Effects Of Cigarette Smoking On Choroidal And Retinal Thickness:A Systematic Review And Meta-analysis

Background: Cigarette smoking has been regarded as a risk factor for the incidence of a wide variety of chronic illness,however,its effect on thickness of retina or choroid is still unknown.In order to further understand the influence of smoking on retinal choroid thickness,the data obtained through Meta-analysis were evaluated.Methods: A consummate literature search was conducted in Pubmed and EMBASE up to Jan,2018.We conducted a Meta-analysis of the relevant literature to assess the effect of smoking on the thickness of the retina and choroid.The relationship between smoking and retinal choroid thickness was assessed using the standard mean difference(SMD)of 95% confidence interval(CI,95% CI).Quantitative synthesis was performed through Stata 12.0.The presence of heterogeneity in the effect was assessed using the ?2 test and the I2 test.At the same time,Begg's and Egger's tests were used to test publication bias.Sensitivity analysis was used to determine whether any of the included articles had an impact on the overall results of the study.Results: A total of 13 observational studies were included in this Meta-analysis.In this Meta-analysis of all available observational studies,no significant effect of tobacco smoking on retinal or choroidal thickness change was detected.However,advanced analyses showed that smoking would influence the thickness of RNFL(average: SMD,-0.332,95% CI,-0.637 to-0.027;inferior: SMD,-0.632;95% CI,-1.092 to-0.172,and superior: SMD,-0.720;95% CI,-0.977 to-0.463)and GCL(superior: SMD,-0.549;95% CI,-0.884 to-0.215,and inferior: SMD,-0.602;95% CI,-0.938 to-0.265).Besides,subgroup analyses demonstrated that the results based on studies in some regions(America and Africa)and cross-sectional studies showed a reduced choroidal thickness in smokers.No publication bias was detected in this study.Conclusion: In conclusion,no significant effect of tobacco smoking on retinal or choroidal thickness change was detected.However,smoking would influence the thickness of RNFL and GCL.Future research on this field would help in the prevention and treatment of smoking associated disorders.