September 2019

CATARACT

Yes Connect
New instrumentation for cataract surgery


by Liz Hillman EyeWorld Senior Staff Writer


The Zepto handpiece has a collapsible capsulotomy tip whose main component is a low profile, transparent silicone suction cup that houses a thin-walled nitinol capsulotomy ring.
Source: Russell Swan, MD


Adjusting an RxSight lens
Source: Bennett Walton, MD

This month’s YES Connect column focuses on new technologies in cataract surgery. In training, everything is new at first, but residents and fellows have the advantage of working with an experienced surgeon to guide them as they learn. Once in practice, though, there is both a time commitment to learning a new technique as well as a financial commitment in purchasing the technology. This month’s column explores the advantages and disadvantages of three new promising tools in cataract surgery that young surgeons may consider incorporating into their practices.

—Julie Schallhorn, MD, YES Connect
Co-editor

 

There are a number of new technologies making their mark in cataract surgery. Among them are Zepto (Mynosys), miLOOP (Carl Zeiss Meditec), and the Light Adjustable Lens (RxSight). Kevin Waltz, MD, Susan MacDonald, MD, and Bennett Walton, MD, offered their insights on these technologies.

Automating the capsulotomy

Creating a continuous curvilinear capsulorhexis manually is one of the most fundamental aspects of cataract surgery training, but there are a number of technologies that are automating this part of the procedure. The femtosecond laser is one example, but a more recently approved device with a smaller footprint is Zepto (FDA approved in 2017), which consists of a collapsible nitinol ring, a silicone suction cup, and an energy source that heats the nitinol ring and water molecules that are trapped in
the suction cup, creating the capsulotomy. CAPSULaser (Excel-Lens) is another automated capsulotomy device, but it is not yet approved by the U.S. FDA.
Dr. Waltz has been working with Zepto since 2015, initially as the principal investigator for the device’s first in-human trials in El Salvador. While the main purpose of Zepto is to create consistently sized, perfectly round, and reproducible capsulotomies centered on the visual axis, Dr. Waltz said the device provides a number of advantages beyond its original intent.
One that’s been documented in peer-reviewed literature is improved capsule strength. As Dr. Waltz said and as scanning electron micrographs show, Zepto creates a slight upturn
in the capsular edge at the cut. Capsule edge tear strength from capsulotomies created with Zepto, femto, and manually have been compared, and Zepto-created were found significantly more resistant to tearing.1
Dr. Waltz said there is early, unconfirmed, signals suggesting Zepto decreases the burden of epithelial cells remaining in the eye after surgery. He said long-term monitoring of patients in El Salvador, where you would expect to see a higher rate of PCO, show a low rate of PCO with Zepto. Dr. Waltz hypothesized that the vacuum release of the capsulotomy helps the surgeon do a thorough and effective hydrodissection that appears to “change the biology of the healing.”
Compared to the femtosecond laser, Zepto has advantages in price and footprint. Cortex removal, Dr. Waltz said, is easier with Zepto- created capsulotomies, while it’s harder with femtosecond laser-created capsulotomies. Advantages of the laser systems, Dr. Waltz noted, are that some are able to match the visual axis to markers on the capsule, and they can make astigmatic cuts.
But the femtosecond laser and Zepto are not mutually exclusive, Dr. Waltz said, noting that some surgeons who offer femto laser-assisted cataract surgery have found Zepto to be an attractive alternative upgrade for patients who cannot or do not wish to spend what FLACS would cost.
Dr. Waltz said he is currently transitioning his main practice from El Salvador back to Indianapolis where he will use Zepto when he thinks it’s beneficial to the patient. While some surgeons use mechanical devices like Zepto in every case to get a perfectly centered and sized capsulotomy to reduce higher order aberrations and lead to more predictable outcomes, Dr. Waltz said others will use it in more complicated cases, such as those with zonulopathy or white cataracts.
Dr. Waltz provided a couple of pearls for Zepto success. First, he said you have to withdraw the pushrod of the device fully before applying vacuum; if you don’t, the vacuum is inadequate and you could get an incomplete cut. Second, give the vacuum time to develop. The vacuum creates bubbles inside of the system, and these bubbles move while the vacuum is building. The vacuum is being pulled through 8 feet of tubing and it takes a few seconds to fully develop the vacuum inside of the eye. Dr. Waltz said once the bubbles in the eye stop moving, the vacuum is fully engaged.

