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AAOpt 2023: Embracing technology to combat HOA


Clark Chang, OD, MSA, MSC, FAAO, shares highlights from his 2023 AAOpt presentation, which he co-presented with Christine Sindt, OD, FAAO.

Clark Chang, OD, MSA, MSC, FAAO, sat down with Optometry Times®' editor Kassi Jackson to share highlights from his 2023 American Academy of Optometry meeting presentation, "CL-06: New Wave Thinking on Wavefront Guided Contact Lenses," which he co-presented with Christine Sindt, OD, FAAO, in New Orleans.

Editor's note: This transcript has been edited for clarity.

Kassi Jackson:

Hi everyone, I'm joined today by Dr. Clark Chang, who is here to talk about his presentation, which he gave during the 2023 American Academy of Optometry meeting in New Orleans. Welcome, Dr. Chang.

Clark Chang, OD, MSA, MSC, FAAO:

Hi, Kassi; hi, everybody.


Will you please just give us a quick overview of key takeaways and what you presented during the academy?


I was invited, along with my co-speaker Christine Sindt, OD, FAAO, to talk about higher order aberration in terms of contact lens application, which is obviously very, very relevant to many of us in our practice.

We've been wanting this for a long time, and are very excited that we're slowly making advancements in this field to help with that [for] our patients. The lecture went very well, I do want to give a very quick shout out to my collaborators who I have worked with on preparing my information, such as Nick Brown, as well as Dr. Jenny Wong. And obviously we look through literatures with my co-speaker, myself, Dr. Christine Sindt.

Some of the highlights that, in my mind, we presented are—and I think many of you have heard me discuss this technology before and some of the recent advancements, so let's sort of skip the contact lens backgrounds and the contact lens fitting techniques.

In terms of the the fitting specifics, let's talk about—I think what's more important is: How do we select these patients and who are people who I we think can benefit from this technology? At least those who are, I think, easier for us to help throughout this learning curve, as we're going through.

So number one, we discussed the fact that obviously you need a stable lens. If you don't have a stable contact lens on the eye, any rotational movement, translational movement is going to also change the amount of higher order aberration that may be induced or can be corrected.

And so and that is the reason why we're favoring scleral lenses, I think right now, is [it is] more stable on the eye compared to a lot of different lenses—not to excluding that other lenses could work in the future. Currently, I'm utilizing scleral lenses to build this technology.

That's number one; and I do want to say as little as possibly rotating 3 to 5 degrees can even be detrimental to this technology, or at least to sort of unable to reap the maximum benefits. So that's very important.

Number two, if we want something to be stable, whether you worked on decentering the optics and everything is perfect, if the patient is still progressing, that's not really gonna give them maximum benefit.

So, we showed a case about dry eye in terms of tear film changes over the scleral lens can even induce higher order aberration changes, in that the patient is experiencing. So control anything that may be fluctuating or progressing, including keratoconus; you need to stabilize the cornea first, before utilizing this tool. [You] need to manage those condition sthat can be progressive. So that's also, I think, very important.

Once the patient's ready, you fit the lens, you found a stable lens platform to use in terms of a scleral lens, how do you determine the patient can really benefit again, from this technology, because you're going to spend a couple of extra visits or a little more chair time with the patient.

I personally found that anytime that—obviously pending your aberrometer, units are a little different, so you may have to take that into account and talk to [the] manufacture. But anybody 0.4 to 0.6 or above, in terms of their total RMS seem to —more often than not—report that they can notice the improvement. Not to say that anybody with way more or way less than RMS won't benefit.

One of the studies that Dr. Sindt presented is that she took a group of patients and broke them down in terms of severity of their condition and found that everybody improved, but those who reported the most amount of improvement as sort of in the moderate stage where they don't have extremely high or extremely low RMS, [and] that it could be have something to do with neuro adaptations. Those with a lot of RMS, as you're trying to correct them, they're higher order aberration and their experience or their symptom, they have to kind of get used to it because they already have filtered out some of the effects of higher order aberration that they've experienced from the past many, many years.

So then that takes us down to, I think, one of the last notable for me, which is then neural adaptation. Just because you got [the] patient down to a very ideal range of higher order aberration, or RMS, that you are now measuring to be much, much more reduced. But the patient is not yet appreciating that improved visual experience, because we'd also need to discuss with patients about the fact that there'll be some neuro adaptation period that they may have to work through, pending where they were coming from, how much RMS or higher order aberration they were experiencing.

So hopefully that helps you to be able to select patients properly. And if you want to learn more, hopefully I'll see you at one of the lectures that Dr. Sindt and myself give in the future.


Absolutely. So just a couple of follow up questions. Why is this so important for optometrists to know and address in their own practice?


I think number one, we've always known from literature that there are patients who, despite best fitting contact lenses—typically it's contact lenses, these irregular cornea patients, and a lot of them that we take care of in our clinic. And we always, as doctors, want to give them the best outcome.

We know that a lot of patients, despite best fitting lenses, still report having poor quality of life or quality of vision, and we don't quite know what to do with them. And we've been telling them that there's really nothing much we can do. And I think as doctors, we're frustrated with that answer that we give our patients. And that's why this is such an important breakthrough. We've been working at it for years and hadn't really found like the perfect lens platform to work with. And right now, [it's] looking like scleral lenses would at least give us that opening. And I think that extra tool in our toolbox is going to go on and serve many, many patients. And that's why it's important for us.


Wonderful. So on the patient side of things, what does this technology mean for patient care?


I mean, this technology is, again, as it expands, there are going to be many frontiers that I think we will come to and will kind of check one by one in the future because it could also have surgical implications—this technology had been utilized in refractive surgery, for example. And also, you know, some of it has started to kind of enter the IOL world, which is post-cataract. So you can imagine that this then possibly is a lifelong tool that patients can use.

And whether it's in contact lenses, or if they're not irregular cornea or not keratoconus patients, maybe this would affect their refractive surgery outcome. And regardless, we know that we're all going to need cataract surgery, if we live long enough. And you may still you still want your best vision at that time. So knowing what recipe went into a contact lens. And this is just one of the examples knowing the higher order aberration correction recipe that went into your contact lens that gave you best vision can kind of guide future surgery that you may need, or come back to combine with a contact lens after a certain medical procedure.

So I think for the patient's perspective, this opens up a lot more doors for them in terms of their journey to their management, whether they're regular cornea and athletes who need super X-ray, human vision, or irregular cornea patients who needs to enjoy their life and have regained their autonomy, to be able to live out their best quality of life and with the best quality of vision.


Wonderful. Any closing thoughts?


I just think that everybody should come to the lecture that Dr. Sindt and I give, but embrace technology. I think patients look to us for answers [and] they want to know that we are delivering the latest and the greatest—not that the latest is always the best, we obviously need to exercise our own medical judgment. But we know that there's a group of patients who are underserved at this moment, and they wish for better visual freedom. And again, it may be required combination.

One of the message that I hope everybody heard loud and clear is that it doesn't matter how great your technology is, if the patient is still progressing, whether it's their dry eye, whether it's keratoconus, it's going to affect the longevity of the treatment that we prescribe to our patients.

So make sure that we embrace technology, be early adaptors so that we can help the many patients who may be under our current care, and also have new patients that we could help. But most of all, to know that we as a profession are at the tip of the medical technology utilization. I think that means a lot to our patients.


Wonderful. We appreciate your insights. Dr. Chang, thank you for joining us today.


Thank you for having me. Thanks, everybody.

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