Large pupil and positive dysphotopsias

Thanks a lot for the detailed response, Ron! I really appreciate your feedback. The paper that you linked is extremely useful (even if it the data is not always conclusive).

One thing that seems well supported is that larger IOL diameter is associated with fewer PD:

"PD occurrence may also depend on the IOL diameter. Bournas et al. found that a smaller IOL optic diameter is associated with higher odds of optic phenomena. Specifically, 5.5 mm diameter IOLs were linked to an increased risk for dysphotopsia compared to 6 mm diameter IOLs [13]. Similar findings were described by Bonsemeyer et al. that found 7 mm diameter IOLs to reduce both PD and ND incidence compared to 6 mm diameter IOLs [10]."

This brings me back to my question whether it might be safer for me to opt for the 7mm ASPIRA-aXA from HumanOptics. Here are the pros and cons I see vs the enVista:

Plus: 7mm optics, refractive index of 1.46 (vs 1.54 for enVista)

Minus: Not as well tested (even though initial studies look promising), hydrophilic acrylic (which seems to increase the odds of PCO)

Based on my the paper you linked, refractive index of the material did not seem to make as much of a difference in practice. So, the main benefit that I see would be the 7mm optics.

As for the target of -0.5D, I agree that this is a bit on the conservative side (in my case it actually ends up being -0.59D based on the calculation sheet for the enVista). The reason why I'm still considering going with this option are twofold: On one hand, it limits the amount of monovision as my other eye (which doesn't seem to suffer from any cataract for now) is at -1.75D. The other reason is that I have been myopic for so long that I'm kind of used to wearing glasses if I really need to see well into the distance (I'm a bit scared of cutting it too close and end up being hyperopic).

BTW: Do you know whether the predictions on the IOL sheet are spherical equivalents or just the sphere? I.e., if I currently have a cylinder of 0.75D and target -0.59D on the IOL sheet (non-toric lens), does this mean that the expected sphere will be -0.59?

I think targeting -0.59 D is excessive, and not necessary when using the modern more accurate formulas like Barrett Universal II and the Hill-RBF 3.0. You can find both on line. As I mentioned in an earier post I think it is very "short sighted" to target an IOL eye to match a natural eye which will need an IOL probably sooner than you may think. An IOL is pretty much a lifetime decision.

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And yes all the IOL formulas that I have worked with that are not for toric calculations will use spherical equivalent. So if you leave significant cylinder uncorrected that will impact the calculations and predicted outcome. They also base it on the cornea plane like an eyeglass prescription. Only the IOL powers are based on the lens plane. A 0.5 D change in IOL power has about a 0.375 D impact at the cornea plane. On the IOL calculation sheet the cornea plane value is commonly call the Reference D, or Ref D.

Thanks a lot for this information. I have had the same thoughts about probably needing PCO either way (sigh), but I wasn't aware of the advantages of hydrophilic acrylic that you mentioned. Given all of this, I feel that the ASPIRA-aXA might be the way to go for me. I don't think that my surgeon has any experience with it, but I will definitely bring it up.

I am planning to get the ASPIRA-aXA but I'm in the US so I am traveling to Europe to get it. I can share more about the experience after my surgery.

Just FYI there is a risk of calcifications with hydrophilic IOLs in very rare cases where patients have other eye disease that require certain procedures where exogenous gas or air bubbles are injected into the eye AND those bubbles somehow come into contact with the IOL. Even when that happens the IOL will not necessarily develop calcifications as the development is multifactorial. But it has happened, so if someone brings up calcifications that's what they are talking about

This is really interesting! I'm from Switzerland but have been living in the US for a few years, so I have been considering getting the cataract surgery in Europe as well. Do you already have a surgeon picked out and when are you expecting to have your surgery?

I noticed Jascha Wendelstein, who is the first author of a ASPIRA-aXA paper (Rotational Stability, Tilt and Decentration of a New IOL with a 7.0 mm Optic) is doing cataract surgeries at a place in Zurich, so I have been considering contacting them but haven't gotten around to do it.

BTW: Are you planning to go to Europe because the ASPIRA-aXA is not FDA approved or are you trying ton find a surgeon who is more experienced with this lens?

