Target vs actual refractive outcomes?

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I've been doing some research on target vs actual refractive outcomes after cataract surgery.  It seems that most outcomes are within 1 (either plus or minus) of the target and around 50% are within 0.5 of the target.

What I can't find is whether most were plus 1 or 0.5 or minus 1 or 0.5 from the target.

So for example, if your surgeon was aiming for refractive outcome of -2.00 and you ended up with -1.50 then it was plus 0.5 from target and if you ended up with -2.50 then you were minus 0.5 from target.

I want to find out if more people are coming out plus target or minus target but I can't find that information.

I have to make a decision about my second eye (which I've finally decided after much agonising and changing of my mind to have slightly myopic so that I can have blended mini monovision for close and intermediate). 

Not sure what my right eye has come out at yet as it's only a week since I had it done - my surgeon aimed for near vision which is exactly what I have but I don't know what he actually aimed for in dioptres or what I actually have.  I will ask at my check up tomorrow.

I'm just curious to know if people ended up with plus or minus what the target was as that may give me some indication of what I may end up with in my second eye if there's a clear bias one way or the other.

I'm trying to figure out if I ask my surgeon to try for -0.75 am I likely to end up at -0.50 or -1.00?

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12 Replies

  • Posted

    CaroZim,

    Your inquiry is within the realm of any eye MDs expertise. Target refraction is an exercise they do everyday as it has to do with personalizing their A constants (which in reality is never a constant) given a particular intraocular lens and their preferred surgical technique. With the advent of optical biometers and new IOL calculation formulas it is safe to say that 98% will be within +/- 1.00D, and 80-82% within +/-0.25D. The only outlying numbers will come from the very long and very short  eyes, 

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  • Posted

    I asked a fairly similar question recently.  I also wonder is targeting say -2.00D and getting -1.50D is a minus or plus error as it depends on how its considered, but I was told that is a -0.50D error.  The charts I've seen on line show more minus than plus errors which presumably is a deliberate bias as you would otherwise expect it to be roughly even.

    In my case I was mildly myopic in the eye I've so far had surgery on (-1.25D, -0.50D astig) and now after surgery with a -1.39D target I am either -0.75D or -1.00D both with -0.5D astigmatism. The difference is which optometrist does the measurements (my regular one or the eye hospital) as they are always 0.25D different on both eyes.  So I could be 0.40D to 0.65D out :-)

    Targets are always a gamble though so for my first I picked one I was comfortable with at least +/- 0.25D although sadly it missed by more than that.   I am also aiming for a mini mono-vision near/intermediate result, ideally -1.25D and -1.75D but with the first at -0.75D to -1.00D and targets of -2.00D or -1.65D for the second its a lottery as to which to pick.

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    • Posted

      Funny that they consider it a minus error when in fact it's actually a negative number moving closer to zero which I would consider a + increase (basic school maths taught me that!).  Anyway, I still don't know which way is more common when comparing targets with actual (closer to zero (plano) or further away from zero (plano)).

      My right eye was done for close up and my Dr told me he aimed for around -2.00 - 2.50 and according to the test I had today I'm somewhere between -2.25 to 2.50.  He reckons it will improve over time to about -2.00 as I had collagen cross linking 3 months ago and he expects my eye shape to change slightly.  All to complicated for me!

      Left eye will be done this Friday 9th Feb and I asked for it to be slightly myopic so that I have a monovision that enables me to see reasonably well intermediate and a bit blurred in the distance. So I guess that's around -0.5 or 0.75. Hopefully I'll only have to wear glasses for driving or movies and will be glasses free for everything else.

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  • Posted

    My left eye was done 2 years ago densed cataract used laser monofocal 23, and it is cristal clear for far distance and  clear for middle ground and i used glass for reading.

    Right eye was done a month ago with laser densed cataract and i asked for distance and the doctor agreed and the iol card says 25. I had no eye issues and my eye pressure was good.

    Now i can only read, with that eye and every thing else are blurry with the right eye. 

    And i aimed for distance and the doctor agreed with that plane.

    I strictly said and emailed the surgary manager "no mono-vision" for me before the cataract sugary.

    I am afraid i have monovision now. As you said + and and - may have played the role, but not this far i think.

    The Doc says this lense for far distance. I dont know Where else  to find what lense was used in my eye.

    The doctor says glass free is a boon! And it is a better condition than before the surgary! 

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  • Posted

    I believe most eye surgeons try to get within 0.50D of the target, also try to get residual astigmastism cylinder to 0.50D or less.

    My right eye took over a month to stabilize, but it made it very close to the target which was -.025D, its close to 0D now and 0.50D or less residual astigmatism with a Tecnics toric monofocal IOL in my right eye.

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    • Posted

      Thanks  Night Hawk - I also have a Tecnis toric monofocal in my right eye (and will have the same put in my left eye this Friday 9th Feb).  Right eye is currently around -2.25-2.50 and he expects it to improve to around -2.00 or so due to the collagen cross linking I had done in October last year which may lead to a slight change in my eye shape and improvement in my vision.

      Do you have anything in your left eye yet? 

      I'm hoping to be slightly myopic in my left eye so that I end up with excellent close, good intermediate and okay distance vision.  I don't mind being a bit short-sighted as I nearly always wear sunglasses when I'm outside and if I'm driving at night I'll have a pair of standard distance glasses for that. 

      Whatever I end up with I'm sure I'll be much better off than my current -5.50 with -1.00 astigmatism situation in both eyes!  If I can be even 80% glasses free I'll be better off than my current 100% glasses dependent situation.

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    • Posted

      My left eye has only a very early stage cataract that doesn't affect its vision yet, probably will take years more for that eye to need surgery.  Since it can correct with eyeglasses to exceptional vision 20/15 or better I don't want to risk it until needed for that eye.  Its got about -2D cylinder astigmastism and a little myopia -0.50D so its able to correct with eyeglasses and essentially a clear lens for the right eye with the toric IOL corrrecting that eye.

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  • Posted

    Hi I was -5.0 and -4.25 pre surgery.  Now need +.5 and +.75 correction.  Off to PRK soon for fix.
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    • Posted

      Does that mean that you ended up at -0.50D and -0.75D and are having the PRK correction to take you to plano (0D) in both eyes?

      So basically your eyes ended up more myopic than the target.

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  • Posted

    CarolZim...No I was overcorrected and now I need a +.75 and +.5 for being farsighted.  Believe me not a good way to be.  So I went from using -4.25/_5.0 glasses to now the Plus side as Dr overcorrected vision.

    So yes I plan to get some kind of Lasik/PRK/Epi-Lasik/Lasek done to get to plano on distance.  I will still need readers. 

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    • Posted

      Steve, before you’ve had your surgery done did you and your Dr talk about multifocal intraocular lenses. If so you might try yourself first with a multifocal contact lens and see for yourself if this fits your visual requirements or not. ‘Cause if you like your vision with the CLs then you may benefit from a piggyback multifocal intraocular lens. 

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