Disadvantages of the Different IOLs Types

[kcengage]

I live in Canada, and my grandfather needs to choose an IOL.  Obviously, each of the respective company's website has the benefits and advantages but what are the disadvantages:

Multifocals i.e. Alcon Restor, AMO Rezoom and Technis
Accommodative Lens i.e. Crystalens

Thank you!

[SoftwareDeveloper]

Since you are highly myopic (though that is usually determine by the axial length measurement) there is a higher risk that they will get the IOL power wrong for various reasons since the calculations aren't an exact formula. They are based on statistics for prior patients based on how well the lens power worked for them compared to their eye measurements. It may be that high myopes aren't common so there is less data on them to refine the formulas, or some suspect there may actually be errors in the instruments used to measure highly myopic eyes. Here is an expert on the field talking about the topic who suggests a better approach, but who does say that one approach is to:

http://www.doctor-hill.com/iol-main/extreme_axial_myopia.htm
"Target a moderate amount of myopia. (What most people do.)"

That seems to be the result that your surgeon is aiming for. He does suggest better alternatives (and will consult with surgeons on lens power choices), but there is still the chance of an error with any of them. So I think some experienced surgeons would use those corrections and not target quite as yours is doing, it is a common strategy that may make sense. I do gather that laser myopic correction is easier than hyperopic correction, but for a small amount I'm not sure it makes much difference (I hadn't looked into laser enhancement in detail since I'm not considering it yet).

. My -9.5D (before cataracts) eye wound up +0.5D or so, slightly hyperopic, whereas I would have preferred any error to be myopic to give me better near vision. I may consider a laser tweak in the future to -0.5D or so for that eye (the other eye was less myopic and wound up plano, 0D).

The cylinder value is the level of astigmatism, how much your eye is shaped more like an American football rather than a sphere. If the cylinder is 0 then your eye is spherical and doesn't need correction. Otherwise it means that in one direction the lens power of your eye is given by the sphere measurement, while at an angle from that your the lens power of your eye is (sphere-value + cylinder value).

Toric lenses can possibly rotate, but most don't and if they do most of those can be rotate back into position. To me the idea of correcting the eye on the cornea with laser/incision makes sense since that is where the astigmatism is. However most surgeons seem to be leaning towards toric lenses above a certain amount of cylinder, but the amount they choose varies. Fortunately I didn't have enough astigmatism to need to consider a toric lens, but since I get questions now I did save some links on the topic.
  
If you check articles on the topic of when to use a toric lens  (in publications like CRSToday and CRSToday Europe, Eyeworld, etc), the guidelines surgeons pick tend to vary. The -1.25D is in the range where many would go with incisions/laser but others would to toric lens. Most surgeons I have seen quoted would put -2.5 of cylinder at the level that they prefer to use a toric lens, but not all, some do use them to higher levels.  One Czech surgeon uses incisions instead up to -5D.  Here are a few articles on the topic:

http://www.reviewofoptometry.com/content/d/cataract___and___refractive_surgery/c/51403/
http://crstoday.com/2014/05/correcting-corneal-astigmatism-with-laser-incisions/
http://crstodayeurope.com/2013/01/state-of-the-premium-iol-market-in-europe
http://crstodayeurope.com/pdfs/0313CRSTEuro_bf2_Astigmatism.pdf
http://crstoday.com/2013/05/preoperative-planning-for-toric-iols-and-limbal-relaxing-incisions/
http://crstoday.com/2014/05/todays-peripheral-corneal-relaxing-incisions/
http://crstoday.com/2013/10/toric-lens-or-astigmatic-keratotomy/
http://www.medscape.com/viewarticle/747025

There is one doctor that has directly compared the Symfony with the AT Lisa trifocal, this is the study that I saw that first made me wonder about the Symfony rather than the Zeiss AT Lisa Tri, unfortunately it is a small study:

http://crstodayeurope.com/pdfs/1014CRSTEuro_cs_Hamid.pdf
http://ophthalmologytimes.modernmedicine.com/news/vision-all-distances

So I have to wonder if that accounts for some of the differences. Minor statistical variations are likely due to things like surgical technique and that the constants they use to determine the lens power get more accurate over time as a surgeon has used a lens more (and the Symfony is new), this more recent article shows some slight differences in uncorrected acuity that I hadn't seen mention of before that I'm suspecting aren't statistically significant:

http://www.opticianonline.net/presbyopia-surgical-management/

[Aali07]

Thank you so much for responding. Despite the very little detail I was able to provide, you have been very helpful.

What was meant by -2
The consultant said, after placing the zeiss tri 839mp lense My vision will be -2 not -1 because it's easier to perform the lasek suregery at -2 to correct my astigmatism?

