June 2018

CATARACT

Device focus
Reports of early use of Zepto


by Rich Daly EyeWorld Contributing Writer


The Zepto capsulotomy system, including handpiece and control console

Zepto’s manufacturing protocols aim to avoid nitinol capsulotomy rings with imperfections (top left) and produce only rings that enable 360-degree even energy delivery (top right); a Zepto capsulotomy with 360-degree, slightly rolled-up, and strong capsulotomy edge from cadaver eye (bottom left); surgical photo showing Zepto capsulotomy after lens phaco and cleanup (bottom right)
Source: David Sretavan, MD

Surgeons share pearls and surgical results for the capsulotomy device approved for the U.S. market in 2017

The latest device approved to create capsulotomies has provided cataract surgeons with a helpful option and some unexpected benefits.
The Zepto capsulotomy system (Mynosys Cellular Devices, Fremont, California) uses a handpiece attached to a laptop-sized console to create a “phase transition” of water molecules trapped between the device and the capsule to create capsulotomies, said David Sretavan, MD, co-founder of Mynosys Cellular Devices.
“What’s unique is that the tissue cutting action is delivered by a ring, so the capsulotomy happens 360 degrees at the same time,” Dr. Sretavan said. “Surgeons using Zepto have identified its unique capsulotomy action as beneficial in high pressure cataract situations where it relieves pressure and completes the entire capsulotomy at the same instant.”
The device involves three steps: creating suction so the cutting element is opposed tightly against the capsule surface; directing the energy to the capsule ring; and reversing suction at the end of the procedure to float the Zepto tip off the capsule.
The U.S. Food and Drug Administration granted 510(k) clearance for the Zepto in June 2017.
Elizabeth Yeu, MD, assistant professor, Eastern Virginia Medical School, Norfolk, Virginia, has used the device for 3 months and found getting comfortable with it was relatively easy.
“I love having the ability to create a standardized, well-centered capsulotomy in the OR and saving the time that it takes me to create the same step in the laser room with femtosecond laser assistance,” Dr. Yeu said.
Dr. Yeu sees its ability to automate the capsulotomy as a boost to refractive outcomes.
David F. Chang, MD, clinical professor, University of California, San Francisco, has used the Zepto device since the 2016 FDA clinical trial and said the learning curve to master its nuances is about 10 cases.
Dr. Chang agreed that efficiency is one major advantage of the device. Surgeons merely use the disposable Zepto tip in lieu of capsule forceps in the normal surgical sequence.
“This means that you can employ Zepto after iris retractors have been inserted for a small IFIS pupil, for example,” Dr. Chang said.
Kevin Waltz, MD, president, Ophthalmic Research Consultants, Indianapolis, has used the device since 2016 and found it has provided more reliable capsulotomies than manual techniques.
“The advantage of that is there’s great centration of the optics with the capsulotomy so you don’t get lens tilt, decentration, or a lot of things that could be uncomfortable if you don’t have a perfect capsulotomy,” Dr. Waltz said.
Manual capsulotomies are frequently too small, off center, or irregular, which can affect lens positioning.
Dr. Waltz said the device has fit well within the clinical workflow, with it taking the same or less time as other approaches.
Another key component of the device is that it allows patients to interact with the surgeon during surgery by fixating on a surgical light, which allows centering the device and the capsulotomy on the visual axis.
Surgeons can use the resulting visual landmark during surgery to align the IOL within the capsulotomy.

Other advantages

Surgeons using the device have identified another, unintended benefit, Dr. Sretavan said.
In the last step where suction is reversed, ophthalmic viscosurgical device is reintroduced along with a little balanced salt solution and creates a subcapsular fluid wave. Surgeons have reported this helps hydrodissection and also seems to remove lens epithelial cells under the capsule that they otherwise need to remove using other methods.
“Zepto appears to be more than just a capsulotomy device; it appears to also help in other steps of surgery such as hydrodissection and cortical cleanup,” Dr. Sretavan said.
Dr. Chang’s research on the device has found the simultaneous use of suction seems to create a microscopic curling of the cut capsulotomy edge that imparts greater tear resistance.1
“Unlike with the femtosecond laser, there is no cutting or disturbance of the underlying cortex because only tissue in contact with the thin nitinol edge will be cut,” Dr. Chang said. “Therefore, hydrodissection and cortical removal are no different than with a manual capsulorhexis.”
The strength of the capsulotomy edge is important with more complicated cases. Dr. Chang’s and others’ research comparing Zepto to manual and femtosecond laser capsulotomy found it was consistently stronger in paired human cadaver eyes.2
“It is with large, brunescent cataracts that we exert the most surgical force on the capsular bag and capsulorhexis,” Dr. Chang said. “For example, with chopping we have to manually separate the two hemi-nuclei much further apart to fracture the posterior nuclear plate.”

Pearls identified

Surgeons have identified a variety of ways to improve the device’s performance.
“Initial experience has taught us the importance of retracting the push rod all the way back to its starting position before activating suction,” Dr. Chang said. “Otherwise, insufficient suction could create a skip area in the cut, and this was a part of my learning curve.”
Among the pearls Dr. Yeu has found to improve efficiency with the device is extending wounds from the 2.2 mm required to 2.3 mm, which eases ingress and egress of the Zepto device.
Dr. Waltz has found it unnecessary to use capsular dye once a surgeon becomes comfortable with Zepto.
“If you have a dense cataract and you are afraid of an anterior capsular rip, Zepto makes a precise 360 degree cut, so you release the pressure in a real way,” Dr. Waltz said. “You can also put the Zepto behind a small pupil, and you can get a good 5.2 mm capsulotomy behind the pupil.”

References

1. Chang DF, et al. Precision pulse capsulotomy: Preclinical safety and performance of a new capsulotomy technology. Ophthalmology. 2016;123:255–64.
2. 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.

Editors’ note: Dr. Sretavan, Dr. Chang, and Dr. Waltz have financial interests with Mynosys. Dr. Yeu has no financial interests related to her comments.

Contact information

Chang
: dceye@earthlink.net
Sretavan: sretavan@mynosys.com
Waltz: kwaltz56@gmail.com
Yeu: eyeu@vec2020.com

Reports of early use of Zepto Reports of early use of Zepto
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