EyeWorld is the official news magazine of the American Society of Cataract & Refractive Surgery.
Issue link: https://digital.eyeworld.org/i/104833
14 EW NEWS & OPINION January 2013 Tools & techniques Tips on CTR implantation by Bonnie An Henderson, M.D. The capsular tension ring (CTR) is perhaps one of the simplest but most useful adjunctive devices in ophthalmic surgery. Whether used at the beginning of a case or midway through creation of a large zonular dialysis, this device has the power of turning a potential disaster into a successful outcome. The CTR is now available as preloaded rings that can be inserted either clockwise or counterclockwise allowing for implantation that can transpire with the least amount of zonular stress. In this month's column, Bonnie An Henderson, M.D., gives her tips and pearls for successful loading and implantation of CTRs. I particularly like her tip for placing viscoelastic on the CTR while it is still in the package to prevent "tiddlywinking" of the ring onto the floor. Richard Hoffman, M.D., Tools & techniques editor C apsular tension rings (CTR) are C-shaped devices made of polymethylmethacrylate used during cataract surgery to stabilize the lens capsule. CTRs were first introduced by Hara et al1 in 1991. In the 15 years since, several modifications have been made. These rings are used to increase the stability of the lens capsule during and after lens extraction and IOL implantation. CTRs can be utilized in many conditions including zonulolysis from trauma or previous surgery, mature cataracts, high myopia, and pseudoexfoliation. CTRs may also be useful in disorders that influence the ciliary zonule such as Marfan's syndrome, Marchesani syndrome, scleroderma, homocystinuria, spherophakia, porphyria, and hyperlysinemia. Furthermore, a CTR can be helpful in cases where exact centration of the IOL is needed after cataract surgery to achieve a satisfactory visual result such as with multifocal and toric IOLs. Timing Watch this video on your smartphone or iPad using your QR code reader. (Scanner available for free at your app store.) The timing of the implantation of the CTRs varies depending on the individual clinical case. The ring should be placed to provide the best stability of the lens capsule diaphragm. In some cases, the CTR should be placed immediately after the capsulorhexis has been made. In other cases, it is not needed until cortical removal or immediately before IOL insertion. However, early ring implantation has been found to increase capsular torque and displacement, and removing cortical material after placing the CTR may be difficult and tedious.2 Therefore, if placing a CTR early in the surgery, a modified CTR with indentations can be useful for easier cortex removal. Technique CTRs can be inserted manually or by injector systems. The modification with suturing eyelets such as the Cionni or Ahmed segments must be inserted manually. Before inserting any CTR, the capsular bag should be inflated with a dispersive viscoelastic solution. The dispersive viscoelastics, such as chondroitin sulfate, will maintain the capsular bag expansion while the CTR is being manipulated. The cohesive viscoelastics made from sodium hyaluronate can be inadvertently extruded during the implantation. To load the CTR into the injector, place a few drops of viscoelastic into the CTR in the package. By doing so, the viscoelastic will hold the CTR in place in the package while engaging the eyelet into the hook of the injector. This will prevent the CTR from bouncing around and falling out of the package. If possible, the insertion of the CTR should begin in the area of the most zonular dialysis and injected clockwise. The greatest amount of stress on the capsular bag is at the initial introduction of the CTR. Hence if the location of the initial implantation is at the weakest area, the CTR is being pushed toward the weakness and relaxing the remaining zonules. If the CTR is implanted 180 degrees away from the area of weakness, the force of the implanted CTR pulls from the weakness and causes the remaining zonules to be strained. Often the greatest difficulty of implanting any CTR is the final placement of the trailing end. With manual and injector implantation, the final end must be carefully placed in the capsular bag. The difficulty of this step originates from the inability to release the final trailing eyelet from the hook inside the injector system or the hook of the manipulating instrument. I recommend using a second instrument in the sideport incision to push off the trailing end of the CTR and to assist in the placement of the end into the capsular bag. The decision of when to use a CTR or a sutured CTR varies depending on the amount of zonular weakness. If the dialysis is greater than five clock hours, the lens is brunescent, the pupil dilates poorly, and the integrity of the remaining zonules is compromised, then phacoemulsification of the lens—even with the use of capsular hooks and CTRs—may not be the best approach. In these instances, it may be safer to remove the lens through a large incision manual extracapsular approach or even with a planned pars plana lensectomy-vitrectomy. When selecting a surgical approach in the presence of a zonular dialysis, one must consider other ocular variables such as pupil size, corneal endothelial health, lens density, and the surgeon's familiarity with using capsular hooks and CTRs. Conclusion CTRs have proven to be useful devices for cataract surgery since their introduction in 1991. During the 15 years since, many modifications have been made to improve upon the original. Although CTRs can be useful in stabilizing the eye for successful completion of surgery, the implantation of these rings should be carefully planned and executed properly. EW References 1. Hara T, Hara T, Yamada Y. "Equator ring" for maintenance of the completely circular contour of the capsular bag equator after cataract removal. Ophthalmic Surg 1991;22:358-359. 2. Ahmed II, Cionni RJ, Kranemann C, Crandall AS. Optimal timing of capsular tension ring implantation: Miyake-Apple video analysis. J Cataract Refract Surg 2005;31:1809-13. Editors' note: Dr. Henderson is assistant clinical professor of ophthalmology, Harvard Medical School, Boston. Dr. Henderson has no financial interests related to this article. Contact information Henderson: bahenderson@eyeboston.com Taking continued from page 11 adding a CTR, and finally if it rotated a third time, reverse optic capture with a laser iridotomy could be considered as a final option. EW Editors' note: Drs. Arbisser, Jones, Lane, and Wong have no financial interests related to this article. Dr. Safran has financial interests with Bausch + Lomb. Contact information Arbisser: drlisa@arbisser.com Horn: jeff.horn@bestvisionforlife.com Jones: jasonjonesmd@mac.com Lane: sslane@AssociatedEyeCare.com Safran: safran12@comcast.net Wong: mwong2020@gmail.com