Effect of surgical intraocular pressure lowering on retinal structures-nerve fibre layer, foveal avascular zone, peripapillary and macular vessel density: 1 year results

Abstract

We recently read a published paper by Ch'ng et al. [1] entitled "Effect of surgical intraocular pressure lowering on retinal structures nerve fibre layer, foveal avascular zone, peripapillary and macular vessel density: 1 year results". In this study the above-mentioned authors evaluated the effect of surgical intraocular pressure (IOP) lowering on peripapillary retinal nerve fibre layer thickness (RNFL), fovea avascular zone (FAZ), peripapillary and macular vessel density (VD) in glaucoma using optical coherence tomography angiography (OCT-A). In this regard, they performed serial OCT-A scans in 40 eyes with open-angle glaucoma before glaucoma surgery, and at 1-month, 3-month, 6-month and 12-month post-operatively and assessed IOP, RNFL, FAZ and VD at the same times. Because they evaluated the IOP, RNFL, FAZ and VD in the same patients in five time-points of assessment, therefore their comparisons are in category of dependent comparisons. As stated in the statistical analysis section, Table 2 and Fig. 3 of the article, the authors used one-way analysis of variance (ANOVA) and Kruskal Wallis tests to compare means of IOP, RNFL, FAZ and VD before glaucoma surgery, at 1-month, 3-month, 6-month and 12-month post-operatively. They also used Post-hoc tests for pairwise comparisons of measurements between the visits