Prognostic factors of optical coherence tomography angiography in intermediate and advanced primary open‐angle glaucoma: A systematic review and meta‐analysis

Conventional optical coherence tomography (OCT) has a floor effect in patients with severe visual field loss, such as seen in advanced primary open-angle glaucoma (POAG). OCT angiography (OCTA) does not suffer from such a floor effect. However, which OCTA parameters are most useful for monitoring longitudinal progression is unclear. We conducted a systematic review and meta-analysis to investigate the clinical use of OCTA in monitoring the progression of intermediate and advanced POAG by searching four databases (Medline, Embase, Web of Science and Cochrane Database of Systematic Reviews) for longitudinal studies on POAG and OCTA. For each meta-analysed OCTA parameter, we calculated a pooled effect estimate with a 95% confidence interval (95% CI). Parameters that could not be meta-analysed were compared narratively. A total of 18 studies were included in the systematic review and seven in the meta-analyses. In the meta-analyses, a lower baseline peripapillary vessel density (VD) significantly increased the risk of visual field (VF) progression (HR [95% CI]: 1.05 [1.02, 1.07] for each percentage decrease in peripapillary VD per year). Baseline parafoveal VD and risk of VF progression showed no significant association. The inferior hemifield foveal avascular zone parameters and the presence of peripapillary choroidal microvascular dropout were significantly associated with the risk of VF progression in the systematic review. Peripapillary VD may be a useful predictor of VF progression in intermediate and advanced glaucoma patients. Although FAZ and MvD also seem to be potential predictors, longitudinal studies on advanced POAG are limited and heterogeneous, highlighting the need for more consistent and comprehensive research.