As another datapoint, I just stumbled upon a 2022 study about early onset PCO (~1,000 eyes):

Early-Onset Posterior Capsule Opacification: Incidence, Severity, and Risk Factors

Xiaoxun Gu, Xiaoyun Chen, Guangming Jin, Lanhua Wang, Enen Zhang, Wei Wang, Zhenzhen Liu,corresponding author and Lixia Luo

It has some interesting findings:

1. Age was not a major risk factor
2. PCO incidence was slightly lower in hydrophilic IOL than that in hydrophobic IOL

The authors note that the second point contrasts other research and explain it with the following hypothesis:

The main reason may be that 95.02% of hydrophilic IOLs used in this study were 360° enhanced sharp-edged hydrophilic IOLs. Koshy et al. ascertained that 360° enhanced sharp-edged hydrophilic IOL had a better capsular bag performance, and a lower PCO incidence than sharp-edged hydrophobic IOL in the 2 years after cataract surgery though PCO scoring showed no statistically significant difference between the two groups [29]. These results suggested that the design of IOL may be more important than the material in reducing the incidence of PCO.

All of this makes the ASPIRA-aXA sound like a really good option for people with large pupils.

I found the surgeon first, and the surgeon recommended the IOL. Like you I was consulting experts to try to find out as much as I could about different IOL options and what would be best for my specific situation. My pupils are not as large as yours and I hadn't even thought about that aspect of the surgery. I have extreme myopia and my cataract surgery will therefore be high risk. I found a surgeon in Europe who was very experienced with high risk surgeries and who recommended the ASPIRA-aXA because of its excellent optics and stability in highly myopic eyes.

Of course I would prefer to get surgery closer to home but I'm going to be living with the outcome of this surgery for the rest of my life so I decided it was worth the inconvenience.

The IOL is not FDA approved, but it is a good brand, German made. I personally think the FDA approval process is a barrier to innovation in medical devices in the US.

Keep in mind there are studies which concluded that the real rate of necessary YAG for PCO is in the order of 8%. But, yes, the risk of needing it increases with time, but I think it makes sense to delay YAG as long a possible.

And surface opacification of silicone lenses is a risk too.

It's really good to hear that your surgeon recommended the Aspira-aXA independent of the pupil size. This is another reason why I think that this lens might be the best trade-off for me.

Thanks for the encouragement. I did spend a lot of time reading about this topic and this forum has been invaluable, so thanks a lot to everyone for contributing!

You raise an interesting point about the residual corneal astigmatism. Based on the IOL master measurements, the 17D enVista IOL would put me at -0.59D. Are you saying that this is a spherical equivalent, which means that 0.5 * 0.75D = 0.375D would come from the residual astigmatism and the predicted residual sphere is only around -0.215D? If yes,do you know how this plays with my surgeons plan to reduce the astigmatism by strategically placing the incisions?

which means that 0.5 * 0.75D = 0.375D would come from the residual astigmatism

I infer that you are planning for 0.75D residual astigmatism. Why? Why not target zero? Why not use a toric lens aimed at neutralizing the cyl?

I think your surgeon's approach is excellent-- I mean why not place the incision such that any surgically induced astigmatism (SIA) will reduce residual corneal astigmatism. That being said with such a small incision there shouldn't be much SIA at all, and this type of astigmatism management is not really a precise science so I don't think there's any way to predict exactly where you will land after your eye heals.

It's my understanding that the refractive target includes the astigmatism in just the way you describe. So if you target plano but with 1D of astigmatism, then you would have one part of your eye at -0.5D and the opposite at +0.5D. However I think since you are under 1D of astigmatism, it's not really that much astigmatism to worry about in terms of visual acuity. I am no expert, but I think between 0.5D and 1.0D is where it starts to affect vision but not by much, and over 1.0D is when it starts to be annoying.

Another thing to be aware of is astigmatism is not stable over the long term, i.e. we all experience astigmatic drift as we age. So in ten years your astigmatism will be different from where it is now. Astigmatism generally drifts from with-the-rule to against-the-rule as we age, but how quickly and exactly how it occurs varies so much between individuals that is not possible to predict where you'll be in ten years. The change is gradual, but the fact that it will drift makes me feel like it's less important to try to correct small amounts of astigmatism.

We were considering a toric lens, but my surgeon thinks that for my small (and somewhat irregular) astigmatism there will be a more reliable outcome (especially over time) if we go with a non-toric. My surgeon believes that we can get the astigmatism to ~0.5D with the right incisions. Even with a toric lens, it's not a given that we would be able to go lower considering the irregularity of the astigmatism, difficulty of hitting the right angle / rotation, and the changing nature of astigmatisms.