I don't know the severity of my astigmatism but my prescription at the moment is
Right eye         sphere -7.50.       Cyl -2.50
Left eye.                      -11.50.            -1.25

The cataract being the worst in my left eye. Prior to that it was roughly -8 for my left eye

My consultant wasn't too keen on toric lenses for me. He said that previous  have complained about light sensitivity day and night as well as seeing halos and four moons!! I don't work at night although I do drive home in the dark during winter.

Call me a paranoid but I'm wondering could he be suggesting lasek to correct astigmatism instead of toric as it's supposedly easier. I read topics r difficult to position. And of course it will cost me more to have the cataract surgery, premium lenses and lasek on top of all that.

Any advice you can give me will be much appreciated. My surgery is booked for Thursday!!!

Thnx
Aali07

[SoftwareDeveloper]

re: "-2 trifocal lens"

I don't know what the "-2" refers to, is that the IOL power? A minus lens power in an IOL isn't very common except for very extreme myopia, even most high myopes wound up with a + power lens for an IOL (even if their prescription for glasses/contacts is negative).

re: "lasek surgery to correct my astigmatism"

It depends on how much astigmatism you have what method they use to correct it (they should be able to tell you the total corneal astigmatism). If it is a small amount sometimes it is corrected with incisions within the surgery itself, LRIs (limbal relaxing incisions) or some other type of  incision. If it is a larger amount often surgeons think a toric lens will  more accurately correct astigmatism. Conceptually since the astigmatism is on the cornea it makes  sense to me to correct it there with an incision, but surgeons overall seem to think for larger amounts a toric lens is a better option.

re: "advised correctly"

It depends on your visual needs and how much you wish to avoid the need for wearing correction afterwards and for what distance.

There is no IOL that is perfect now unfortunately, they all have tradeoffs. A trifocal lens is a good overall candidate for those who wish to avoid the need for vision correction afterwards since it gives decent vision at all three major visual ranges: near, intermediate and distance. There is a new extended depth of focus lens, the Symfony, which seems likely to give better intermediate visual quality than the trifocals at the risk  of not quite as good very near vision. I was initially considering a trifocal until the Symfony came out and I decided that I spend more time at intermediate distance tasks (on the computer, social distance, or household tasks) than very near tasks so it was a better bet for my needs.  I wound up 20/25 at near (and if I did a laser touchup for a bit of mini/micro monovision I might be 20/20 at near).

Trifocals tend to have a lower risk of issues like problems with halo&glare than older multifocals, but there is still a risk of issues with those, and with reduced contrast sensitivity. So for instance someone that drives a taxi at night for a living might not be the best candidate to risk getting a multifocal. The Symfony reportedly has comparable contrast sensitivity to a monofocal as well as a risk of issues with halo&glare comparable to a  monofocal.

I should make the caveat that I don't know which trifocal you are talking about. There is a new Alcon Panoptix trifocal that was just approved in Europe a few weeks ago, but I have seen no data at all on it to know how it compares to the other trifocals, but I'm guessing it would be comparable to the Finevision and AT Lisa tri which are the common trifocals in use now.

[Aali07]

my consultant has advised -2 trifocal lense and lasek surgery to correct my astigmatism.  Have I been advised correctly? I am 35 and have cataracts in both my eyes.  (God knows!!!) I have been shirt sighted all my life and have a very strong prescription. I would really like to be free from glasses. Please advice.

[YoGranB]

I have astigmatism problem and need bilateral cataract surgery. Which lens would be recommended? Is it most important to correct the astigmatism ie
The toric IOL

[Ray T Oyakawa, MD]

Tetraflex is not yet FDA approved in the U.S.  I have not experience with it.

Premium lens means non standard (not paid for by Medicare or most insurance companies).  They are toric and presbyopia correcting IOLs.

Dr. O,

[kcengage]

What about the Tetraflex?  I have read some forums on this lens that it is available in Canada?  By the way, what is a premium lens?  Better lens?

[Ray T Oyakawa, MD]

You are correct about glasses.  I have a few patient who use plano glasses in public and use no glasses at home.


There was an episode of Sopranos where the incarcerated character wanted to see his optometrist before appearing in court and did not
want to look weak.

Dr. O.

[JodieJ]

The poster's grandfather could easily be in his early 60's.  I certainly wouldn't view someone that age as "elderly" (not anymore, in any case).  Premium IOLs are largely tested on and marketed to people over the age of 60.  (The aging Baby Boom population is obviously a big incentive for research in this area.)  I'm not really sure why, but glasses seem to be viewed as a cosmetic defect by many people of all ages.  Personally, I disagree with this perception--as long as the frames are flattering and not outdated and the lenses are made of higher index material (for strong prescriptions).  And it's been shown that people wearing glasses are perceived as being more intelligent than (the same) people who are not.  That's why it's sometimes recommended to wear your glasses (not your contacts) to job interviews.

