Does medical treatment influence the success of trabeculectomy?

PURPOSE: Many ophthalmologists believe that long-term use of topically applied glaucoma medications can adversely affect results of fistulizing surgery. This presentation critically analyzes the published studies most often cited in support of this view to determine whether this conclusion is justified.
METHODS: Morphologic effects of long-term treatment with antiglaucoma drugs on the conjunctiva and Tenon's capsule in glaucomatous patients have been studied. The results of these studies encouraged investigators to examine the influence of prior therapy on the success of trabeculectomy performed in patients with open-angle glaucoma. From this work, many have concluded that long-term use of topically applied glaucoma medications can adversely affect the results of fistulizing surgery. These results and conclusions are summarized and critically analyzed to determine whether this conclusion is justified.
RESULTS: Morphologic studies describe increased numbers of macrophages, fibroblasts, lymphocytes, and mast cells in conjunctival and Tenon's capsule specimens taken from patients receiving long-term antiglaucoma drugs. These findings suggest a potential for more inflammation and subsequent scarring following trabeculectomies in these patients. Efforts to confirm the clinical relevance of these histologic findings in open-angle glaucoma patients with a history of long-term antiglaucoma medication prior to surgery have been published. These retrospective, nonrandomized, unmasked studies of open-angle glaucoma patients include treatment groups and surgeries that are not comparable. In addition, the medical treatments within these studies do not reflect our current approaches to the medical management of open-angle glaucoma.
CONCLUSIONS: At present, there is no convincing clinical evidence that long-term medical treatments influence the success of contemporary trabeculectomy surgery performed on open-angle glaucoma patients.