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IOL options for excellent intermediate vision even if helped by glasses/contacts

I have a mild myopic prescription (Left: -1.50,  -0.5 x 165, Right: -1.25, -0.5 x 25) with a +2 reading add and am trying to decide on IOL options that with or without additional glasses/contacts will give me excellent intermediate vision.

I spend many hours using large screens (software developer) and although I've worn multi-focal contacts for years their loss of contrast has been a growing issue as I've moved through low/medium/high reading add contacts. The problem with multi-focal contacts is although I can add glasses over the top for better near or distance vision, there is still loss of contrast and I cannot have astigmatism correction in the glasses as it just doesn't work with the contacts.

However I will soon need IOLs and although I would like to have something with a better range of vision than monofocals, I don't want to be in the same position I am with multi-focal contacts where the vision is impacted and nothing will improve it in the intermediate range.  I would rather juggle some extra glasses and contacts as long as that is an option.

From everything I've read this leads me to consider either:

a) Monofocal IOLs targeting for -1.5 or -1.75 and augmenting these with multifocal contacts or glasses.  So a similar position to where I am now but less the little bit of accommodation I still have.

b) The Tecnis Symfony targeting distance with reading glasses to boost the close vision.

So some questions specific questions but any comments appreciated:

1) Am I correct in assuming that using multi-focal contacts or glasses with astigmatism correction over monofocal IOLs should be fine?  

2) How well does using multi-focal contacts work over multi-focal IOLs and extended depth of focus IOLs?   I expect the first is a no go, but not sure is that holds true for Symfony IOL.

3) Can glasses with astigmatism correction be used over multi-focal IOLs and extended depth of focus IOL?     As per the last question I expect the first is a no but not sure for the Symfony IOL.

4) If I have a monofocal IOL targeting -1.5D how fast does focus tail off in either direction?  I am thinking of the loss of what little accommodation I have left and using phones/tablet etc.

5) How do the night time issues with Symfony  (halos/rings) compare to multi-focal contacts?  I appreciate it depends on which contacts but is it generally better/same/worse as I've found all multi-focal contacts have some effects which don't bother me too much.
4 Responses
Avatar universal
I'll break this into multiple posts. Your comments imply you have cataracts, which may be part of the reason you've noticed reduced contrast sensitivity over time (in addition to the increased adds), in addition to the reality that as we age our eyes need more light and contrast sensitivity declines with age. Just as with presbyopia, the issue may be less noticeable at first but eventually becomes noticeable. One study compared contrast sensitivity with a  high add multifocal IOL, +4D, with a monofocal and with the average of people in their sixties:

http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0068236

and shows both IOLS doing better, though with the multifocal fairly comparable to those in their sixties. (so perhaps not as good as someone your age, which I'm guessing from the add is less than that).  This article has old data, I don't know if there are more recent summaries, but indicates the decline in contrast sensitivity with age:

http://people.brandeis.edu/~sekuler/papers/owsleySekulerSiemsen_1983.pdf

Another paper is a reminder that monovision also reduces contrast sensitivity, in this case contact lens monovision didn't do as well as multifocal contacts:

http://www.academia.edu/24502544/Contrast_sensitivity_with_presbyopic_contact_lenses

I don't know which brand of multifocal contacts you use, oddly out of curiosity I checked and see one paper that doesn't refer to contrast sensitivity, but it does give an indication of visual acuity for different adds of an air optix multifocal:

http://www.ivo.gr/files/items/3/339/opo-multifocal_cls(13).pdf


The range of vision seems to be better in the data for the Symfony (or low add bifocal IOLs) than those. In terms of how far vision drops off from the best focal point of an IOL, that varies with the IOL and the person's natural depth of focus. Studies only give average (though sometimes a range, rarely a distribution). Often such information is contained in a "defocus curve" rather than a table, which is explained in these articles (I'm assuming since you develop software you can handle some math and data):

http://crstoday.com/articles/2010-nov/feature-story-get-to-know-the-defocus-curve/
https://millennialeye.com/articles/2014-jul-aug/understanding-the-defocus-curve-its-all-about-the-optics/

