title: Myopia and/or longer axial length are protective against diabetic retinopathy: a meta-analysis.
abstract: OBJECTIVE
  To evaluate the current evidence of the relationship between myopia, together with its structural and refractive component, and diabetic retinopathy (DR) risk.
  
  
  METHODS
  A systematic search was performed up to April, 2015. Summary odds ratios (ORs) and 95% confidence intervals (CIs) were calculated employing random-effects models. Three models were used to assess the association between myopia and risk of DR: axial length (AL) (per millimetre increase) and DR; myopia (myopia versus non-myopia) and DR; refractive error (RE) (per D decrease) and DR. Publication bias of the literature was evaluated using Begg's funnel plots and Egger's test.
  
  
  RESULTS
  A total of 11 studies that met the predefined criteria were included in this meta-analysis. Overall, longer AL (per millimetre increase) was associa-ted with a significantly decreased risk of DR (combined OR, 0.75; 95% CI, 0.65-0.86; p < 0.001); myopic eyes (myopia versus non-myopia) showed a lower risk of DR (combined OR, 0.70; 95% CI, 0.58-0.85; p < 0.001). A greater degree of myopic RE (per D decrease) also revealed a significantly decreased risk of DR (combined OR, 0.89; 95% CI, 0.85-0.93; p < 0.001). The sensitivity analyses and cumulative meta-analysis showed similar results. No publication bias was detected in any of the three models.
  
  
  CONCLUSIONS
  This meta-analysis suggests that both myopic refraction and longer AL are associated with a lower risk of DR. Further studies are needed to determine exact mechanisms underpinning the protective effect of myopia against DR.
authors.affiliation: Sun Yat-sen Memorial Hospital, Sun Yat-sen University, Guangzhou, China.
authors.forename: Yu
authors.initials: Y
authors.lastname: Fu
authors.affiliation: Sun Yat-sen Memorial Hospital, Sun Yat-sen University, Guangzhou, China.
authors.forename: Dengfeng
authors.initials: D
authors.lastname: Geng
authors.affiliation: Department of Ophthalmology, Liaoning Medical University, Jinzhou, Liaoning, China.
authors.forename: Hua
authors.initials: H
authors.lastname: Liu
authors.affiliation: Department of Ophthalmology, The Third Affiliated Hospital of Liaoning Medical University, Jinzhou, Liaoning, China.
authors.forename: Huixin
authors.initials: H
authors.lastname: Che
mesh_terms: D058452:Axial Length, Eye / Q000473:pathology*; D003930:Diabetic Retinopathy / Q000503:physiopathology / Q000517:prevention & control*; D006801:Humans; D009216:Myopia / Q000150:complications* / Q000503:physiopathology; D016017:Odds Ratio; D012307:Risk Factors
keywords: axial length; diabetic retinopathy; meta-analysis; myopia