July 2018

CATARACT

YES connect
Managing cases of loose zonules with hooks, rings, and segments


by Liz Hillman EyeWorld Senior Staff Writer

Loose zonule cases can be intimidating for surgeons of all ages. Thankfully our toolbox of techniques and instruments related to this surgical challenge continues to expand. In my experience, a zonular case that goes well is tremendously rewarding and can significantly boost surgeon confidence. Undoubtedly, preparation is paramount for success. This includes practicing surgical techniques in the wet lab and working in an operating room where the staff and surgical supply inventory are prepared to handle a complex case.
In this month’s “YES connect” column, Brandon Ayres, MD, Lisa Arbisser, MD, and Julie Schallhorn, MD, share invaluable insights into managing weak zonules. I would add that recently I have found the miLOOP (Iantech, Reno, Nevada) to be an excellent instrument that can be used to disassemble very dense, loose lenses without inducing zonular stress because of its unique mechanism of action. Anything that can help avoid exacerbation of already weak zonules can be a tremendous asset in handling these difficult cases.

Zachary Zavodni, MD,
YES connect co-editor


Experts discuss the why, when, and how of capsular tension hooks, rings, and segments


High-magnification photo of a capsular retracting hook. The rounded tip allows for safe placement in the capsular bag.

Watch a video of Dr. Arbisser’s technique on EWAR


Placement of a CTR in a patient with a traumatic cataract and zonulysis. In this case, a lens positioning hook is being used to help safely place the CTR in the capsular bag.

Subluxation of the crystalline lens in a patient with homocystinuria

Placement of a CTS in a patient with Marfan syndrome. A Gore-Tex suture is placed through the eyelet in the CTS and externalized through sclerotomies. The suture and eyelet are positioned above the capsular bag while the ring segment is located in the capsular bag. The knot is tied on the scleral surface allowing proper positioning of the capsular bag and IOL. In this case an IOL and CTR have already been placed in the capsular bag.

Three capsular hooks are placed through limbal wounds holding a lens with severe zonulopathy in place, allowing safe removal. In this case the patient had idiopathic zonulopathy. Notice how the hook is placed through the capsulorhexis with the tip of the hook at the equator of the lens.
Source (all): Brandon Ayres, MD

 

As a referral-based cataract and cornea surgeon, Brandon Ayres, MD, cornea service, Wills Eye Hospital, and instructor, Jefferson Medical College, Thomas Jefferson University, Philadelphia, said zonular laxity is the number one reason cataract patients are sent to him. While he might be well-versed in handling these cases now, there was a time when he, like residents and those early in professional practice, didn’t have any experience in the effective management of loose zonules, using capsular hooks, capsular tension rings (CTRs), and capsular tension segments (CTSs).
“If this is something that you have a passion for, you’ve got to say ‘yes’ at some point, and see what happens,” Dr. Ayres said. “With proper planning and backup if you need it from a more senior surgeon, these case are doable, and I don’t think people should shy away from them as long as they have a game plan.”
Dr. Ayres, Lisa Arbisser, MD, adjunct professor, Department of Ophthalmology and Visual Sciences, University of Utah School of Medicine, Salt Lake City, and Julie Schallhorn, MD, assistant professor, Department of Ophthalmology, University of California, San Francisco, shared their thoughts on what that game plan might look like, from what to look for in the preoperative exam through the intraoperative nuances of using the variety of devices that might be needed to safely complete these cases.

