EyeWorld is the official news magazine of the American Society of Cataract & Refractive Surgery.
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November 2012 Device focus Rings, segments, and hooks: Inside the need for capsular tension devices by Michelle Dalton EyeWorld Contributing Writer genital issues, using a ring for up to 180 degrees "that doesn't have su- ture material attached to it or was intended to be sutured can work wonderfully," Dr. Condon said. "The biggest thing that happened was when the [Food and Drug Adminis- tration] approved the Ahmed capsular tension segment [CTS, Morcher, Stuttgart, Germany/FCI Ophthalmics, Pembroke, Mass.]. That completely changed the game for me." He may suture in a segment to further support the capsule, but he's used rings for up to 180 degrees of zonular loss in the presence of otherwise intact zonules, he said. "When it comes to progressive Dr. Miller implants a CTR Source: Source: Kevin Miller, M.D. What potential complica- tions are they preventing, pearls for inserting them, and when to remove or retain them Z onular weakness makes for complicated cataract sur- gery, but with the advent of capsule tension support devices—be they rings, seg- ments, or hooks—cataract surgeons are finding it a bit easier to manage. Incremental design modifications have increased the "customization" of the devices, experts say. Kevin M. Miller, M.D., Kolokotrones professor of clinical ophthalmology, Jules Stein Eye Institute, Los Angeles, was involved in the Ophtec CTR (Groningen, the Netherlands) study, and said "the most common indica- tion was diffuse zonular laxity of un- known etiology. We thought it was going to be pseudoexfoliation, but it wasn't." According to Garry P. Condon, M.D., chairman, Department of Ophthalmology, Allegheny General Hospital, Pittsburgh; and clinical as- sociate professor of ophthalmology, Drexel University College of Medi- cine, Philadelphia, in the broadest sense, these devices are used in three situations: in cases of zonular ab- sence in the presence of other viable zonules (trauma or congenital cases), in cases of inherent zonular disease where continual zonular integrity loss occurs, and in pseudoexfoliation cases. When the devices were first introduced, they were used only in inherent or iatrogenic zonular weakness, but more recently, surgeons have begun using them with toric and presbyopia-correcting lenses for better centration, said Bonnie An Henderson, M.D., partner, Ophthalmic Consultants of Boston. Capsule tension maintenance devices need to stabilize the capsule during and after surgery, said Priscilla Perry Arnold, M.D., in private practice, Eye Surgeons Asso- ciates, Bettendorf, Iowa. Hooks designed for maintaining support of the capsule are "slightly larger" than iris hooks and must be removed prior to the conclusion of surgery, Dr. Arnold said, while rings fill the capsule perimeter and are left in place; segments provide additional support and can be used with or without rings and may or may not be removed after surgery. When to use which? Segments can be "very useful and buttress the areas of weakness when securing and centering the lens," Dr. Henderson said. In trauma or con- disease—where patients have a pro- gressive subluxation of their crys- talline lenses—those cases demand a capsular tension support device that is sutured to the wall of the eye," Dr. Condon said. In cases of pseudoexfoliation, "don't shove a ring in there," Dr. Condon said. "You need to support the capsule as best as possible at the beginning of the case without creat- ing undue stress on the zonule." He'll typically use capsule hook de- vices like from MicroSurgical Tech- nology (MST, Redmond, Wash.) and the Mackool system (FCI) in those cases. Dr. Miller uses rings in cases where 1 or 2 clock hours of weak- ness exist and hooks in cases of severe trauma where 3 to 6 clock hours are gone. "We usually use segments in combination with a regular CTR," he said, adding the combination is equivalent to a Cionni ring (Morcher/FCI) but without the diffi- cult implantation. "I'll use the com- Cataract continued from page 51 in diabetic patients with clinically significant macular edema and cataract. Retina. 2011;31(4):755-758. 7. Szaflik JP, Szaflik J. Prevention of vision loss after cataract surgery in diabetic macular edema with intravitreal bevacizumab: a pilot study. Retina. 2010;30(8):1328-1329. 8. Ahmadabadi HF, Mohammadi M, Beheshtnejad H, Mirshahi A. Effect of intravit- real triamcinolone acetonide injection on cen- tral macular thickness in diabetic patients having phacoemulsification. J Cataract Refract Surg. 2010;36(6):917-922. 9. Hill, Warren. www.doctor-hill.com/iol- main/silicone.htm. Accessed September 30, 2012. Editors' note: Dr. Oetting is professor of clinical ophthalmology, and director, ophthalmology residency program, University of Iowa, Iowa City. He has no financial interests related to this article. Contact information Oetting: thomas-oetting@uiowa.edu bination in cases where the zonule is gone—not loose, just gone." Dr. Arnold suggests using hooks first to maintain the integrity and position during phaco, and then inserting rings or segments toward the end of the surgery. "Rings also help retard capsular contraction," she said. "If a patient is at high risk for capsular contraction, I wouldn't hesitate to use a ring." Pearls for implantation Ken Rosenthal, M.D., has been widely credited with the caveat to insert a CTR as late in the case as possible but as early as needed. The difficulty with implantation, how- ever, is that once inserted, removing the cortex "is very difficult," Dr. Miller said. "But if the whole equa- tor of the capsule starts collapsing in or you start getting vitreous, then you waited too long." Inserting the ring "can damage the zonules even further," Dr. Condon said. "You're placing stress on the zonules, so placing them where zonules are missing is fine, but in a case of pseudoexfoliation, for instance, inserting the ring further compromises the zonules." Dr. Henderson created a modified ring to address the cortex removal issue—her ring includes "indentations to allow space between the capsule and the CTR for gentler removal of the residual cortical material." When surgeons are concerned about "undue traction against a weak capsule," Dr. Arnold suggests the suture can be passed through the leading loop, and "with your second hand the suture can be used as a continued on page 54 EW CATARACT 53