Cataract surgery resulted in drastic Sphere swing from negative to positive. Can I still get to 20/20 naturally?

Hi folks I am new to the site. Have been doing a lot of reading and watching Jake’s videos so am getting a pretty good understanding how to reverse a negative diopter sphere prescription. My case is a bit different (maybe a lot different) in that I used to have a mild negative sphere (-1.25) and strong negative astigmatism (-4.5) in both eyes but since my cataract surgery I now have +2.5/-4.5/82 in the left and bit better in the right. I currently have about 20/40 sometimes 20/30 vision so have been without glasses. Close up vision is excellent up to about 90 cm or more. Active focusing has been helping improve my close up even more.

So I am trying to understand the physics of my new prescription. When I had a negative sphere prescription (nearsighted) I understood that the focal point was before my retina thus the need for minus glasses. Given that I had been wearing a minus prescription for 50 yrs for both far and close vision I assume my eye had lengthen. Now that I have what looks to be a strong positive sphere (supposedly farsighted) , I assume the surgeon had tried to match my new cataract lens focal length to my already elongated eye length resulting in ok vision but not 20/20. (As an aside when I wear pin hole glasses I have 20/20 maybe even a bit better.) I don’t quite understand what equivalent sphere means but I know mine is +0.25 when I use the formula which is probably why I have reasonable vision. So assume its my high astigmatism that’s holding me back from 20/20.

Given this long winded story, I’m not sure if progressive diopter reductions in my prescription makes sense or if a plastic cataract lens can even be reshaped by the ciliary muscle. Also with a positive small equivalent sphere, does my eye need to elongate a bit more to match the new lens focal length (higher risk of retinal tear) ? Already had one retinal tear after the cataract surgery which ended up be a blessing in disguise as removing the vitreous solved the serious floater problem in my right eye. A recent flood of floaters in my left eye probably means I will have a tear in that eye at some point. I’ve got to say though, the surgery was easy and so was cataract surgery. If anybody is interested in my experience, would be happy to share.

Anyways, as I mentioned I am working without glasses (nice !) no problem but would love to get to 20/20. Sorry if this sounds like asking for specific advice but its just such a weird situation I find myself in with these new eyes !. I may not even be asking the right questions.

Thanks Again


This has sent me down a new rabbit hole. As I am getting to the age when cataracts may become an issue, I thought it might be a good idea to find out something about it. So I found this article,

and as a result of reading it, the first question I would ask you is what kind of IOL the surgeon implanted. It seems there are several kinds. Considering your astigmatism, it could have been a toric lens. There are also accomodative lenses, which I assume would function more like natural lenses.
With your previous low myopia but high astigmatism, it might have been difficult to come up with the most useful IOL, but it would seem to me that this is a fairly good compromise, with good close vision and reasonable distance vision. But this is complete ignorance talking :grinning:
I should imagine good vision habits and AF can do you no harm, but whether this will get you to 20/20 is anyone’s guess.

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Hi Mario,

Well if you have regular astigmatism (strongest meridian and weakest meridian are perpendicular to each other), it means that the 82 degrees (almost vertical) direction is the strongest meridian so you get directional blur on vertical lines (because you can see the horizontal directional blur on the edge of a vertical line).

So it means you need a -4.5 + 2.5 = -2 diopters on the weakest meridian i.e. in the horizontal direction and +2.5 on the vertical meridian.

So, this is only as I as a layman understand it, but with regular astigmatism your lens should provide a smooth transition from one extreme +2.5 D vertically to the other extreme -2 D horizontal direction. I guess this is why the surgeon chose this lens to have a balance in the middle somewhere between the + and - 2?

So in theory at around 40 degrees you should have 0 diopters if I understand this correctly.