Preoperative planning

With a thorough history and preoperative exam, being surprised by loose zonules in the operating room should be a rare, uncommon occurrence, Dr. Arbisser said.
Drs. Arbisser, Ayres, and Schallhorn all had similar advice on what to look for. On the history, complications with the first eye, if it has already been done, could be a red flag, as well as a history of trauma, prior ocular surgeries (including vitrectomy and glaucoma), and congenital cataract. A history of Marfan syndrome or an eye that is very myopic refractively without a lot of nuclear sclerosis and without the axial length and measurements that would be expected with high myopia could be an indicator of zonular problems as well, Dr. Arbisser said.
On examination, physicians should look for signs of phacodonesis. Dr. Schallhorn and Dr. Ayres said they’ll tap or rock the eye and have the patient look left to right and straight again to see if there is any motion of the lens.
Signs of pseudoexfoliation, pseudoexfoliative material on the pupil border, or a pupil that doesn’t dilate well should “raise your antenna for potential problems during surgery,” Dr. Ayres said. Traumatic iridodialysis or iris defect could be a sign of weak zonules in that area as well, he added.
Dr. Arbisser said every OR should have materials available for the management of loose zonules, including capsule hooks, CTRs, and CTSs, and the relevant tools the surgeon would need to employ those devices. In addition, she advised planning one’s surgical schedule with these cases in mind, scheduling more complicated cases for later in the day. Dr. Arbisser noted that these cases seem to have more inflammation postoperatively, so she would advise a preoperative NSAID and a longer course of NSAIDs.

Intraoperative signs of loose zonules

There might be cases where you don’t determine there are weak zonules preoperatively, but there are several intraoperative clues to look for.
“For very weakened or absent zonules, the first indication is usually with the capsulorhexis,” Dr. Schallhorn said. “When you don’t have the radial tension from intact zonules to pull against, the rhexis will behave strangely or start shooting out. When I see a large area of zonular instability during the rhexis, I generally will put in capsular support hooks right from the get-go.
“During phaco, I also will look for how the nucleus is behaving. If the bag/nuclear complex is very mobile with chopping or if the entire nucleus is decentered, this is another sign you have zonular instability,” Dr. Schallhorn continued. “However, the most common time that I see zonular issues is after the nucleus has been removed and you can see the bag folding in during irrigation and aspiration. … After cortical removal, a decentered capsulorhexis is a good clue there is zonular laxity. The capsule will pull away from the area of laxity and toward the area of intact zonules. Significant ovalization of the capsule after IOL placement is also a sign of diffuse zonular weakness.”
Dr. Arbisser said when the lens won’t rotate after a good hydrodissection, “that’s a big clue you have an issue.” At this point Dr. Arbisser said she’ll avoid the usual one-handed rotation using the chopper and the imbedded phaco tip during vertical chop to loosen the nucleus from the cortical or epinuclear shell. In the worst cases the nucleus can be chopped in situ without rotation. Sculpting is never a good idea as it can stress subincisional zonules, Dr. Arbisser said. When necessary, for those who prefer divide and conquer, sculpting should be done with an appropriately high ultrasound setting to avoid pushing the nucleus, she said. Dr. Schallhorn tells her residents it’s important to keep the nucleus central and stable as you chop to avoid zonular stress. 

Capsular tension hooks

Dr. Schallhorn said she is ready to place capsule tension hooks, and specifically mentioned Mackool hooks (FCI Ophthalmics, Pembroke, Massachusetts), after she’s seen instability upon creation of the capsulorhexis when there is still nuclear material in the bag. She said the Mackool hooks can be cumbersome to manipulate inside the eye, but they provide “excellent capsular support.” She’ll make her incisions posterior to the limbus using a Grieshaber stab knife (Alcon, Fort Worth, Texas), although a 25-gauge needle can be used.
Dr. Ayres said he’s “a strong proponent of as soon as you know, start doing something to stabilize that lens.” There are times when he’ll start placing hooks before completing the capsulorhexis.
“You need to make sure that you’re placing the capsule retractors in the meridian or in the clock hours of the zonular dehiscence and if it’s a global dehiscence … you’ll need three to four hooks evenly spaced throughout the limbus,” he said. “You need to make sure the incisions for those hooks don’t get in the way of the incisions you need for cataract surgery.”
Dr. Arbisser mentioned the “hammerhead,” or T-shaped Yamaguchi capsular tension hooks, or the Microsurgical Technology (MST, Redmond, Washington) hooks because they evenly distribute the pressure on the capsulorhexis edge and the latter effectively puts a floppy posterior capsule on stretch. The Chang-modified MST hooks are best as they have a terminal closed loop and don’t allow accidental threading by the CTR, she said.

