Is a multifocal IOL not truly multifocal?
Posted , 9 users are following.
This is part of an email I received from my cataract surgeon's office pre-surgery. I am trying to decide between monovision and Symfony (actually an extended depth of focus lens I think).-
"No matter what target or lens we choose, there's no perfect solution and glasses are the solution for further fine tuning of vision afterwards. With either monovision or multifocal, there will be some compromise between very near vision and intermediate vision because we realistically have 2 focal points to work with and roughly 3 major zones of vision."
So is he saying it's actually bifocal, not trifocal or multifocal?
0 likes, 48 replies
derek40125 susan44499
Posted
The comment about "2 focal points" is definitely referring to a true multi-focal IOL, not Symfony. However, the remainder of the statement regarding "no perfect solution" and "needing glasses for some tasks" is accurate for all current IOL's despite any sales literature you read to the contrary.
My advice is to take your time, do your own research, understand the tradeoffs among the various IOL options and how each tradeoff would affect your particular "liefstyle." Ask questions of others who've had the surgery (this forum is excellent by the way) and then make an informed decision.
CaroZim susan44499
Posted
I went with monovision - my right eye is set for close up at around -2.25 and my left eye is set for distance at 0. Intermediate is a bit blurred so I have to wear glasses for computer use. I can see distance perfectly and I can see close up well (thankfully it's getting better as I adjust to the monovision). I have Tecnis toric monofocal lenses in both eyes.
If you've never tried monovision, I would advise that you do a contact lens trial for a bit (unless you have a really bad cataract in which case there's probably no point!). Monovision does take some getting used to but once you adjust I think it's a really good compromise (and you won't get the night vision issues with monofocal lenses that you'll get with multi or trifocals or the Tecnis Symphony lens).
If you currently wear glasses for distance but can see fine close up if you take off your glasses then my advice is to make sure you can still see close up after your operation - people who lose this after surgery find it extremely difficult to adjust to not being able to see close up. If you already wear reading glasses but can see fine into the distance then you'd probably be happy to stick with that and continue to wear reading glasses after surgery.
Mini monovision is also an option and a good compromise for those who don't think they can adjust to full monovision (a difference of 2 or more dioptres between your eyes) - there is plenty online about this and also on this site so I won't repeat it.
Do your research and decide which of the three distances you use the most (near, intermediate and far) and then that will give you a better idea of what to ask your surgeon for.
susan44499 CaroZim
Posted
at201 susan44499
Posted
The earlier multifocal lenses (and probably still the more common ones in USA) are bifocal. That is the reason for your surgeon office telling you that "With either monovision or multifocal, there will be some compromise between very near vision and intermediate vision because we realistically have 2 focal points to work with and roughly 3 major zones of vision."
There are some newer multifocal lenses with 3 focal points. I am not sure about their approval or the availability in USA.
Even though I don't like the night vision issues with Symfony, those are not any worse than with Symfony. So, between the two choices only, I would rather have the extended lens capability of the Symfony lens rather than two focal points with a big dropoff in between.
Between getting 2 Symfony lenses, both set for distance, and two monofocal lenses, with one set for distance and one for intermediate, I would choose the two monofocal lenses. You will be needing reading glasses in either of the 2 cases.
If you want to minimize the need for glasses for reading and also to reduce the chances of having night vision issues, I would suggest getting a monofocal lens set for distance in the dominant eye and a Symfony lens set for intermediate distance in the non-dominant eye.
at201
Posted
In the above post, instead of saying that :
"Even though I don't like the night vision issues with Symfony, those are not any worse than with Symfony"
I meant to say:
"Even though I don't like the night vision issues with Symfony, those are not any worse than with multifocal lenses."
Sorry about the error.
susan44499 at201
Posted
I didn’t realize Symfony lenses were anything but multifocal. Or extended depth of focus, whatever that means. But you mention a Symfony set for intermediate distance.
Sue.An susan44499
Posted
Surgeons will say that closer than 18 inches with Symfony you’ll need glasses for fine print. I see well from 11 inches and beyond and don’t wear glasses. However I do have some night vision issues with concentric circles around certain lights - like brake lights and red traffic lights. I knew ahead of the surgery about those and that would be a trade/off I would have to accept for seeing at all distances.
at201 susan44499
Posted
Setting the Symfony lens for intermediate distance means aiming for the best focus at about 32 inches. One should be able to read reasonably well with that, but will need glasses for distance vision.
The above comment is for using a single eye by itself. The vision with the 2 eyes together depends on the vision in each of the eyes.
susan44499 at201
Posted
Sue.An susan44499
Posted
The only thing I don’t like are the concentric circles around lights at night but I decided I preferred to have good daytime vision without glasses.