The spherical equivalent just means that removing e.g. 0.5 cyl means you reduce the lens power in the weakest meridian’s direction but add 0.25 sph which increases the power in all directions but your eye will still see the same average power over the directions (cos it’s halfway between the nothing added vertical power and the full cylinder power in the horizontal meridian - that’s why the sph equivalent is half the cylinder)

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what this means for you and the EM method is harder to figure out. I guess active focus cannot hurt but I’m not sure if it’s possible to reduce only the cyl power needed in your weakest meridian… I guess that would be your goal.

Thanks Hannie, I will take a look at the article. Yes I thought I was going down a rabbit hole to ! So I forgot to mention that I also have Keratoconus. The surgeon decided to use a standard lens that did not correct for astigmatism (abbot lab product) as he felt I would have gotten other types of distortion with a Toric. I was fully prepared to pay for the best lens on the market ($1150/eye multi-focal toric) but he recommended a virtually free lens (i guess partially subsidized by our health care system). I’m not complaining that’s for sure as I can see vibrant colors again and have been without glasses for almost a year. The color thing was amazing. You don’t realize how much you are missing when cataracts set in. I wish my diet wasn’t so poor growing up. Maybe I could have delayed or even avoided this.

So my goal is to keep up the good vision habits/exercises and probably avoid fooling around with my prescription until I understand the physics and physiology better. I will continue to use pinhole glasses while watching TV as I find that relaxing on my eyes. It probably doesn’t help to improve vision permanently but at least I don’t have to wear a prescription that I now know will make things worse.

Thanks again !


Thanks Lajos. Very informative on how astigmatism works. This is the physics I was looking to try and get into. I think I need to literally map out what you are saying on graph paper to see if I can even attempt to play with my prescription. I can definitely see that just changing sphere (say going to +2.0 from +2.5) could have unintended consequences in other axis if I’m understanding you correctly. As I mentioned to Hannie, I also have Keratoconus so that throws even another twist on things but its winter up here and I’m retired so I have time !

Just a follow up, I have Abbot Technis ZCB00 Acrylic IOL (+14 D power). I can’t tell if its an accomodative type IOL from their website so I assume its not but I will try and contact them to find out for sure. I didn’t know there’s such a thing as accomodative IOL’s so thanks for that link. If the cilary muscle can’t influence the shape of the lens, then I might be stuck on getting to 20/20. Hopefully I can influence the eye shape over time. The good news is that in the bright sunlight, I have great distance vision. I might have to move to the sunny south !


Hi Mario, Just curious about how your state is today? I have just joind in here and have also had a cataract surgery on both eyes with left me with a -2 myopia (was -9.5 and -8.5 before surgery). I now would like to try to bring down my myopia a bit. So I am sooo very interested in hearing how things works for you.

That would be a fascinating experiment! If you decide to try it, keep us posted.

Hello Marigold. I continue to improve. My recent eye exam showed an improvement from 20/40 to 20/25. I contribute a lot of that to active focus when I do close up reading on my phone or computer. I also try and limit that close up reading which I can now that I am retired. Other things that might be helping is my diet (generally keto/carnivore), using pin hole glasses when watching TV (only if they are fatigued ), and just generally trying to stay healthy. I ended up with a positive sphere (positive 2 with significant astigmatism) in both eyes after my surgery so I don’t know if my eye’s focal length will change more easily in the direction they need to than folks with negative sphere. My lenses are not the so called accommodative lenses so my improvements must be due to just focal length changes in my eye (lens to retina distance) and not flexing of the lens itself. I have not worn glasses since my surgery a couple years back. Hope this helps. Thanks

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I am on. And will update if about my progress. :smile: And if there is no improvment I sure will let you know. My differentials are on their way. I have started out with -1.75 cyl -1 in both eyes and it seems to work fine. I am almost at 20/20 with them. thought I could do computerwork without differeantials but that is not workning. Will be so interesting to have them in a few days.


That was one of the reason I was adviced to get what they called reading -myopia. I just have plain lenses, no astigamatims correction in the eye so I need it very much in glasses I have discoverd. Hope your eye sight will continue to improve.