Moving the Goal Posts: Definitions of Success after Glaucoma Surgery and Their Effect on Reported Outcome

To determine (1) the extent to which the definition of success of glaucoma surgery varies in the literature and (2) the degree to which the reported outcome after trabeculectomy is affected by the criteria used to define success. A systematic review of the literature and application of definitions to a retrospective cohort. A cohort of 100 patients who previously underwent trabeculectomy. A literature search was performed of PubMed using the search term trabeculectomy for a 5-year period. Studies presenting original data relating to longitudinal intraocular pressure (IOP) control after glaucoma surgery were included. The definitions of success and failure used were documented for each publication. Each IOP-related definition of success was applied to a cohort of patients who previously underwent trabeculectomy. Success rates were derived for each published definition up to 36 months after surgery. Intraocular pressure measured by Goldmann applanation tonometry. From 100 publications meeting the inclusion criteria, 92 distinct IOP-related definitions of success were identified. Using these definitions, success rates for this series of 100 trabeculectomies varied between 36.0% and 98.0% after 3 years of follow-up. Over a recent 5-year period, there were nearly as many different definitions of success after glaucoma surgery as publications on the subject. The definition used markedly affects the quoted success rate after trabeculectomy, making interpretation of and comparison between published results extremely difficult. Standardization of published outcome parameters after glaucoma surgery is essential to allow meaningful comparisons between different study reports. The author(s) have no proprietary or commercial interest in any materials discussed in this article.