Figure 2. Forest plot comparing efficacy of WFG-PRK and Non-WFG-PRK.

Each study is represented by a square at the point of treatment effect, and the area of the square is proportional to the weighting of that study in the analysis. A horizontal line on either side of each square represents the CI. The diamond at the bottom of the plot represents the overall treatment effect determined by the position at the center of the diamond and the CI of the combined data conveyed by the width of the diamond. WFG-PRK =  wavefront guided photorefractive keratectomy, Non-WFG-PRK =  non-wavefront guided photorefractive keratectomy, M-H = Mantel-Haenszel, CI = confidence interval, Chi² = chi-square statistic, df = degrees of freedom, I² = I-square heterogeneity statistic, Z = Z-statistic.