Eyeworld

EW CATARACT 70 February 2018 by Stefanie Petrou Binder, MD, EyeWorld Contributing Writer Presentation spotlight A novel iris expanding ring easily engages the anterior and posterior surfaces of the iris by means of alternating tabs along the length of the ring I ris expanders are commonly and gratefully implemented by cataract surgeons in eyes with small pupils. Enlarging the pu- pil makes cataract surgery safer and easier. It allows the surgeon im- proved visualization that facilitates anterior capsulorhexis performance, lens removal, and IOL implantation, without damaging ocular tissues through space constraints. Eye sur- geons keep a number of iris expand- ers in stock to suit the operation at hand and their surgical preference. One of the problems with iris expanders is getting them into place. Adding to the cataract sur- geon's well stocked instrumentari- um is a novel iris expansion device that is not only easy to place along the iris edge and remove from the eye after surgery but may also offer the best solution for damaged irises or irises with colobomata, condi- tions that could preclude the use of other expanders. In a presentation at the 2017 ASCRS•ASOA Sympo- sium & Congress, the ring's develop- er, Sergio Canabrava, MD, Centro Oftalmologico de Minas Gerais, Belo Horizonte, Brazil, explained that the Canabrava ring (AJL Ophthalmic, Araba, Spain) is an all-purpose iris expander. Canabrava ring "This is an innovative device that provides great help in small pupil cases, damaged irises, and colobo- ma. I have successfully used the Canabrava ring in eyes with 90 degrees of iris trauma and lens sub- luxation, which other devices could not do," Dr. Canabrava said. The Canabrava ring consists of an incomplete PMMA ring forma- tion with ultralight tab-like parts oriented either up or down along the ring. The up oriented parts fit over the pupil edge and the down oriented parts fit under the pupil edge, allowing the device to engage the iris like a wave. The indents of the ring do not align with each other in the superior and inferior regions, resulting in a small vertical length. The two ends of the ring have hooks to aid in device stability and manipulation. The Canabrava ring creates a 6.3 mm diameter pu- pillary aperture and has a thickness of 0.4 mm, minimizing endothelial contact. It disengages the iris using a single motion, held by a simple forceps. The device is inserted halfway into the anterior chamber using a forceps and, with the help of a Sinskey hook, rotated and put into Expanding the iris needs to be safe and easy continued on page 72 place along the iris. "The ring stays stable during surgery and through- out phacoemulsification," Dr. Canabrava said. "In a case I man- aged that involved a damaged iris, the Canabrava ring provided the stability necessary to cut the capsu- lar bag with a scissor and even place capsular tension segments. This iris expansion device did not disengage during phaco or IOL implantation. Removal is simple, since it is only 0.4 mm wide." In a government run consec- utive case series of 30 eyes in 29 patients who underwent cataract surgery using the Canabrava ring, Dr. Canabrava could implement the ring in all patients to stabilize the iris and achieve a 6.3 mm wide pupil. 1 To date, he has used the iris expander in at least 60 eyes, only two of which could not be implant- ed due to fibers within the iris. "Other rings on the market vary in thickness between 0.7 and 0.9 mm. This ring is thinner because of the alternating parts that engage the iris," Dr. Canabrava said. "It is also the first expander ring to be pro- duced with ultralight parts. The ring gives the perfect stiffness all the way around the iris to stabilize even a damaged iris during surgery and re- main stable through all the manip- ulations that occur during surgery. The iris does not dislodge, thanks to the special design of the device." optic is stable, and more important- ly the haptics are resilient (made of PVDF), which despite manipulation, do not kink but rather stay in a configuration that is amendable to scleral fixation. I have learned a few other things from the challenges I have had with this technique. For instance, it is important that the sclerostomies are 180 degrees apart for central lens placement. We use a scleral ruler that allows you to make your marks evenly 180 degrees apart. I try to grab the haptic during insertion to remain outside of the eye. Once externalized, I try not to lose it. I make smaller sclerostomies, 23-gauge, then like to make sure that the microforceps slide through cleanly, before IOL implantation. When the IOL is inserted I cre- ate a scleral tunnel using a 25- or 27-gauge needle, right next to my sclerostomies, then I place the hap- tics into the scleral tunnel. Finally, I suture down the haptics for extra support so that there is no slippage back into the eye." Dr. Garg warned of bleb forma- tion, patients with scarring or previ- ous surgery, thin scleras, insufficient vitrectomies, and a large white-to- white, in which he would try to orient the haptics vertically. "Scleral tunnel fixation solves long-term suture degradation issues," he said. "The tissue glue seals the sclerostomies and provides short-term stability while scleral compression of the haptics creates permanent stability and is the key to the success of this technique. This fixation technique is a nice option for the right patient, but you cer- tainly have to individualize it to the patient and the situation." EW References 1. McAllister AS, et al. Visual outcomes and complications of scleral-fixated posterior chamber intraocular lenses. J Cataract Refract Surg. 2011;37:1263–9. 2. Kumar DA, et al. Complications and visual outcomes after glued foldable intraocular lens implantation in eyes with inade- quate capsules. J Cataract Refract Surg. 2013;39:1211–8. Editors' note: Dr. Garg has no financial interests related to his comments. Contact information Garg: gargs@uci.edu Cataract continued from page 69 " I have successfully used the Canabrava ring in eyes with 90 degrees of iris trauma and lens subluxation, which other devices could not do. " —Sergio Canabrava, MD

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