Capsular tension rings

There’s an oft quoted saying from Kenneth Rosenthal, MD, about placing a CTR as early as necessary but as late as possible, and while many still subscribe to this sentiment, others think it’s antiquated information in light of modern devices.
Dr. Ayres said that a CTR might be challenging to put in if you haven’t removed enough of the nucleus and it could make cortical removal difficult, so he’ll try to get as much cortex out before placing a CTR.
“But if there is so much zonulopathy that I think I’m in danger of causing progressive zonulopathy by not supporting the lens, I will put a capsular tension ring in. It depends on the case. If I had to err on the side of earlier or later, I would say earlier is going to be safer,” he said.
Dr. Schallhorn said if she is at the cortical removal stage with 3 clock hours or less of zonular dialysis she’ll put a CTR in, preferring the Henderson CTR (FCI Ophthalmics), which she said makes for easier cortical removal.
In addition to making cortical removal difficult, Dr. Arbisser has a couple of other sticking points with early CTR placement. Putting it in early has been shown in the Miyake-Apple view to cause zonular stress even when viscodissection is used to make space between the capsule and lens material.
“What the CTR did when placed early was reduce the likelihood during the last throws of phaco for the floppy posterior capsule to come up and get dinged. The capsule expansion hooks from MST … eliminate, in my opinion, any logic to placing a CTR prior to removal of nucleus,” Dr. Arbisser said. “Even if you only had hooks that support the anterior capsule, there are other steps you can take to prevent the posterior capsule from flopping upward, and you should protect it with the second hand instrument or dispersive OVD once exposed anyway. The CTR can give a false sense of security for lens centration as well.”
Sometimes it is necessary to place a CTR before the last bit of cortex removal, Dr. Arbisser said, in which case the remaining cortex should be viscodissected and dragged to the opening of the CTR without exerting centripetal pressure on the zonules.
Both Dr. Arbisser and Dr. Ayres said they prefer CTR placement with an inserter, whether it’s manually loaded or preloaded. Both also emphasized the importance of filling the bag with OVD. Dr. Ayres said he will use a suture-assist in some cases or a second instrument, such as a Kuglen hook (MST) or Lester lens manipulator (MST), to let the CTR land softly as it comes in contact with the capsular bag. Dr. Arbisser said her preference when zonules are severely abnormal is to place 10.0 nylon through the leading eyelet of the CTR, which she then loads into an inserter and uses forceps outside the eye to hold the two strings acting as a tether; if you’re happy with placement of the CTR, you cut the strings. Dr. Schallhorn said if she is concerned about bag integrity, she will also place a suture through the trailing loop and free-pass it into the eye.
In terms of size, Dr. Arbisser said the larger CTRs can be stiffer and more difficult to manipulate. Dr. Ayres and Dr. Schallhorn said they don’t view the size of a CTR as critical. If too large of a CTR is used, Dr. Ayres said it will just overlap itself, which he doesn’t think will cause a problem. As a general rule, Dr. Schallhorn uses a 10–11 mm CTR for small eyes, a 12 mm CTR for medium eyes, and a 13 mm for large eyes.

