Diagnostic performance of optical coherence tomography angiography in glaucoma: a systematic review and meta-analysis

Background Compared with current imaging methods, the diagnostic performance and the advantages and limitations of optical coherence tomography angiography (OCTA) remain unclear. We performed a systematic review and meta-analysis of studies investigating vessel density (VD) in patients with glaucoma using OCTA. Methods We conducted a literature search on PubMed, Scopus, Web of Science, ISI Conference Proceedings and Google Scholar, along with a manual search, from January 2006 to March 2018. We included prospective studies that used OCTA to compare the VD in glaucomatous eyes with healthy control eyes. Results Of 3045 screened articles, 24 were included in a broad characterisation and 18 in the meta-analysis. We observed a statistically significant reduction in the mean peripapillary VD (MPVD) in glaucoma (MPVD: 57.53%, 95% CI 52.60 to 62.46, p< 0.001) compared with controls (MPVD: 65.47%, 95% CI 59.82 to 71.11; standardised mean difference [SMD], –1.41, 95% CI –1.62 to –1.20, p< 0.001) for 888 glaucomatous and 475 healthy eyes, and also in the mean-whole optic nerve image VD (SMD, –9.63, 95% CI –10.22 to –9.03, p<0.001), mean inside-disc VD (SMD, − 9.51, 95% CI –12.66 to –6.36, p<0.05) and mean parafoveal VD (SMD, –3.92, 95% CI –4.73 to –3.12, p<0.001). Subgroup analyses revealed a significant difference in the MPVD across glaucoma subtypes and OCTA devices. Conclusion This suggests the diagnostic utility of OCTA in detecting glaucomatous eyes; however, further longitudinal prospective studies are welcomed to characterise vascular changes in glaucoma.