title: The effect of smoking on the risk of primary open-angle glaucoma: an updated meta-analysis of six observational studies.
abstract: OBJECTIVE
  Several studies have investigated the role of smoking on primary open-angle glaucoma (POAG), but the results still remain controversial. We therefore aimed to estimate the effect of smoking on developing POAG.
  
  
  METHODS
  A meta-analysis was conducted from 1 January 1966 to 1 December 2015.
  
  
  METHODS
  We systematically retrieved the relevant studies reporting the association between smoking and POAG using the Cochrane Library, PubMed, and Embase databases. Data were extracted from applicable articles, and effect values were pooled by RevMan 5.3 software.
  
  
  RESULTS
  Six observational studies (three cohort and three case-control studies) fulfilled the inclusion criteria. We found no evidence of publication bias or heterogeneity among all the included studies. A fixed-effects model was performed to pool the relative risks [RRs] with 95% confidence intervals [CIs]. Both current smokers (pooled adjusted RR = 0.97, 95% CI 0.81-1.16, P = 0.74, I2= 38%) and former smokers (RR = 0.97, 95% CI 0.83-1.13, P = 0.66, I2= 46%) had no statistical significant association with POAG compared with never smokers. The sensitivity analysis indicated the pooled results were not significantly changed.
  
  
  CONCLUSIONS
  Our meta-analysis results suggest that there may be not a causal association between smoking and development of POAG.
authors.affiliation: Ophthalmology Department, the Second Affiliated Hospital of Nanchang University, Jiangxi, 330006, China. Electronic address: 1025317142@qq.com.
authors.forename: Y
authors.initials: Y
authors.lastname: Zhou
authors.affiliation: Cardiology Department, the Second Affiliated Hospital of Nanchang University, Jiangxi, 330006, China. Electronic address: 602701970@qq.com.
authors.forename: W
authors.initials: W
authors.lastname: Zhu
authors.affiliation: Ophthalmology Department, the Second Affiliated Hospital of Nanchang University, Jiangxi, 330006, China. Electronic address: ccyywang@hotmail.com.
authors.forename: C
authors.initials: C
authors.lastname: Wang
mesh_terms: D016022:Case-Control Studies; D015331:Cohort Studies; D005902:Glaucoma, Open-Angle / Q000453:epidemiology*; D006801:Humans; D012306:Risk; D012907:Smoking / Q000009:adverse effects*
keywords: Glaucoma; Risk factor; Smoking; Tobacco