Capsular tension segments

Dr. Schallhorn uses an Ahmed segment (FCI Ophthalmics) if there are more than 3 clock hours of zonular dialysis. Though some surgeons will put their Gore-Tex suture knot in a scleral groove, Dr. Schallhorn said she finds this difficult and thinks it might put too much tension on the rhexis; thus, she prefers to create a 3-mm, square scleral flap hinged at the limbus. Before making sclerotomies with a 25-gauge MVR blade, she makes sure there is enough viscoelastic over the capsular bag, below the iris, to avoid spearing the bag. After threading Gore-Tex through the segment loop, Dr. Schallhorn passes the thread to 25-gauge MaxGrip (Alcon) retinal forceps through the sclerotomy in a handshake technique, repeating the process for the second end of Gore- Tex. Afterward, she fills the bag with OVD and inserts the segment, positioning it with a Sinskey hook. Dr. Schallhorn finds the correct tension with three throws total in the Gore-Tex and careful tightening.
“I want to see the capsulorhexis centered but with minimal distortion where the eyelet overlaps the edge of the rhexis,” she explained. “Once I have the tension correct, I put in a second throw, making sure not to tighten it further. I then put in a third throw and cut the suture, leaving small tails. After that, I glue down the flap using Tisseel [Baxter Healthcare, Deerfield, Illinois], then glue the [conjunctiva] back into place.”
Dr. Ayres said if he needs to stabilize the capsular bag, he’ll place a capsular segment after a CTR, thinking that if you need to use a capsular tension segment, most of the time you should be putting in a ring as well for expansion of the bag and even distribution of equatorial forces. Dr. Ayres marks on the limbus where he wants to pull the lens toward, makes an X that extends beyond that mark, and goes 2 mm posterior to the limbus to make sclerotomies 3–4 mm apart. Similar to Dr. Schallhorn, Dr. Ayres uses a handshake technique with forceps through the sclerotomy to pass the two ends of the Gore-Tex suture from the main incision. Once the segment is placed, Dr. Ayres ties a slipknot on the scleral surface to apply tension until the IOL in the bag looks centered.
Though she admitted she doesn’t have a lot of experience with capsular tension segments, Dr. Arbisser said they are “a wonderful invention.” She mostly uses Cionni-modified CTRs, which provide both the effect of a CTR and scleral fixation. She prefers an ab externo approach with a 26-gauge hollow bore needle into which is docked the straightened 8-0 Gore-Tex needle. This allows the knot to be tied over the 26-gauge perforation and pushed intrascleral through the perforation with a Sinskey hook. She specifically likes the AssiAnchor (Hanita Lenses, Hanita, Israel) developed by Ehud Assia, MD, which currently has the CE marking, because of its broad pressure on the capsulorhexis edge that doesn’t tent the circular rhexis opening like the Ahmed segment.

When to tackle and when to pass

Even as an experienced surgeon, Dr. Arbisser said there has been an occasional case where she would give the patient the option for a referral to someone with even more experience if they’d prefer. If it’s a one-eyed or otherwise high-risk patient in the fellow eye, Dr. Arbisser said it would be reasonable to refer a patient to a colleague who does extreme surgery every day.
But taking on the learning curve of these techniques is something all surgeons have to go through, Dr. Arbisser continued. Dr. Ayres said gaining experience with all of these devices for the management of loose zonules is important because they will come up in your practice. When a case of known zonular dehiscence is coming up, he suggested talking over your plan A, B, and C with a more experienced surgeon ahead of time to gain tips and confidence. Dr. Arbisser recommended practicing some of these techniques on the eye models that are available or in a skills transfer wet lab.
“At some point, everyone who is going to be doing cataract surgery is going to have to deal with this. … Everybody should know the ABCs of how to deal with loose zonules, even if it wasn’t in your plan or wasn’t intended. Knowing what tools, tricks, and instruments are out there to help you is important,” Dr. Ayres said.

Editors’ note: Dr. Ayres has financial interests with Alcon and MST. Dr. Schallhorn and Dr. Arbisser have no financial interests related to their comments.

Contact information

Arbisser
: drlisa@arbisser.com
Ayres: brandonayres@me.com
Schallhorn: jschallhorn@gmail.com

Interested in getting hands-on experience? The Combined Ophthalmic Symposium on August 24–26 in Austin, Texas, and YES Advanced Cataract Training on September 15–16 in San Francisco have advanced phaco stations that will include hooks and rings, MIGS, limbal relaxing incisions, lens folding, and more.

Managing cases of loose zonules with hooks, rings, and segments Managing cases of loose zonules with hooks, rings, and segments
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