In terms of understanding what a particular visual acuity means in terms of what you can read, here is one chart giving visual acuity vs. print size and common examples:

http://www.teachingvisuallyimpaired.com/print-comparisons.html

There are charts online to convert logMar (often used on defocus curves) to snellen and other visual acuity metrics:

https://en.wikipedia.org/wiki/LogMAR_chart

Often  monofocal IOLs are included as control lenses in studies of premium lenses, so the Tecnis monofocal is included in charts of the Symfony's defocus curve, here are a couple of those, one from the EU site and then the US site:

http://www.tecnisiol.eu/tecnis-symfony-iol.htm
https://www.vision.abbott/us/iols/extended-depth-of-focus/tecnis-symfony.html



1 Comments
To try to make sense of the data, this might be of use. I just needed to do a conversion and ran into a calculator that converts between logmar and snellen acuity, to deal with values that aren't in the chart:

http://www.myvisiontest.com/logmar.php

Also I neglected to mention how to convert a diopter measurement to the focal distance in centimeters (and vice versa)  to get a better idea of how vision drops off. Here is the formula and table:


http://m1.wyanokecdn.com/3be04992acb9080d56b6e90c00dd5e96.pdf

and a calculator:

http://www.calctool.org/CALC/other/converters/fl_ls

(though since its just a simple division, i find it convenient to just do the calculation  myself since the Chrome browser lets you do arithmetic in the address bar, and even does conversions between units like inches to cm, so I don't even need to switch pages/windows/keyboards to do it).
Avatar universal
One issue you seem to be concerned about is astigmatism correction postop,  however you already have a low level of astigmatism and so it isn't clear how much if any you'll have postop. If you had corneal scans then you could ask the doctor's office for the results to see what they indicate about your level of corneal astigmatism (though scans they do for other purposes may not reflect posterior corneal astigmatism, which is usually minor but they discovered is useful to measure preop when planning).

Although most astigmatism tends to be corneal, there is sometimes lenticular astigmatism and   cataracts can add to that.  During surgery they either explicitly attempt to reduce your astigmatism by using incisions (often LRIs, limbal relaxing incisions) that cause your eye to reshape, or at least can try to plan the incisions for the surgery itself to be located to try to reduce astigmatism (rather than add surgically induced astigmatism).  

Here is one paper on the issue of how much astigmatism should be corrected:

http://pabloartal.blogspot.com/2013/10/what-is-minimum-amount-of-astigmatism.html
"These results provide a solid argument to leave small values of natural astigmatism, typically below 0.5 D, uncorrected in practical refractive and cataract surgery procedures."

I've seen other papers noting that people's brains do adapt to their habitual astigmatism, which seems to be why sometimes it isn't easy to adapt to prescriptions that alter it.


1 Comments
I should add that the most recent glasses prescription before my cataract became a problem included -0.75D for that eye, but the corneal scan only showed -0.25D in one, -0.17D in a more precise one, and postop the refractions are always 0D of astigmatism. The other eye had -1.5D of astigmatism on the refraction, showed -0.25D on one corneal scan, though -0.63D on the one preop, and  wound up at -0.25D at the most recent postop (using a spherical IOL, and merely planning the surgical incisions in the right way), though -0.5D in early postop refractions. That eye is at least 20/15 despite the astigmatism.
Avatar universal
To explicitly address the questions:

"1) Am I correct in assuming that using multi-focal contacts or glasses with astigmatism correction over monofocal IOLs should be fine? "  

Yes, though of course you'd likely use a high add multifocal contact lens with a monofocal set for distance, which may lower contrast sensitivity.

re: "2) How well does using multi-focal contacts work over multi-focal IOLs and extended depth of focus IOLs?   I expect the first is a no go, but not sure is that holds true for Symfony IOL. "

I haven't seen any information on that, I'd be curious if anyone discovers any. I had planned out of curiosity to try that with the Symfony but hadn't, I should consider doing so at least with one eye. The reason I hadn't tried is unfortunately my cataract  in one eye shifted my correction in that eye greatly preop, from -9D or so to -19D or so, and I needed to switch brands temporarily to get a high enough power and wound up with a GPC bump from the other brand that *still* hasn't gone away so I've avoided putting a contact lens in it.

