The purpose of this document is to describe nonpenetrating glaucoma surgery and to examine the available evidence to assess the efficacy and complications following the procedures.A literature search that was conducted in February 2000 and repeated in September 2000 for the years 1968 to 2000 retrieved over 100 citations that matched the search criteria. Thirty three articles were selected as relevant to the assessment, and they were each evaluated by the panel methodologist for the quality of the evidence presented.One randomized controlled trial comparing nonpenetrating deep sclerectomy to trabeculectomy has been reported. The majority of the published literature contains information from case series, which are not randomized and lack a control group. The two major variations of nonpenetrating glaucoma surgery described in the literature are nonpenetrating deep sclerectomy and viscocanalostomy. The procedures are not familiar to many ophthalmologists, and reports often describe a difficult learning period. These procedures appear to lower intraocular pressure, usually to the mid to high teens, although follow-up is limited in most published reports. Postoperative complications due to overfiltration and hypotony are uncommon in the literature. There is no strong evidence indicating the mechanism of action, reports on bleb formation are lacking, and clinical correlation and gonioscopic findings have been minimal.Nonpenetrating glaucoma surgery has the potential to reduce intraocular pressure while minimizing the risk of postoperative relative hypotony and the complications associated with hypotony. Randomized clinical trials are needed to assess these procedures and to determine their role in the clinical management of glaucoma patients.