Using CTRs in practice/ September 2023 EYEWORLD
Using CTRs in practice
Cataract: Complicated cases
September 2023 EYEWORLD
by Ellen Stodola
Editorial Co-Director
A capsular tension ring (CTR) can be a useful tool for ophthalmologists to have on hand during surgery. Two physicians discussed the available products, when the best time is to use them, and methods for good placement.
John Hart Jr., MD, said there are three CTR products that he routinely uses: a standard CTR, a Cionni CTR, and the Ahmed capsular tension segment.
“I use a CTR in approximately 10% of my cataract cases,” Dr. Hart said. “Patients with zonular abnormalities are commonly referred to me by other ophthalmologists. I think that most ophthalmologists don’t use them as frequently as I do.”
When a CTR is properly positioned in the capsular bag, it distributes support from areas with intact zonules to areas with weak or missing zonules, Dr. Hart said. The CTR also keeps the equator of the capsular bag expanded in areas where zonules are missing. “This is important because if zonules are missing and the cataract is being removed, the equator of the bag will collapse inward, increasing the likelihood of damaging the capsular bag with the phacoemulsification or I/A tip,” he said. “If the equator of the bag collapses inward, there is also a much greater chance of vitreous loss and subsequent vitreous-retinal complications.”
Dr. Hart said that the CTR should be placed “as late as possible but as early as you need it,” adding that this is a direct quote from Kenneth Rosenthal, MD. “In the FDA trials for the standard Morcher CTR, we placed the CTR after hydrodissection,” he said. “I commonly place the CTR after cortical cleanup. That way I don’t trap cortex between the CTR and the capsule.”
Yuri McKee, MD, noted that there are several different types, sizes, and manufacturers of CTRs. “Most designs are a simple, smooth ‘C’ ring with eyelets at the terminal ends,” he said. “Sizing is typically done using the white-to-white measurement as a surrogate for capsular diameter.” He said the Henderson CTR has undulations on the ring designed to allow for the removal of cortex from behind the CTR. More specialized CTRs, such as the Ahmed segment or Cionni ring, are designed to allow for scleral fixation of the device in the case of severe zonular compromise, he said.
Dr. McKee said he uses a CTR if focal zonular compromise is noted, either prior to or during surgery. “This is around 5% of my cases, but as a referral practice, I probably see more cataracts with zonular deficiency than average,” he said.
A basic CTR is designed to redistribute the strength of healthy zonules to areas of zonular weakness. “Up to 90 degrees of continuous zonular weakness can be remedied with a basic CTR,” he said. “If 90–180 degrees of zonular damage are present, one or two Ahmed segments secured to the sclera via the ciliary sulcus would be appropriate. For more than 180 degrees of zonular compromise, a Cionni ring with two eyelets for scleral fixation can be used.”
Dr. McKee noted that it may sometimes be obvious ahead of surgery that a CTR or support segment will be needed. In other cases, the zonular weakness may not be apparent until during surgery. “The ideal time to place the CTR is after cortical cleanup and prior to the placement of the IOL in the capsule,” he said. “In some cases, the cortical cleanup may cause worsening zonular weakness. In these cases, the CTR can be placed prior to cortical cleanup to stabilize the capsule, but this could make cortical cleanup more difficult.”
Source (all): John Hart Jr., MD
When to use a CTR
Dr. McKee said that certain genetic conditions, such as Marfan syndrome, Weill-Marchesani syndrome, or Ehlers-Danlos syndrome, are associated with zonular abnormalities. “Support segments may be required during cataract surgery for these cases,” he said.
Trauma is likely the most common cause of focal zonular damage, he said. Pseudoexfoliation syndrome is associated with global zonular weakness and late dislocation of an IOL-capsule complex. The placement of a CTR in pseudoexfoliation does not necessarily increase support for the capsule or prevent late dislocation of the IOL, Dr. McKee said, but it may help to reduce capsule phimosis, and it does offer a stable substrate for fixation of a subluxated IOL-capsule complex that can occur many years after the original cataract surgery.
In cases where a single-piece toric acrylic IOL is used, Dr. McKee said some surgeons think that a CTR can help to reduce the postoperative rotation of the toric IOL. The Henderson CTR may be especially useful due to the undulating design. Highly myopic eyes with a deep anterior chamber and/or a large capsule may be better candidates for using a CTR to help prevent rotation of a toric IOL, he said.