It seems likely the multifocals wouldn't play well together., but then again  perhaps  the focal points multiply, e.g a bifocal with a bifocal winding up with 4 focal points and perhaps merging into a more continuous range. Obviously it would reduce contrast sensitivity and the range of light available at each focal point.


re: "3) Can glasses with astigmatism correction be used over multi-focal IOLs and extended depth of focus IOL?     As per the last question I expect the first is a no but not sure for the Symfony IOL. "

That shouldn't be a problem with multifocals or the Symfony.  I've been in contact with someone with a toric Symfony that wasn't oriented correctly and he was wearing   astigmatism correcting glasses temporarily until it was rotated. Again though, it isn't clear whether you'll need or want any residual astigmatism correction, and if you do then they can also consider doing an incision in another procedure.


re: "4) If I have a monofocal IOL targeting -1.5D how fast does focus tail off in either direction?  I am thinking of the loss of what little accommodation I have left and using phones/tablet etc. "

I addressed this one in an earlier post.

re: "5) How do the night time issues with Symfony  (halos/rings) compare to multi-focal contacts?  I appreciate it depends on which contacts but is it generally better/same/worse as I've found all multi-focal contacts have some effects which don't bother me too much."

Unfortunately I haven't seen   data on the issue, but I assume it is much lower just as it is compared to multifocal IOLs. In general I don't recall seeing data on halo incidence with multifocal contacts, I'd be curious if you see any. I think the issue is studied more for IOLs because people can't merely stop wearing them if a problem arises. I do see this article mentioning surprising figures:

http://www.envisionmagazine.ca/special-contact-lenses-can-help-avoid-car-accidents/
"The study, titled Needs, Symptoms, Incidence, Global Eye Health Trends (NSIGHT), surveyed 3,800 spectacle and contact lens-corrected subjects, 15 to 65 years of age, from seven countries (China, Korea, Japan, France, Italy, United Kingdom and the U.S.) to better understand the eye-related symptoms that vision-corrected patients experience. The NSIGHT data provided valuable information on how often patients experience halos and glare and the degree to which they found them bothersome.

About half of the spectacle and contact lens wearers surveyed reported suffering from the symptoms of halos (52 per cent and 56 per cent, respectively) and glare (47 per cent and 50 per cent, respectively) more than three times a week. More than four of five patients who experienced these symptoms found them bothersome (84 per cent and 89 per cent for halo and glare, respectively). "

Presumably most of those except some fraction of the older ones aren't even wearing multifocal correction.

I never really noticed any problems with multifocal contacts. My night vision is definitely better overall with the Symfony than I can recall it being even before cataracts, partly due to less glare disability from headlights, their brightness isn't as distracting for some reason, they don't distract from seeing the surrounding areas as much as they used to. So although I am in the minority that see halos with the Symfony, the mild translucent halos that I see through past/through are more then compensated for by less glare disability, and by having better visual acuity than I can remember having (which is sometimes the case for high myopes partly due to getting rid of the minifying effect of the correction they wear).

2 Comments
Avatar universal
Thanks SoftwareDeveloper for the detailed replies.

I currently do not have cataracts, just severe floaters which have got to the point I am considering FOV despite the risks as they affect my work.  One of the surgeons I have seen normally combines FOV with lens replacement and posterior capsular lasering. This is because he believes that cataracts are inevitable within 2 years at most for patients of my age (52) and wants to minimise risk of further floaters.  I will be posting some other questions about that aspect but want to think about IOLs as clear lens replacement was not my expectation with FOV even though I know the cataract risk.

Despite my age I still have good contrast sensitivity and that's why I think I am sensitive to the drop with multifocal contacts versus glasses.  I've tried more than 10 types of multifocal contact as many suffer from poor intermediate focus but currently use Alcon Dailies Aqua Comfort Plus.  These are good with minimal night time effects, it's just small text on large monitors is harder to read and glasses with just the minor astigmatism correction don't improve matters (it varies between contact lens design but these are the best otherwise).

