A meta-analysis of retinal vascular density in different severities of myopia assessed by optical coherence tomography angiography

Abstract

Purpose: To evaluate the impact of myopia severity (mild, moderate or high) on retinal vascular density (VD) and the foveal avascular zone (FAZ) using optical coherence tomography angiography (OCTA).

Methods: Studies were included based on the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Inclusion criteria required studies reporting mean VD or FAZ for three severities of myopia. The quality assessment followed the Newcastle-Ottawa Scale (NOS). Data were pooled using fixed- or random-effects models depending on heterogeneity. The research protocol was published in the Prospective Register of Systematic Reviews (PROSPERO) with registration number CRD42025638165.

Results: Twelve studies (2302 eyes) met the inclusion criteria. VD was assessed in both macular (foveal, parafoveal and perifoveal) and peripapillary regions, depending on the included study, and showed a decrease in the superficial capillary plexus (SCP) with increasing myopia severity, while the FAZ size remained relatively stable across groups. High myopia was associated with lower VD, particularly in the foveal and parafoveal regions in both the SCP and deep capillary plexus (DCP). VD in the foveal SCP was higher in mild (24.13%) compared to high myopia (20.59%). Similarly, parafoveal VD in the SCP was 52.53% and 49.66% in mild and high myopia, respectively. FAZ size remained relatively stable across groups, ranging from 0.30 to 0.32 mm².

Conclusion: This meta-analysis demonstrates that high myopia is associated with a lower VD, particularly in SCP, with no consistent enlargement of the FAZ. The findings highlight the progressive impact of myopia severity on retinal microvasculature.

Keywords: foveal avascular zone; macular microvasculature; myopia; optical coherence tomography angiography; vessel density.