What do these numbers mean

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Hi l am having vivity in both eyes, my surgeon said he is setting the non dominant eye for 20.5 and the dominant eye for 19.5 . Can someone please explain what these numbers mean and will that give me good distance vision in both eyes.

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11 Replies

  • Edited

    Those are the powers he has chosen and those numbers alone don't tell you anything. What you need to know is what the predicted refraction is for those powers.

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    Typically though surgeons will choose what is called "first minus". So if the predicted result from using a 20.0 power IOL is +0.11 and the predicted result from using a 20.5 power IOL is -0.23 most surgeons will choose the minus 23 even though plus 11 is closer to zero (a refractive result of zero is 20/20 aka plano). That is because it's always better to end up slightly near-sighted than slightly far-sighted since most of day to day life happens within the 2 to 10 foot range… not infinity. So being slightly (very slightly) near sighted is more "functional" for anyone other than an airline pilot.

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    Anyway you need to ask your surgeon what the predicted refractions are.

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    Also i see your surgeon specifically mentioned eye dominance so I might infer from that that your surgeon is planning to do 0.5D of mini-monovision. This is a very common approach with Vivity. The idea is to make your "near vision" eye slightly more near-sighted to ensure usable near vision (i.e. for using your phone). So the distance vision in that eye won't be quite as good but when combined with the other eye you might still achieve 20/20 or 20/25 distance due to binocular summation (both eyes working together)

    • Edited

      Thanks, yes my surgeon said he is doing the non dominant eye first at -0.5 and the dominant eye second and he said he is going to set the dominant eye to give me the best distance vision, my main aim is to have good distance vision in both eye without glasses, but of course the more near vision l can get will be good

    • Edited

      I'd say you have a good plan. Half a diopter is such a small amount that it won't hurt your distance vision much at all, especially when combined with the other eye that will be set for the best possible distance. And I think having glasses-free "iPhone" vision is such a huge lifestyle benefit that it's worth the VERY slight compromise in distance vision.

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      The only thing I MIGHT say is, I might do the distance eye first. If you get a better than expected result in that eye (since results can vary from person to person, the IOL is only one variable) you might not have to do the 0.5D offset. But I imagine different surgeons have different opinions on which eye to do first and why. Just a thought.

  • Edited

    These are the powers of the lenses he is planning to use. About all you can determine from them is that you must be slightly far sighted.

    • Edited

      does far sighted mean near vision seems blurry. l dont think l am far sighted as l dont need glasses for anything either far or near. Is it possible to be slightly far sighted and not realise it? if the right eye is 20.5 and the left 19.5 which one is far sighted? Is there a chance the surgeon could have got those numbers wrong or is it done by a computer that doesnt make mistakes. If his made a mistake with the calculations does that mean l might need glasses for distance

    • Edited

      In rough terms a 19 D lens is what would be used with someone that is plano. However, that varies depending on the dimensions of the eye. If you have an average sized eye the right eye is perhaps about a +0.75 D, and the left a +0.25 D. The right eye could be slightly more far sighted. But these are small corrections and something that you may not be aware of unless you get your eyes tested for eyeglasses.

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      This is no indication that anything is wrong. It is normal for both eyes to not be exactly the same. If the surgeon has done the calculations right and the surgery goes well, I am sure you will have good distance vision if that is what he targets to get. It is all about the target.

    • Posted

      thankyou, you said if he gets the calculations right?, if the calculations are off target , does that mean l can still have good distance vision but l will need to wear glasses or contacts to correct the vision

    • Edited

      The calculations are all done by computer and are usually pretty accurate especially if you've never had LASIK before (which can throw them off) and if you have a pretty average axial length (about 24mm). Typically these measurements are done with a machine like the IOL Master 700. Safe to assume you had such a scan performed.

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      And yes, glasses are always an option to do slight corrections after surgery to fully dial you in. But ideally your result will be so good that you don't feel the need for glasses. The whole point of Vivity is to give you a wider range of usable vision so you don't need glasses as much after surgery. But yes, glasses are always an option.

    • Posted

      so the eye thats 20.5 is more farslighted then the eye thats 19.5. is that correct, l think l noticed with the 20.5 eye its harder to read stuff with that eye, l guess that makes sense

    • Edited

      John, we all take a risk that the surgeon will have good measurement, will select the right formula, and make the right decision to use the correct lens. The best you can do is make your wishes known to the surgeon that you want the best distance vision.

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