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Abstract

TO THE EDITOR: I read with interest the retrospective, comparative study by Panarelli et al 1 comparing the safety and efficacy of Baerveldt implantation with that of trabeculectomy with mitomycin C (MMC) in patients who have not undergone prior incisional ocular surgery. The authors reported a comparable surgical success rate between patients who have undergone trabeculectomy with MMC and those who have undergone Baerveldt implantation.The authors included patients who underwent either primary trabeculectomy with MMC or 350-mm 2 Baerveldt shunt placement between 1985 and 2010. However, the Baerveldt shunt was first introduced in 1992. 2,3 I, therefore, do not understand the authors' inclusion of patients from 1985 to 1992.In this retrospective study, the authors found a comparable surgical success rate between the 2 operative procedures. Conversely, the "tube (Baerveldt shunt) versus trabeculectomy (TVT)" study, 4 which compared trabeculectomy with MMC and Baerveldt implantation, showed that the success rate of trabeculectomy was lower than that of Baerveldt implantation. Regarding this difference in success rates, the authors mentioned some possible causes, including patient characteristics (e.g., the TVT study included patients who had undergone previous trabeculectomy, cataract extraction with intraocular lens implantation, or both while the Panarelli et al study only enrolled patients who had not undergone prior incisional ocular surgery), success or failure criteria, and duration of follow-up. 1 Other possible causes of the different study outcomes include that the TVT study was a multicenter randomized clinical trial with a large sample size. The randomized design eliminated the possible confounding factors between the 2 groups. The 25-year time span of the Panarelli et al 1 retrospective study may have also had an effect on the outcomes, that is, when Baerveldt implantation was first being used, the operative technique and experience were immature. However, during this period, the technique used in trabeculectomy was mature and, as such, it had an advantage over Baerveldt implantation. Thus, it might underestimate the superiority of Baerveldt implantation.