Wishing you the best.
susan44499 Sue.An
Posted
He likes them alot. The halos are minor and don't bother him.
Another reason I hesitate to get them instead of monovision is because my optometrist said after having monovision contacts for 20 yrs my eyes may have trouble working together . And that if you get a mulifocal and your vision isn't as good as you'd like, they can't do much. But with monovision they can. (I think she meant glasses or contacts).
Sue.An susan44499
Posted
From a little reading I did this evening regarding AMD it would seem the concern is about contrast sensitivity. Multifocals generally produce less contrast than monofocals due to light scattered between 2 focal points however the contrast sensitivity with Symfony is on par with a monofocal. Got that from the cornea specialist/cataract surgeon’s blog on his experience implanting Symfony lenses (google Dr Por Young Ming).
derek40125 susan44499
Posted
Susan:
Sorry to add more options for you to think about, but since you've worn contacts for so long set up for monovision you could continue with this approach setting the IOL for distance and the contact in the other eye at the point you want for your monovision (not sure if you;d be reversing what the eyes have seen for 20 yrs though). You could also try to switch to muti-focal contacts even over the IOL to add another focal point for that eye.
at201 susan44499
Posted
It is possible that even though your husband's surgeon aimed for the best focus at far distance, one of the eyes has the best focus slightly closer.
The main point is that unless we know what the exact prescription for his eyes (and also best corrected vision in each of his eyes) is right now, it is harder to assume that his results will be duplicated in another person targeting for a similar vision.
michael74313 susan44499
Posted
I have to disagree about there being "no perfect solution." The question is, what is the perfect solution (or best choice so to speak) for you? Certainly there's no "perfect vision" with or without an IOL. Anyways, with that said, I think the perfect or best choice has to do with your biology, the skill of your doctor and of course some luck. I have two toric mono focal IOLs that i have had for a year. After the first IOL, I was quite a bit bothered that my near vision appeared to be lost. My doctor suggested we do the second eye with "mini mono vision" and he set it for distance (like the first eye) but -0.5D in just a bit. That allowed my eyes to still work together so that I see well at all distances. Over time as I taught my brain to hold things around 14": away rather than 5" when reading and I found that new "sweet spot" for near, my near vision continued to improve. I can't say that it will be that way for everyone, but it sure worked out well for me. I'm around 20/20 for distance and 20/25 for near - all with a mono focal.
Most can't adapt to full mono vision and I also was worried that over time, I might wind up needing glasses for both distance and near. Also, depth perception is affected and especially in your senior years I've read it can increase risk of slip and falls. However, most can easily adapt to mini mono vision.
Of course there are other issues with multi focals also such as halos and star bursts at night as well as a lack of contrast and sharpness of colors compared with a mono focal from what I've read. I have two mono focal IOLs and have no night vision issues and no issues with contrast or lack of clarity.
If I were advising someone considering mini-mono vision, I would tell them to consider setting the dominant eye to -0.25D and the other eye to -0.75 or at most -1D (so that there is no more than 0.75D difference). The reason I suggest the first eye be set just shy of 20/20 is because there can be an error factor and one could end up being slightly far sighted so I think it's better to go in just a little so as to not compromise too much near vision. Adjustments can then be made (to either the first eye or decisions about the second) after the first eye has been completed.
Good luck.
susan44499 michael74313
Posted
michael74313 susan44499
Posted
You asked how adjustments could be made to the first eye. So in other words - let's say you wanted the first eye to be -0.25D and the second eye to be -0.1D (a 0.75 difference for mini-mono vision) but there was an error factor and after the first surgery suppose the first eye turned out to be +0.5D (or slightly far sighted). at201 told me in another thread after a certain amount of healing (I'm not sure of the time frame but probably at least six weeks) that the doctor could perform a minor laser tweek on that eye and bring it in a little to where you originally wanted it at back to -0.25D. The laser is a lot more accurate in fine tuning the range you want compared to the surgery. So, that could be done after the first surgery and before the second.
On the other hand, let's say, the first eye turned out to be -0.1D rather than what you targeted at -0.25D. Then rather than do any laser adjustments at all, you might decide to just target the second eye to -0.25D (so you still have mini mono vision). I realize many might say that you are then not setting the dominant eye for distance. But, it's mini mono vision and both eyes are probably still working together. My eyes were targeted with a difference of -0.5D and my left "dominant" eye usually (but not always) sees a little better at all ranges. I'm not sure if that is due to it being dominant, healthier (I've had trauma in the past to my right eye), or if it's due to the toric lens shifting ever so slightly right after surgery (or maybe some combination). While I could possibly look at doing a laser correction to my right eye, overall my eyes see so well right now that my doctor feels I should not do anything at this time.