Dr. Hart said that he uses a standard CTR in all his pseudoexfoliation syndrome cataract cases, all cases with documented blunt trauma, cases with zonular dialyses, and cases where he visualizes the equator of the capsular bag (indicates stretched zonules).
“I commonly use CTRs in patients with an axial length greater than 26 mm. I use them routinely in patients with an axial length greater than 26 mm where I am placing a toric IOL. If I have to reposition a toric IOL because it has rotated to the wrong axis, I will routinely use a CTR. I place the CTR at the first sign of zonular instability,” he said.
Methods for best placement
CTRs can be placed with an inserter or manually, Dr. Hart said. He added that there are reusable inserters, and there are preloaded disposable inserters. The reusable inserters are made to insert the CTR in a clockwise manner. The disposable inserters can insert the CTR in a clockwise or counterclockwise manner.
Dr. Hart added that the direction of insertion can be important, depending on where the zonular weakness is localized in relation to the main incision. “If the CTR encounters resistance during insertion, the surgeon should remove it and attempt insertion in the opposite direction,” he said. “There are other ways to insert a CTR with an inserter, including a Sinskey-guided insertion or a suture-guided insertion. These techniques help guide the leading tip of the CTR around the equator of the capsular bag.”
Alternatively, the CTR can be inserted manually with the assistance of a Sinskey hook in the distal eyelet and a Kuglen hook guiding the CTR into the bag, Dr. Hart said, adding that he most often uses a disposable inserter.
Several methods for placement of the CTR have been described in the literature, Dr. McKee said. “I currently use the preloaded CTRs from Bausch + Lomb, as they are high quality, easy to insert, and come preloaded in a sterile disposable injector,” he said. “These come in right- and left-handed orientation, but by simply inverting the injector, the orientation can be reversed. With the preloaded CTR, I insert the tip of the injector into the capsular opening and slowly inject the CTR.” The terminal trailing eyelet will be engaged by a small rod/hook in the injector advancing the CTR. Once this hook is fully advanced, the CTR can be disengaged from the injector with a second instrument or often by simply elevating the hook and having the CTR fall into the capsule.
Dr. McKee noted that it is important that the capsule is intact for proper placement of a CTR. “A CTR should not be placed in the ciliary sulcus,” he said. “The capsule should be intact for CTR placement to prevent loss of the device into the vitreous cavity.” He also mentioned that the ‘S’ sign when placing a CTR is an important warning that should alert the surgeon to stop and attempt a different manner of CTR placement, noting an article from the Journal of Cataract & Refractive Surgery that discussed this.1
Weakened and stretched zonules
Source (all): John Hart Jr., MD
Additional considerations
Dr. McKee cautioned that when using a CTR, you should avoid sulcus placement or attempted placement in a torn/broken capsule.
Other problems can accompany zonular damage, Dr. McKee said, such as vitreous prolapse, iris damage, peripheral retinal tears, and cystoid macular edema. “A CTR is often used in a complex case, and a high index of suspicion for other problems should be present.”
Dr. Hart said that as a general rule for three or less clock hours of zonular dialysis, you can use a standard CTR. If the dialysis is larger than this, a scleral-fixated CTR, like a Cionni ring, is indicated. “There are times where you place a standard CTR but you realize that there is insufficient zonular support,” he said. “In these cases, you can combine a suture-fixated Ahmed capsular tension segment with a standard CTR. I use a sclerally fixated Cionni CTR in all Marfan syndrome patients.”
Dr. Hart said he thinks surgeons should practice using CTRs in pseudoexfoliation syndrome patients when the placement is relatively easy. “That way when they encounter more complex zonular abnormalities, they are more comfortable using CTRs,” he said. “It is important to dedicate extra OR time when you are operating on someone with zonular abnormalities. These cases typically take longer than routine cases. There is no shame in referring these patients out to surgeons who routinely handle these cases.”
About the physicians
John Hart Jr., MD
Associates in Ophthalmology
Farmington Hills, Michigan
Yuri McKee, MD
East Valley Ophthalmology
Mesa, Arizona
Reference
- Page TP, et al. ‘S’ means stop! Critical examination of capsular tension ring movements with Miyake-Apple video analysis. J Cataract Refract Surg. 2021;47:379–384.
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