November 2019

CATARACT

Research Highlights
Capsulotomy creation: Searching for perfection


by Rich Daly EyeWorld Contributing Writer


Measurement is key to obtain an ideal capsulorhexis. This image demonstrates forceps which have built-in measurement capabilities for that purpose.

The capsulorhexis overlaps the edge of the optic for 360 degrees but is large enough so that it does not cover a significant part of the optic.
Source(all): Uday Devgan, MD

Specific patient situations and evolving views on technology are informing surgeons’ approaches to capsulotomy creation, a procedure that can be performed manually or with various devices.

Manual, femto, and Zepto

Uday Devgan, MD, performs manual capsulorhexis, Zepto (Mynosys Cellular Devices) capsulotomies, and femtosecond laser capsulotomies, with his approach depending on the type of patient and their anatomy.
“A routine case may not benefit from a Zepto or femto-laser capsulotomy as much as an intumescent, white cataract case,” Dr. Devgan explained. “Even then, there is no guarantee of success and you can have an incomplete laser-made capsulorhexis in some cases.”
Surgeon skill is more influential on high-quality clinical outcomes, than use of technology like a femtosecond laser, Dr. Devgan said. For example, forceps can be used to create a 5-mm capsulorhexis, even if the pupil only dilates to 4 mm by passing the forceps tips under the iris—an approach is not possible with a femtosecond laser.
In contrast, novice surgeons or those who have difficulty making an excellent capsulorhexis may improve their results by using a femtosecond laser or Zepto device, Dr. Devgan said.
Larry Patterson, MD, performed femtosecond capsulotomies for 4 years and then about 2.5 years ago switched back to creating a manual capsulorhexis. Despite the expectation that femto-laser capsulotomies would increase accuracy and precision, Dr. Patterson found they weren’t as strong as those created manually. His return to manual was reinforced by studies repeatedly finding femtosecond-created capsulotomies were more likely to tear under pressure.
“It wasn’t just the studies showing that, we were obviously getting more anterior capsular tears with the laser. I rarely have an anterior capsular tear now that we’ve switched back to 100% manual,” Dr. Patterson said.
He also found femtosecond laser-created capsulotomies did not always end up exactly where he thought they would.
“I can do a manual capsulotomy and I can put it exactly where I want it to be,” Dr. Patterson said.
The additional cost and time added to the procedure were cited by the doctors as a disadvantage for using femtosecond lasers to create capsulotomies. But among newer devices that cost less than femtosecond laser systems is the Zepto capsulotomy system. Zepto 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.
Dr. Patterson said one advantage of this device is that it is performed on the operating table, which keeps operating time short. In addition, some reports indicate that it results in a stronger capsule edge.
“There may be some other advantages, but for right now those all cost extra money and you can’t bill for the extra cost, so for the near future, we’ll be sticking with manual capsulotomies,” Dr. Patterson said.

Creating the ideal capsulotomy

For all planar, fixed-position IOLs, Dr. Devgan aims for a capsulorhexis that overlaps the edge of the optic 360 degrees while not covering a significant part of the optic. That means for the common IOL optic size of 6 mm, his ideal capsulorhexis is about 5–5.5 mm in diameter.
“When we center this on the patient’s visual axis, we will be able to hold the IOL optic securely, thereby giving better predictability in the effective lens position used for IOL calculations, and better long-term stability and visual performance,” Dr. Devgan said.
His approach applies to monofocal, multifocal, trifocal, extended depth of focus, and toric IOLs.
Dr. Patterson strives for a capsulorhexis of 5.5 mm for the common 6-mm lens.
“As the capsule opening gets smaller you are less likely to catch the edge of the optic on the edge of the anterior capsular rim and that’s a good thing, but if you get too far below 5 mm—and with the laser you could make these exactly the size you wanted—we learned that it started getting progressively more difficult to operate due to such a small opening.”
For extremely dense cataracts, Dr. Patterson creates a 6.5–7-mm capsulorhexis.
“With really rock hard lenses, you need more room to maneuver, and with these very large openings there is no overlap at all,” Dr. Patterson said.

Lens positioning impact

The capsulorhexis plays a role in determining the final resting place of the optic—known as the effective lens position­—when accounting for IOL calculations, Dr. Devgan said.
“If most of the optic is overlapped by the capsulorhexis, even if it is less than the full 360 degrees, the effective lens position will likely be stable,” Dr. Patterson said. “[If] you are looking at the white-to-white and the center of the limbus and the iris, you will see it centered in such a way that when you insert the implant [it] will be in its final resting place and it’s going to overlap.”

Pearls for a manual capsulorhexis


Pearls for a good capsulorhexis, Dr. Patterson said, include filling the anterior chamber with viscoelastic to the point of pushing the lens back and flattening the anterior lens surface.
Instead of starting a capsulorhexis with a tear using forceps, Dr. Patterson uses a bent needle to minimize viscoelastic loss.
“It’s just easy and quick and cheap, and you just put it in underneath the capsule and just keep going. And you’ve just got to take your time and don’t let it extend too far out, but if you do, then there are techniques to pull it back in,” Dr. Patterson said.
For Dr. Devgan, ensuring precise measurement for an ideal capsulorhexis means using forceps, which have these measurements built in.
“This allows for exact planning for every case and it just takes a second or two,” Dr. Devgan said. “Many forceps come with these tips and you can even add these marks to your existing forceps.”

About the doctors

Uday Devgan, MD
Private Practice, Devgan Eye Surgery
Clinical professor of ophthalmology
Jules Stein Eye Institute
Chief of ophthalmology, Olive View UCLA Medical Center
Los Angeles

Larry Patterson, MD
Medical director
Eye Centers of Tennessee
Crossville, Tennessee

Relevant financial interests

Devgan: CataractCoach.com, Mynosys
Patterson: None

Contact information

Devgan
: devgan@gmail.com
Patterson: larryp@ecotn.com

Capsulotomy creation: Searching for perfection Capsulotomy creation: Searching for perfection
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