title: Comparison of the Ahmed glaucoma valve with the Baerveldt glaucoma implant: a meta-analysis.
abstract: BACKGROUND
  This study aims to compare the efficacy and safety of the Ahmed glaucoma valve (AGV) with the Baerveldt glaucoma implant (BGI) in glaucoma patients.
  
  
  METHODS
  Databases were searched to identify studies that met pre-stated inclusion criteria, involving randomized controlled clinical trials (RCTs) and non-randomized controlled clinical trials. Treatment effect was analyzed using a random-effect model.
  
  
  RESULTS
  Ten controlled clinical trials (1048 eyes) were analyzed, involving two RCTs and eight retrospective comparative studies. Short-term results (6-18 months) and long-term results (>18 months) were analyzed separately. There was no significant difference in the success rate for short-term follow-up between the AGV and BGI groups (5 studies, 714 eyes, odds ratio [OR]: 0.97; 95 % confidence interval [CI]: 0.56, 1.66; P = 0.90). For long-term pooled results (7 studies, 835 eyes), the success rate of AGVs was lower than that of BGIs (OR: 0.73; 95 % CI: 0.54, 0.99, P = 0.04), However, subgroup and sensitivity analyses did not show a significant difference in the success rate between the two groups (P ≥0.05). The AGV group had a higher mean intraocular pressure than the BGI group in short-term (6 studies, 685 eyes, weighted mean difference [WMD]: 2.12 mmHg; 95 % CI: 0.72-3.52; P <0.05) and long-term pooled results (7 studies, 659 eyes, WMD: 1.85 mmHg; 95 % CI: 0.43, 3.28; P = 0.01). The BGI group required fewer glaucoma medications after implantation than the AGV group in two follow-up periods (all P <0.05). The AGV was found to be associated with a significantly lower frequency of total complications (8 studies, 971 eyes, OR: 0.67; 95 % CI: 0.50-0.90; P = 0.007) and severe complications (8 studies, 971 eyes, OR: 0.57; 95 % CI: 0.36-0.91; P = 0.02) than the BGI.
  
  
  CONCLUSIONS
  The study showed no significant difference in success rate between the two groups. The BGI was more effective for control of intraocular pressure and required fewer medications than the AGV, but the AGV had lower incidence of total and severe complications than the BGI.
authors.affiliation: Department of Ophthalmology, Xiangya Hospital, Central South University, #87 Xiangya Road, Changsha, Hunan, 410008, China. ywwang2013@icloud.com.
authors.forename: Yi-Wen
authors.initials: YW
authors.lastname: Wang
authors.affiliation: Department of Ophthalmology, Xiangya Hospital, Central South University, #87 Xiangya Road, Changsha, Hunan, 410008, China. pingbao_wang@hotmail.com.
authors.forename: Ping-Bao
authors.initials: PB
authors.lastname: Wang
authors.affiliation: Department of Orthopaedics, Xiangya Hospital, Central South University, Changsha, Hunan Province, China. zengchao19880505@sina.com.
authors.forename: Chao
authors.initials: C
authors.lastname: Zeng
authors.affiliation: Department of Ophthalmology, Xiangya Hospital, Central South University, #87 Xiangya Road, Changsha, Hunan, 410008, China. xbxia21@163.com.
authors.forename: Xiao-Bo
authors.initials: XB
authors.lastname: Xia
mesh_terms: D018849:Controlled Clinical Trials as Topic; D005500:Follow-Up Studies; D005901:Glaucoma / Q000503:physiopathology / Q000601:surgery*; D020327:Glaucoma Drainage Implants; D006801:Humans; D007429:Intraocular Pressure / Q000502:physiology*; D014065:Tonometry, Ocular