Biometry showed -1.1 left and  -0.65 right eye astigmatism so not quite in line with the glasses prescription allowing for their different distances so perhaps the lens is offsetting this (or rear of cornea).   The surgeon said he's not sure the left is enough for a toric IOL but he may be wanting to reduce the risk with positioning and capsular lasering and this is why residual astigmatism is a concern.
10 Comments
re: "This is because he believes that cataracts are inevitable within 2 years at most for patients of my age (52) "

I'm not sure if he means that is likely after  the proposed surgery  (which I haven't looked into, though it seems odd), otherwise the average age when cataract surgery is needed is in the mid-70s or at most early 70s, mine was very atypically early. Though the lens does degrade with age, they call it "dysfunctional lens syndrome" and the beginning of a cataract can reduce contrast sensitivity before it gets to the point when surgery is required.

For that level of astigmatism, some surgeons still do prefer incisions, especially if the use laser incisions. However it does sound like you don't know for sure how much astigmatism you have.  Unfortunately I haven't had any reason to research FOV so I have no idea how that would impact the procedure or the choices.


Although you say you have good contrast sensitivity, I'm wondering if the floaters are interfering with that in real world vision. I wore multifocal contacts in both eyes, Acuvue and then Air Optix until age 49 when the problem cataract appeared in one eye, and then kept a multifocal contact in my good eye (single vision in the cataract eye) until age 52 and surgery, and I had no trouble with contrast sensitivity for using the computer with default fonts (24" monitors at perhaps 26", 1920X1200), or smarphones.

I definitely noticed the lower quality of vision dim light with multifocal contacts, and the Symfony is much better in terms of that.

Also, oops, I took another look at the paper above on the air optix multifocal, I'd just done a quick glance before, and it looks like the high add might have a better defocus curve than the Symfony, but with the obvious drop off in contrast sensitivity.

I didn't see a comparison between IOLs and multifocal contacts in terms of contrast sensitivity. However  I did run into a comparison of the contrast sensitivity of an aspheric monofocal IOL to those with natural lenses:


http://crstoday.com/articles/2015-may/a-primer-on-aspheric-optics/
"A Primer on Aspheric Optics
Aberrations and visual quality with current IOLs.
... Figure 1. Patients implanted with an aspheric IOL demonstrated peak mesopic contrast sensitivity similar to that of phakic 20- to 30-year-olds and superior to that of both patients implanted with a spherical IOL and phakic 30- to 50-year-olds. "


The Symfony has contrast sensitivity fairly comparable to the Tecnis monofocal, but unfortunately I haven't seen it compared on the same graph or with numbers in the same units vs. natural eyes or multifocal contacts.
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re: "small text on large monitors is harder to read and"

Obviously I assume the issue is using small text wishing more lines visible on the screen at once. To to make up for enlarging the font, had you considered springing for larger (possibly higher res) monitors, or more monitors, perhaps rotating  one or more  monitors to  portrait? (a bit lower risk and cheaper than surgery).  

I'm one of those developers that likes lots of screen space (I know some don't care about that) so I can understand disliking the idea of increasing font sizes or page zoom levels  and reducing the amount visible at once. After one monitor died, during the the last Black Friday sales I got a cheap 40" 4k TV to replace it. (only some 4K tvs are suitable for use as monitors).

For some uses   I discovered that larger fonts than the default may be more productive, despite the frustration of having fewer lines visible on the screen at once. I found these papers discussing reading speed vs. font size (which of course is font size based on visual arc rather than pixels since it depends on how far away the monitor is):

https://www.imarc.com/blog/best-font-size-for-any-device#fn:1

http://jov.arvojournals.org/article.aspx?articleid=2191906

I haven't found a good source to figure out how much the issue of pixelation impacts that. I'd found another article with a spreadsheet that lets you figure out how far your monitor needs to be, based on your visual acuity, to make it "retina", but I tend to not have them that far out:

https://www.pugetsystems.com/labs/articles/Can-you-see-the-difference-with-a-4K-monitor-729/

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Thanks again for all the information.

The reference to getting cataracts within 2 years is purely related to the vitrectomy as that is its main downside of the procedure as it greatly accelerates this happening.  Statistics are difficult to compare as the likelihood varies depending on length of operation, reason for vitrectomy, how close the surgeon works near to the lens, age and just individual differences as with cataracts normally.

For people in their 20s and 30s they could be lucky and go 10 to 15 years without a cataract post vitrectomy but at 50+ the odds are far worse and the cataracts can progress very quickly and a statistic I've been told by several surgeons is 80% get cataracts within 2 years at my age.

