EyeWorld Asia-Pacific June 2011 Issue

June 2011 17 EW FEATURE A Baerveldt drainage device and Ahmed drainage device implanted inferiorly, at varying degrees of magnification Source: Leon W. Herndon, MD at 1 week (P<0.001) and 1 month (P<0.001). Survival rates after 1 year were 80.5% with the Ahmed and 80% with the Baerveldt (P=0.839). There was no difference in complication rates (P=0.699) or improved visual acuity, maintained visual acuity, and loss of visual acuity between the two groups. There also was no significant difference in the intraocular pressure control, success rate, visual outcomes, and complication rates between the phaco/Ahmed and the phaco/Baerveldt groups at 1 year after surgery. However, the phaco/ Baerveldt group required a greater number of post-op interventions (P=0.022). In response to the rising use in tube shunts, the Trabeculectomy Versus Tube study was conducted to compare complications and outcomes between patients. Patients who had previously undergone failed trabeculectomy or cataract surgery and required surgery for IOP control were randomized to undergo either trabeculectomy with mitomycin-C or implantation of a nonrestrictive Baerveldt implant. The 5-year study enrolled patients from 1999 to 2003. It included 212 patients between ages 18 and 85 who had an IOP between 18 mmHg and 40 mmHg, and who had previous trabeculectomy, cataract explantation with IOL implantation, or both. After 1 year, non-valved tube shunt surgery was found to be more likely to maintain IOP control and avoid persistent hypotony or reoperation for glaucoma than trabeculectomy with MMC. Three-year outcome data from the TVT study was reported in Current Opinion in Ophthalmology. According to the abstract, the intermediate-term results of the multicenter, randomized clinical trial supports the use of tube shunts, even beyond refractory glaucoma. “Tube-shunt surgery is an appropriate surgical option in patients who have undergone prior cataract and/or unsuccessful filtering surgery,” the study found. Trabeculectomy rates in the TVT study were twice as high as for tubes, with 30% of trabs failing within 3 years, compared to 15% of tubes. Failure was defined as IOP being too high (>21 mmHg) or too low (<5 mmHg), the need for reoperation, or loss of light perception vision. Post-op, wound leaks and dysesthesia were more common in the trabeculectomy group, while post-op diplopia was more common in the tube group. Dr. Sarkisian said he removes the cataract before moving on to the shunt implantation in the pars plana. “It’s a very rewarding opportunity when a patient has had a previous vitrectomy and there might be scarring of the conjunctiva,” he explained about the positioning of the device. “Then the tube has no chance of coming in contact with the cornea. “The refractive result is not going to be as impressive initially as it would be when doing the cataract surgery alone,” he continued. “IOP control is paramount. You don’t want to have inflammation from cataract surgery.” EW References 1. Gedde SJ, Schiffman JC, Feuer WJ, et al. The Tube Versus Trabeculectomy Study: Design and baseline characteristics of study patients. Am J Ophthalmol. 2005;140:275– 287. 2.Gedde SJ, Schiffman JC, Feuer WJ, et al. Treatment outcomes in the Tube Versus Trabeculectomy Study after one year of follow-up. Am J Ophthalmol. 2007;143:9–22. 3.Minckler DS, Francis BA, Hodapp EA, et al. Aqueous shunts in glaucoma: A report by the American Academy of Ophthalmology. Ophthalmology 2008;115:1089–1098. 4.Wilson MR, Mendis U, Smith SD, et al. Ahmed glaucoma valve implant vs. trabeculectomy in the surgical treatment of glaucoma: A randomized clinical trial. Am J Ophthalmol. 2000;130:267–273. 5. Tsai JC, Johnson CC, Dietrich MS. The Ahmed shunt versus the Baerveldt shunt for refractory glaucoma: A single surgeon comparison of outcome. Ophthalmology 2003;110: 1814–1821. Editors’ note: Dr. Ahmed has financial interests with AMO. Dr. Samuelson has financial interests with AMO, AcuMems (Menlo Park, Calif., USA), Alcon, Allergan (Irvine, Calif., USA), AqueSys (Irvine, Calif., USA), Endo Optiks (Little Silver, NJ, USA), Glaukos, iScience (Menlo Park, Calif., USA), Ivantis (Irvine, Calif., USA), Pfizer (New York, NY, USA), QLT (Menlo Park, Calif., USA), and Santen (Napa, Calif., USA). Dr. Sarkisian has no financial interests related to his comments. Contact information Ahmed: 416-625 3937, ike.ahmed@utoronto.ca Samuelson: 612-813-3628, twsamuelson@mneye.com Sarkisian: 405-271-1093, Steven-Sarkisian@dmei.org Glaucoma continued from page 15 Tel: +65 64936953 Fax: +65 64936955