeting 0.0 or even a bit + with the Eyhance lens. Their reason is that the defocus curve is quite flat, and if you go positive the loss in distance vision should not be that high. But it is significant at the close end, and you lose near vision. They are just sacrificing your close vision to be in the ballpark with distant vision. Not a good practice in my amateur opinion.

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My near eye turned out badly. I should have gone with a toric, but since I have irregular astigmatism I could not get a straight answer from the surgeon as to whether or not it would work. He said that I could get any residual astigmatism fixed with Lasik after, so I went with a non toric lens. Then I found out I was not suitable for Lasik, and he missed a bit on sphere which left me at -1.0 to 1.25 rather than -1.5. He said that was ok as my astigmatism would make up for it. I suspect it does to some degree, but perhaps because it is irregular not so much. I have a bit of a drop shadow on letter, especially when they are white letters on a black background. It looks like I am going to have to live with it. Hard to be really upset when in decent light I can see down to about 1 foot. I retrospect I should have gone with a toric. I may not have reduced astigmatism a lot, but it probably would have been better. An optometrist at the Lasik clinic did an eye test on my left eye and showed my what an astigmatism correction does compared to none. It was amazing. I could clearly see 20/15 with it, and had a hard time with 20/20 without the correction. I should have known better as I had tried a toric contact prior to surgery and noted that vision impoved with it. It just didn't click. The surgeon offered to explant the lens and put in a toric. Perhaps I should have taken up the offer, but it is kind of too late now, considering the complications of an explant.

In unoperated eye sphere is -3.0 and cylinder -2.25. That eye has good close vision but not so good distance vision, though the eye sees well with the progressive lens in glasses.

If you want to simulate monovision with contacts I would suggest starting with a -1.5 D sphere and -2.25 toric contact lens. That should leave you close to -1.5 D myopic and reasonably good reading vision. The question is how well will you tolerate that with +1.0 in the other eye. You may want to try different sphere powers in the contact that are + and - 0.25 D from that power to see how well they work overall for reading and with your other eye.