Tecnis Symfony - downsides other than possible night time rings?

[nplm]

I've been considering monofocal IOLs set at about -1.5D which is similar to natural lens to give a useful range when not wearing glasses/contacts or the Symfony IOL targetting -0.5D which will still need readers up close.

I've already received useful information here but the one point I still am searching for are what are the downsides during the day when the often mentioned rings around lights aren't a factor.  

Symfony provides a single elongated focal point rather than two or three points of focus with multifocal IOLs but surely this must reduce overall quality compared to a monofocal's shorter but more accurate focal point?    I've seen the charts and pictures on the Tecnis site showing impressive results compared to monofocals for contrast but there must be some downside even minor given the focal point pictures?

My goal is to have really the sharp vision in the close and intermediate ranges no matter whether achieved with glasses or contacts over IOLs hence why multi-focals aren't on my shortlist as I think even low adds may be too compromised based on my experience with multi-focal contacts.

[JohnHaganMD]

There are a lot of posts here about the Symfony most notably "Software Developer"  Since he is happy with those they are very effusive. If I were having surgery I would not have a mutifocal or any "premium" IOL put in only a monofocal or a monofocal toric. To many "dysphotopsias" with any type of "premium" IOL including the Tecnis.

[nplm]

Thanks for the input.

If I go monofocals set similar to my current -1.5D myopia am I correct in assuming that the defocus over intermediate and distance is similar to my natural lenses?

I appreciate there will be no near accommodation but as I already have a +2D reading add I've not got much left anyway.

I find this mild myopia a reasonable compromise as I can still function without correction such as first thing in the morning but I wouldn't want to have much worse vision at the other ranges than with my current myopia.

[JohnHaganMD]

Please read this article carefully and several times it contains the information important to you.  If you still have questions please post:  http://www.medhelp.org/user_journals/show/1648102/Consider-ALL-the-Options-Before-Your-Cataract-Surgery-Working-Through-Whats-Best-For-You

[nplm]

I have read your excellent article several times before.

However it doesn't confirm whether a natural lens with say -1.5D would give better results from intermediate to distance compared with an IOL set the same (closer would obviously be dependent on accommodation left in natural lens).  Distance would be a bit blurry for both but would it be to the same?

I assumed they would be the same but I've read a couple of comments where people said it wasn't the case and haven't been able to get any information from them as they're not posting at present.

[JohnHaganMD]

No they are not the same. The natural lens of the eye can variable focus (called accommodating). It weakens as we get older, called Presbyopia, and catches up with most people in early to mid forties. Even though middle aged and older people need reading glasses, bifocals, trifocals or multifocals the lens can still generally focus some giving a clearer depth of focus.  A monofocal IOL has a distinct focal point that is clear. It can be figured mathmatically to the 1/100 of a meter. That is not much use in humans.  A IOL that leaves a person -1.50 dioter refractive error will be focused about 26 inches from the eye. How big of a range is clear cannot be scientifically determined because it varies from person to person depending on a number of factors that cannot be measured such as pupil size and mobility, length of eye and radius of curviture of cornea, presence of astigmatism.  But the short answer is the human lens will have a greater range of focus than a monofocal IOL.

[JohnHaganMD]

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[nplm]

Thanks.

I had presumed that my +2D reading add which is still slowly increasing meant I don't had much accommodation left and hence a fixed monofocal wouldn't be much worse.

What is the average minimum accommodation a natural lens has with age?

[JohnHaganMD]

No wrong presumption and that's why reading glasses start at +0.75 and go to +3.25 or +3.50 (age 80+)  Averages are not very good. If you want to push the point you can go on the internet and read about over the counter reading glasses and the average ages they "fit"  To read at 1/3 meter requires 3 diopters of focus. If you subtract the power of the reading glass from 3 that is how much roughly the eye is providing at 1/3 meter (roughly 13 inches)