Cataract fragmentation

Since its FDA approval in 2017, miLOOP has been making waves for its ability to fragment even the densest cataracts manually. Consisting of a nitinol filament that is deployed by a surgeon-held handpiece and pulled through the cataract like a cheese wire, as Dr. MacDonald put it, surgeons have been sharing success stories of using miLOOP in soft cataracts and brunescent cataracts.
Dr. MacDonald, who mainly performs surgery outside the U.S. in developing countries where the cataracts are generally harder and manual small incision surgery is used, said the miLOOP learning curve for phaco surgeons is simple.
“The device is self-explanatory. As a phaco surgeon, I’ve always thought of my second instrument as something that I manipulate, and one piece of advice I can give to someone who is using the miLOOP is to not try to manipulate the nucleus with the miLOOP. If you follow the directions, it will do exactly what it’s supposed to do,” she said.
Now performing SICS regularly, Dr. MacDonald said miLOOP has made it possible to deliver the cataract fragments through small incisions.
In the U.S., Dr. MacDonald thinks that surgeons will find it makes them more efficient. How it is incorporated into their practice will be individualized, though she does think the technology makes surgeons better. Internationally, she said “it’s going to give phaco a run for its money.” It is a skillset that is easy to transfer and makes for safer surgery in some of these settings, Dr. MacDonald said.

Nailing IOL power postop

Missing a refractive target used to mean spectacles, contact lenses, laser vision correction, or an IOL exchange for the patient. Newer technologies, like the Light Adjustable Lens (LAL), which is FDA approved, and Perfect Lens, which is not yet FDA approved, are giving surgeons the ability to lock in IOL powers (sphere, cylinder, and multifocality) postoperatively.
“Since IOLs have historically been manufactured in pre-set powers, all patients have been subject to the variability of preoperatively guessing the effective lens position and how the cornea will heal,” Dr. Walton said. “Even modern IOL power estimation formulas—we say estimation instead of calculation at our practice to reinforce the truth that there is variability and not every eye will hit the target—have about a 20–30% rate of missing the outcome by 0.5 D in most practices. The Light Adjustable Lens allows us to place the IOL power that seems best, then adjust and lock in the power with a non-invasive light treatment postoperatively.”
Dr. Walton said the learning curve for this technology is easy. Surgeons who don’t have experience with implanting silicone IOLs might find that they unfold quicker than single-piece acrylics, and the treatments with a proprietary light source to adjust the lens postop are “intuitive,” according to Dr. Walton. The biggest barrier to this technology, Dr. Walton said, is a familiar one to refractive cataract surgeons.
“Many or even most surgeons are uncomfortable discussing patient pay technologies, even when they might offer the patient a more precise or more visually freeing result,” he said.
Dr. Walton, however, doesn’t find this discussion difficult. He said he tells patients that this technology allows them to fine-tune their vision without the cataract in the way, but Medicare and insurance do not cover this technology.
Dr. Waltz was a principle investigator of the U.S. FDA PMA trial for the LAL from 2012. That LAL trial was a toric trial and Dr. Waltz said it produced the best uncorrected visual results in a clinical trial he has ever observed. “The LAL is likely to have a profound effect on IOL choice and visual outcomes in the years to come,” he said.
One possible drawback of the technology is that patients have to wear UV-blocking glasses until the final treatment is locked in, which can be for about 3 weeks postop. As such, Dr. Walton thinks patients will want their second cataract surgery performed shortly after the first to reduce total UV protection time and allow both eyes to be adjusted together.

About the doctors

Susan MacDonald, MD
Associate professor
Tufts University School
of Medicine
Boston

Bennett Walton, MD
Slade & Baker Vision
Houston

Kevin Waltz, MD
Partner, Whitson Vision
President, Ophthalmic Research Consultants
Indianapolis

Reference

1. Thompson VM, et al. Comparison of manual, femtosecond laser, and precision pulse capsulotomy edge tear strength in paired human cadaver eyes. Ophthalmology. 2016;123:265–74. 

Relevant financial interests

MacDonald
: Carl Zeiss Meditec, Perfect Lens
Walton: RxSight, Carl Zeiss Meditec
Waltz: Mynosys

Contact information

MacDonald: susanmacdonaldeyecorps@gmail.com
Walton: drwalton@visiontexas.com
Waltz: kwaltz56@gmail.com

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