CIONNI MODIFIED CAPSULAR TENSION RING

Robert J. Cionni, MD

In 1993, Drs. Legler and Witschel demonstrated the concept of the capsular tension ring (CTR) for stabilizing weakened zonules¹ (Figure 6-1). However, the idea of placing a circular ring into the capsular bag was first conceived by Drs. Nagamoto, Bissen-Miyajima, Hara, and coauthors.^2–5 This concept sparked a new era of managing complex cases with compromised zonules. However, patients suffering from significant zonular damage, manifested as marked phacodonesis or lens displacement, did not achieve sufficient dampening of intraocular lens (IOL) movement or recentration of the capsular bag-IOL complex with a standard CTR. In 1998, Cionni and Osher introduced the modified CTR (M-CTR or Cionni ring).⁶ This modification allowed for scleral fixation of the M-CTR without violating the capsular bag integrity to achieve capsular bag centration and stabilization in these more challenging cases. The M-CTR has now been used for patients with severe zonular compromise for more than 20 years. The history of its use and its modifications since inception will be reviewed in this chapter.

There are several models of the M-CTR. Type 1G has become the most popular because it is more flexible and thus easier to insert into the capsular bag (Figure 6-2). Scleral fixation with an M-CTR should be used when there is significant lens decentration to the extent that a standard CTR will not achieve adequate IOL centration. In general, this would include eyes with more than 3 to 4 clock hours of zonular dehiscence. However, the M-CTR can secure the capsular bag-IOL complex in cases of generalized zonulopathy with significant phacodonesis. With extensive zonular loss, using 2 scleral fixation points for the capsular bag should be considered. Options would be to use an M-CTR model with 2 fixation hooks (Type 2L) or to combine a single-hook M-CTR model with an Ahmed capsular tension segment (Figure 6-3). Dr. Boris Malyugin further modified the Cionni M-CTR to allow for implantation with an injector device⁷ (Figure 6-4).

Over the past 2 decades much has been learned about managing compromised zonules with an M-CTR. Initially, 10-0 polypropylene was used to suture the M-CTR to the scleral wall. However, it has been shown that over time, the polypropylene material may weaken and break, resulting in late subluxation of the capsular bag-IOL complex. Therefore, most surgeons now fixate the M-CTR with either 9-0 polypropylene (which will last longer but may still break over time) or Gore-Tex (WL Gore & Associates), which, lacking US Food and Drug Administration approval for intraocular use, must be used off-label. In cases of late polypropylene suture rupture, the M-CTR can be resutured with a mattress-style suture technique. Instead of trying to feed suture back through the fixation hook eyelet, the 2 needles are passed directly through the fibrosed capsular bag equator so that they ensnare the intracapsular ring in the appropriate location.

Numerous publications have documented the benefits of an M-CTR. Kim et al reported on a series of 19 pediatric eyes with ectopia lentis implanted with a Cionni ring or a combination of a CTR with a capsular tension segment. They concluded these techniques and devices to be a safe and effective for visual rehabilitation in pediatric ectopia lentis.⁸ Vasavada et al reported a prospective evaluation of 41 eyes with significant lens subluxation and concluded that implantation of a Cionni M-CTR with an IOL placed in the capsular bag appears to be a safe option in eyes with subluxated cataract.⁹ Drs. Do, Holz, and Cionni reported on the use of the Cionni ring in 41 eyes with subluxated lenses and astigmatism.10 They concluded that use of a Cionni ring in combination with implantation of a toric IOL was safe and effective in achieving a well-centered and stable IOL as well as improving uncorrected vision.

Management of zonular compromise can be very difficult, and although the management principles are similar, each case may present unique challenges. For example, some eyes with large areas of zonular weakness or loss are often easier to manage than other eyes with lesser degrees of zonulopathy. Additional factors besides the degree of zonular loss that affect the ease of surgery are:

• Severity of lens subluxation
  
• Any capsular bag deformity
  
• Patient age
  
• Cataract density
  
• Severity of phacodonesis

Cases where compromised zonules presented at a young age often demonstrate a misshapen capsular bag equator. Typically, this means that the unaffected zonules are much stronger than the compromised zonules, which can simplify surgery. The very dense cataract with generalized zonular weakness and marked phacodonesis in an older patient is often the most difficult case. Vitreous prolapse becomes more likely, and temporary use of capsular tension hooks or an Ahmed capsular tension segment may be necessary. If vitreous is found in the anterior chamber at any time during the procedure, it should be managed appropriately prior to proceeding with other intraocular maneuvers. Management may be as simple as pushing the vitreous back behind the capsular bag equator with an ophthalmic viscosurgical device (OVD) or might involve a pars plana vitrectomy.

Although the M-CTR can provide excellent long-term support and centration for an IOL in the capsular bag, occasionally the surgeon will find a situation where the capsular bag is just too loose to be salvaged. Other times, a torn anterior or posterior capsule precludes using an M-CTR. In these situations, the surgeon must be prepared to use alternative methods for IOL fixation following cataract removal. IOL fixation in the absence of sufficient zonular support can be accomplished with an anterior chamber IOL,11,12 suture fixation to the posterior iris surface¹³ or to the scleral wall,¹⁴ or nonsutured IOL fixation.¹⁵ Recently, Dr. Shin Yamane and coauthors introduced a method to fix the IOL to the scleral wall without sutures or glue.¹⁶ This technique is gaining in popularity due to its simplicity. Although IOL stability beyond 1 year has not yet been reported, this technique seems likely to provide good centration and long-term support.

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