Sorry, I can't agree. Compromising the target on your first eye based on the second eye which will need cataract surgery at some point, probably sooner than one expects, is not a good strategy. Cataract surgery is a once in a lifetime opportunity to correct your vision, and should not be compromised with "short sighted" decisions. It makes sense to make long term decisions, especially at a younger age like the OP.

With all the IOL calculation formulas that I have seen the outcomes are displayed in spherical equivalent, unless it is a toric calculator, and in that case it will display sphere and cylinder, leaving you to calculate the SE. Some calculators, and from memory, I believe the Barrett Universal II, accepts a surgical induced astigmatism factor, and allow entry of where the incision will be made.

FWIW my surgeon hedged his advice about needing a toric lens due to my astigmatism being irregular. I have seen the topographical map of my eye done with the Pentacam and it certainly is irregular. In the end I decided to go non toric, and I now have 0.75 D astigmatism. My vision is pretty good, but the optometrist has shown me what my vision is like with and without cylinder correction using the phoropter. It is a night and day difference. Much sharper with the cylinder correction. I now really regret not getting a toric lens. My surgeon offered to exchange it for a toric lens, but I declined due to the risk of a lens exchange. But, for sure if I had a "do over" I would choose a toric. It may not be the perfect solution to correct an irregular astigmatism eye, but it is sure better than nothing. And again FWIW I have investigated Lasik and PRK, and that turned out to be a dead end road to correct the astigmatism. It would have left me less myopic and I need the myopia to read with this eye.

Well said. Thanks for sharing.

Further on the toric lens option, based on my experience, I would ask to see what your current vision looks like with and without astigmatism correction. They can do that with the phoropter. It is not a perfect simulation of what a toric IOL could do, but it should be a reasonable estimate. If astigmatism correction with a phoropter does not work then a toric lens is not likely to work well either.

Thanks, Ron. This is really good advice. I'll definitely look into the toric options some more.

As for the target I'm still a bit torn about whether I should go for something more ambitious than -0.5D (or -0.59D in the specific case of the enVista). I agree with your point that I will almost certainly need cataract surgery in the other (left) eye earlier than later and therefore should not put too much emphasis on this.

But even when I can choose the target for my left eye, I feel that I might prefer trading a bit of distance vision for close vision. I currently have -1.75D in my left eye and feel that this is barely sufficient to work on my phone comfortably (it may have to do with my large pupils). So, I don't think that I would want to target any less than that for my left eye. Given that I prefer to keep monovision at ~1.25D or less, This puts me at -0.5D for the right eye. This is still far better distance vision than what I had for the last 30 years of my life, which makes me feel quite comfortable.

The standard guideline for differential between the eyes is 1.50 D. If you target and ideally end up with -0.25 D in your right eye, that means up to -1.75 D in your left eye. That is pretty much where you are now at -1.875 D SE in your left eye. You will get a eyeglass free trial of mini-monovision. It will be a little optimistic as at your age you will likely have some accommodation left.

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You need to see the IOL calculation sheet for a more accurate number, but I would guess the next higher power IOL than the one that gives -0.59 D will be in the range of -.215 D. That is about as close as you can get to the standard target of -0.25 D. You can get some more comfort around that prediction by getting the IOL calculation sheet data which will have your eye measurements and then enter the data yourself . If you google this you should find a multi-formula IOL calculator where you can enter your eye measurement data once and then see the results from about 7 different calculators. It can be done with a toric lens calculation as well, but with fewer formulas. In the non toric category, I would put most faith in the Hill-RBF 3.0 formula followed by the Barrett Universal II. For torics then the Barrett Universal II.

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ESCRS IOL Calculator

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I think it makes most sense to look at this as a process. Do the right eye for full distance, and then simulate various amounts of myopia for the second eye. You probably will have lots of time to do that. There is no rush. You can use contacts to simulate more or less myopia in the second eye, and can even use OTC readers with your IOL distance eye to get a more realistic accommodation free view of what myopia you need with an IOL eye.

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Keep in mind if you plan to use the left eye for nearer vision and you sacrifice distance with your right eye, there is no way short of eyeglasses, contacts, or Lasik to get the distance back again.

Thanks again, Ron! This is really helpful and gives me some stuff to think about. Will get back with an update as things develop.