Macular Structures and Microcirculation in High Myopia of different diopters

To investigate the macular structures and microcirculation characteristics in high myopia (HM) of different diopters (D).

A total of 135 HM eyes were included. The HM patients were divided into three groups (group 1 > -8.00 D, group 2 is between -8.00 to -10.00 D, group 3 ≤ -10.00 D). Swept‑source optical coherence tomography (SS‑OCT) and OCT angiography (OCTA) were applied to acquire macular retinal thickness (RT) and retinal vascular density (RVD) in five macular subfields (fovea, superior, nasal, inferior, temporal). Group comparisons were performed using the Kruskal‑Wallis H test with Dunn's post‑hoc test. Multivariable linear regression was used to analyse independent associations between RVD and clinical parameters including axial length (AL), age, intraocular pressure (IOP), and best‑corrected visual acuity (BCVA). A two-tailed *p*-value < 0.05 was considered statistically significant.

Group 3 had significantly longer AL than Groups 1 and 2 (P < 0.001). No intergroup differences were found for regional macular RT (all P > 0.05). Significant inter‑group differences were observed for inferior‑sector (P = 0.029) and temporal‑sector RVD (P = 0.015). Post‑hoc comparisons demonstrated higher inferior‑sector RVD in Group 1 versus Group 2 (P = 0.024), and higher temporal‑sector RVD in Group 1 versus Group 2 (P = 0.012) and Group 3 (P = 0.041). Multivariable regression showed that longer AL was an independent negative predictor of parafoveal RVD across four subfields in Group 1, and of temporal‑sector RVD in Group 2. Elevated intraocular pressure was positively associated with superior‑sector RVD in Group 2. Foveal RT was independently and positively correlated with foveal RVD in both Group 1 and Group 3, whereas no significant RT‑RVD coupling was detected in any parafoveal subfield. No independent predictors of RVD were identified in Group 3, possibly due to limited sample size.

HM produces region‑specific, non‑linear macular microvascular alterations modulated by myopia severity, AL, and foveal retinal thickness. Microvascular impairment can occur without measurable macular retinal thinning, and foveal structure‑perfusion coupling exists in moderately and extremely HM. Dioptric‑stratified subfield‑based OCTA assessment facilitates risk surveillance in HM eyes.