It is with great interest that I read the article by Iwao and associates on the success of trabeculotomy in steroid glaucoma. There has been a long-felt need for studies looking at alternatives to trabeculectomy in glaucoma that can minimize surgical complications while providing adequate long-term intraocular pressure (IOP) control. So this multicenter study assumes great importance since it tries to rigorously address the issue of trabeculotomy vs trabeculectomy in steroid glaucoma.
It was therefore very impressive that the 3-year success of trabeculotomy for steroid-induced glaucoma in this study was comparable to trabeculectomy for criterion A (83.8%), implying equal IOP control with trabeculotomy. Yet, a detailed analysis and reexamination into the results fails to convince us of the better success of trabeculotomy. Herein are some of the reasons why the results seem to be confounded by the intricacies in the study outcomes and therefore cannot be applied to general practice.
The author’s primary outcome was probability of success; failure has been defined as IOP > 21 mm Hg (criterion A) or > 18 mm Hg (criterion B) with or without medications. This implies that qualified and complete success have not been separately defined into the success criteria, which is of utmost importance in defining surgical success after glaucoma filtering surgery. Some of the patients post-trabeculotomy may have been on antiglaucoma medications for IOP fluctuations, which would still be a “success” as per their definition. Without this information, these results cannot be considered to represent the true clinical scenario. Further, 7 trabeculectomy eyes failed at 5 years vs 22 in the trabeculotomy group, implying a better success of the former, which is contrary to what the authors try to convey or prove.
Further, the need for surgery postoperatively has been considered as “failure.” It is not clear if a better success of trabeculotomy in steroid glaucoma compared to primary open-angle glaucoma (POAG) patients is attributable to a bias of the treating physician toward re-surgery in adult POAG patients as opposed to medical management in younger patients, falsely raising the “failure” rate in POAG.
The goal of any filtering surgery is to give long-term IOP control and preservation of visual function with minimal risk, without the need for repeat surgery or medications. Trabeculectomy no doubt is wrought with many complications; yet these are not universal and surgical modifications can be applied to minimize the same. Despite the inherent limitations of a retrospective design, this study tries to address an important question. Yet the results cannot be extrapolated to general practice, and adequate information on the IOP control with and without medications should be discussed before trabeculotomy is accepted as comparable to trabeculectomy in steroid glaucoma.