Eyeworld

AUG 2012

EyeWorld is the official news magazine of the American Society of Cataract & Refractive Surgery.

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August 2012 EyeWorld journal club Los Angeles County-University of Southern California residents review: "Cataract surgery with trabecular micro-bypass stent implantation in patients with mild-to-moderate open-angle glaucoma and cataract: Two-year follow-up" by Ramya Swamy, M.D., Jesse Berry, M.D., Alex Huang, M.D., and Luis Vazquez, M.D. Cataract surgery with trabecular micro-bypass stent implantation in patients with mild-to-moderate open-angle glaucoma and cataract: 2-year follow-up E. Randy Craven, M.D., L. Jay Katz, M.D., Jeffrey M. Wells, Pharm.D., Jane Ellen Giamporcaro, B.S., for the iStent Study Group J Cataract Refract Surg (August) 2012; 38:1339-1345 Funded by Glaukos Corp., Laguna Hills, Calif. Peter A. Quiros, M.D., Doheny Eye Institute, University of Southern California, Los Angeles This month I asked the USC residents to review this paper reporting 2-year follow-up for the micro-trabecular bypass stent. In light of the recent FDA approval of the iStent, both the paper and the review couldn't be more timely. –David F. Chang, M.D., chief medical editor I n this article sponsored by Glaukos (Laguna Hills, Calif.) and published in the August issue of the Journal of Cataract & Refractive Surgery, "Cataract surgery with trabecular micro-bypass Hole continued from page 62 chamber shallowing, as this may cause undue anterior prolapse of vitreous and/or expansion of the po- tential capsular violation. The use of continuous irrigation can be quite helpful in this situation, especially for less experienced surgeons who may not be as comfortable with foot control of the phaco pedal. Also, always instill OVD into the anterior chamber before coming in and out of the eye to maintain a deep ante- rior chamber, thus preventing ante- rior prolapse of the dreaded vitreous. The point that a true capsular hole is identified can occur at any time but may unfortunately become very obvious rather quickly if disrup- tion of the hole leads to splitting across the posterior capsule and instability of the remaining intra- capsular nuclear fragments. If this occurs, stop and refill the posterior space with the dispersive OVD. Try to use the viscoelastic to float the fragments forward. The size and number of the remaining fragments will determine how the surgery should proceed. If possible, lift the remaining fragments into the ante- rior chamber and finish emulsifying the pieces in the AC. But if the pieces are fairly large and/or dense, one may need to extend the temporal wound to a larger incision (~5-6 mm) using a crescent blade, functionally converting to an extra- capsular manual delivery of the re- maining pieces. If nuclear pieces do fall posteriorly, absolutely leave the pieces alone. After a thorough anterior vitrec- tomy is performed, try to place an intraocular lens implant into the eye, so long as the view allows for an IOL to be safely placed, even if there may be some retained lens frag- ments within the vitreous cavity. If the capsulorhexis is round, centered, and a decent size, I would opt for a three-piece sulcus IOL with optic capture. In some instances, the capsular hole will remain just that, a perfect round hole for the remainder of the case. Repeatedly use the dispersive OVD to prevent any anterior pro- lapse of the vitreous, as this would then necessitate an anterior vitrec- tomy to be performed, which will commonly clip the capsule and cause extension of the violated cap- sule. If the capsular rent remains only a round hole, without any vit- reous prolapse, a more experienced surgeon may carefully place a single- piece IOL within the bag itself. But a three-piece sulcus IOL with optic capture will do just as well post-op. In regard to how to prevent being a repeat offender of this situa- tion, there are two tips that can be helpful. First, grooving should be performed slowly, smoothly, and at an even depth across the length of the groove. With any lens, try to gauge and utilize only the phaco power necessary to emulsify the nucleus while grooving. Do not be overly aggressive (i.e., flooring the foot pedal) as this can lead to lack of control and grooving through the nucleus, especially with softer ones. On the other hand, use the neces- sary energy to emulsify a denser nucleus, as not doing so can cause occlusion and vacuum to build. Pressing deeper into the foot pedal and/or increasing the energy level will prevent unnecessary occlusion of the tip, thus preventing any "microsurges" and their consequences from occurring. EW Editors' note: Dr. Banta, Naseri, and Yeu have no financial interests related to this article. Contact information: Banta: jamesbanta@hotmail.com Naseri: ayman.naseri@va.gov Yeu: yeu@bcm.edu Purpose: To assess the long-term safety and efficacy of a single trabecular micro-bypass stent with concomitant cataract surgery versus cataract surgery alone for mild to moderate open-angle glaucoma. Setting: Twenty-nine investigational sites, U.S. Design: Prospective, randomized, controlled, multicenter clinical trial. Methods: Eyes with mild to moderate glaucoma with an unmedicated intraocular pressure (IOP) of 22 mm Hg or higher and 36 mm Hg or lower were randomly assigned to have cataract surgery with iStent trabecular micro-bypass stent implantation (stent group) or cataract surgery alone (control group). Patients were followed for 24 months post-op. Results: The incidence of adverse events was low in both groups through 24 months of follow-up. At 24 months, the proportion of patients with an IOP of 21 mm Hg or lower without ocular hypotensive medications was significantly higher in the stent group than the control group (P=.036). Overall, the mean IOP was stable between 12 months and 24 months (17.0 mm Hg±2.8 [SD] and 17.1±2.9 mm Hg, respectively) in the stent group but increased (17.0±3.1 mm Hg to 17.8±3.3 mm Hg, respectively) in the control group. Ocular hypoten- sive medication was statistically significantly lower in the stent group at 12 months; it was also lower at 24 months, although the difference was no longer statistically significant. Conclusions: Patients with combined single trabecular micro-bypass stent and cataract surgery had significantly better IOP control on no medication through 24 months than patients having cataract surgery alone. Both groups had a similar favorable long-term safety profile. EW RESIDENTS 63 stent implantation in patients with mild-to-moderate open-angle glau- coma and cataract: Two-year follow- up," the authors presented evidence for improved IOP control and de- creased dependence on IOP-lowering medications as well as long-term safety and efficacy of the iStent device (Glaukos) combined with continued on page 64

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