[Ray T Oyakawa, MD]

The key is the surgeon and his experience.

All IOLs have better results when target is achieved and astigmatism corrected.

Success with premium IOL start with patient selection.  The patient visual needs(preference for glasses or not, if so what distance one wants to minimize glasses use), an eye with potential for good vision-patient may not be a candidate for certain IOLs due to ocular disease besides cataract.

Next, the experience of the surgeon with all types of IOLs and LASIK or PRK surgery.


There is an IOL which can be adjusted by laser post operatively to correct residual refractive errors.  I do not know if is multifocal.

Search this list for the types of IOLs you are interested in and then consult with your surgeon.

I have successful patients with Torics, Arrays, ReZoom, ReStors, and Crystalens.  Each have their advantages and disadvantages.

The biggest challenge with multifocal IOLs is the ability for the patient to neuroadapt.  This can not be determined preop.  Also, if macular disease occurs in the future vision will be compromised.  The Crystalens IOL does not have these problems but is much more challenging for the surgeon to implant, hit target, and manage postoperatively.  

Dr. O.

[ace399]

Should kcengage's grandfather's age be a factor in his decision?  There are hardly any complaints in this forum on single focus IOL's.  If he has not been myopic, why not just implant standard IOL's set for distance and use reading glasses?  If he's been myopic and has enjoyed good near vision without glasses, then why not set the fixed IOL to near vision and use distance glasses?

I get the impression that multifocal IOL's, although not perfect, can be a better choice for younger people or older people who are active, say in sports.  There are definitely more risks with multifocal IOL's.  We're probably going through a period where they are continuing to be improved.  I've heard that there are multifocal IOL's under development that can be adjusted while in the eye!

[peakhope]

Search this forum for each lens type to find people complaining...those will be your most worrisome disadvantages. Try to distinguish between cases where this specific person had an unusual issue, cases where the doctor got something wrong, cases where a more widespread/general problem is involved, and cases where the patient may have had unrealistic expectations.

Eliminating most if not all astigmatism should be a goal with any IOL, not just premium lenses. However, residual astigmatism may cause even more problems with certain premium lenses. The one possible exception is that some "against the rule" astigmatism can have the odd benefit of increasing perceived accommodation for reading with  monofocal lenses, according to one study.

With monofocal (non-premium) lenses IOL, glare is a serious problem for a small percentage of people. It is a bit more likely with Crystalens, more likely with Restor, and much more likely with Rezoom. (I'm not sure where the Technis fits into that spectrum.

My understanding is that the Crystalens is the most difficult to install, and to hit the target refraction, so having an excellent surgeon is even more important with this lens. And according to some, but not all, doctors, Crystalens patients may be more likely to require a yag laser capsulectomy procedure.

Beware of how the manufacturers cite statistics in ways that exaggerate their benefits. For example, consider the percentage of patients who "reported never wearing glasses following cataract surgery in both eyes". This would not take into consideration people who have vision problems (such as glare or "waxy" vision) that are not helped by wearing glasses.

When studies are cited, they often only count patients whose outcome was pretty close to their refraction target. That means that the statistics don't even count a group of patients whose sight is not what they wanted. Finally, they usually compare the results to monofocal lenses, and not to other multifocal/accommodating lenses.

Remember that if 96% of patients are happy or would choose that lens again, that means that the rest are unhappy and would not. You might be one of those unhappy ones. On the other hand, with monofocal lenses you run a very high (90%?) risk of needing glasses for at least certain distances. And a monovision configuration of monofocal lenses would be risky if monovision contact lenses are not tried first.

[Disclaimer: I am a happy Crystalens HD user]

[JodieJ]

I can think of a few disadvantages.  To start, if the surgeon cannot come close to achieving the targeted refraction or eliminating astigmatism, vision can be unsatisfactory at ALL distances with any of the premium IOLs.  Based on numerous posts by unhappy patients, hitting the target seems to be a problem for many surgeons implanting premium lenses.

Disadvantages of multifocal IOLs include less-than-crisp distance vision, possible ghosting or "waxy" vision, impaired intermediate vision (ReStor, Tecnis MF), inability to read (more than a restaurant menu)without glasses (ReZoom), impaired night vision due to glare, halos, starbursts (which may be permanent), and the possibility that the recipient simply cannot neuroadapt to multifocal vision.

The Crystalens HD should provide excellent distance vision (every bit as good as what you'd get with a monofocal IOL) if the surgeon can reach the targeted refraction and astigmatism is eliminated.  The major disadvantage involves the possibility that the IOL won't accommodate as advertised, resulting in a need for glasses to read or to use a computer (just like what you'd get with monofocals).  Some Crystalens recipients have had major problems with glare and halos.  The Crystalens also lacks adequate UV protection.