However potentially combining vitrectomy with lens replacement and also potentially with posterior capsular lasering is a lot to decide as there are lots of permutations and risks. It doesn't help that different surgeons have different recommendations!

My key question about IOL and quality of vision is really to just avoid the same 'average at all distances but great at none' that multifocals contacts often provide.  Your point about floaters affecting contrast more than I realise could well be the case as I was surprised when I saw these figures:

http://www.vmrinstitute.com/wp-content/uploads/2014/06/FLOATER-VITRECTOMY-Retina-2014-final.pdf

My floaters started several years ago so its impossible to remember my vision before.

I currently use 3 x 27" monitors 2560x1440 with standard font scaling so am pushing things a little.   I've been thinking of a main 40" monitor and 4K for easier scaling for a while so maybe time to go that route generally.
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In terms of multifocal contacts being average at all distances but great at none, in my case I definitely feel vision is better overall with the Symfony than with multifocal contacts. I guess part of why I chose this over a trifocal was because it appeared to be great at intermediate and distance, even if not quite as good at near as multifocal IOLs. Its chromatic aberration correction balances out the extension of depth of focus to yield still  great distance and intermediate.

I suspect even multifocal IOLs which use different optics will be better than multifocal contacts.   Since I was happy with multifocal contacts, when my problem cataract appeared, I naturally looked into multifocal IOLs and discovered that at the time the US  had only approved high add bifocal IOLs which had a noticeable drop at intermediate, which was a problem for  using computers but also for social distance, household tasks, etc. So I considered going for a trifocal outside the US, which does a better job at the whole range of vision, but decided as I said on the Symfony in part due to better intermediate, and lower risk of night vision issues. There are now low add bifocals in the US,  which have less of a drop at intermediate than the high add ones, but still not quite as good as the Symfony.

I saw one presentation I neglected to save a link for, from I think Dr. Holladay, who suggested that although aspheric monofocals in theory  based on optical bench data can provide better distance correction, that typical results in the real world are like 20/17 for an aspheric monofocal and 20/18 for the Symfony (though I'd seen one study showing the Symfony having slightly better distance acuity than the control monofocal, while most put them at tied within margins of error with perhaps a slight edge for the monofocal), and I have at least 20/15. He listed 20/20 for a spheric monofocal (rarely used now) and 20/22 for a typical diffractive multifocal (though I think the some newer ones may be better). Its unclear most people will notice those differences, but I certainly doubt they would with the Symfony.

In reality of course you aren't typically looking at infinite distance, or even far distance, and so in practical terms the extended range of vision with the Symfony would likely win out. Of course each person's priorities are different. In my case I'd worn correction all my life as a high myope, and liked the idea of rarely needing correction the rest of my life.

In terms of monitors, unfortunately the best prices on 4k TVs are around black friday. One issue is that the top of it on my desk is sort of high compared to the highest my chair goes, I'm considering abandoning my desk for a floor mount for it with a stand for the keyboard.  After the fact I decide I wished I'd actually gone for a larger screen I could have located further out while still being the same perceived angle. Apparently ergonomics folks recommend locating the monitor further out since the resting point of convergence of the eyes, the angle they'd ideally point at rest to give lower eye strain, is more in the range of 39-45 inches (I've seen varied estimates), and further out yields better visual acuity even with the Symfony (for those with their natural lens, the resting point of accommodation also suggests locating monitors further out), I ran into this page that lets you compare the perceived size of objects, like a monitor or a font, located at different distances:

https://sizecalc.com/
Oh, also, one issue with the 40" screen though is that you do see things on the side of the screen at a bit of an angle.   I'm actually wondering about getting a floor stand and rotating this to portrait mode, if the vertical angle difference would be better than when its horizontal. Unfortunately I wasn't ready to spring for a curved screen (and I'm unsure if the radius of curvature is useful or not).  I'd seen articles like "4k is for programmers" so had been debating about it for a while before I finally went for it, partly since you can get 60hz refresh now on TVs as monitors,  and I doubt I'd have gone for the older ones with just 30hz. Due to the issue of angles on the edge, if I'd been ready to spend more  I might have considered returning it for some other arrangement with more monitors.
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