ObjectiveTo observe the changes of retinal blood flow density and thickness in the macular region of eyes with high myopia (HM) combined with peripapillary intrachoroidal cavitation (PICC). MethodsA cross-sectional study. From March 2019 to May 2021, 65 patients (65 eyes) diagnosed as PICC (HM+PICC group) in Eye Hospital, China Academy of Chinese Medical Sciences, sex-and age-matched 69 HM patients of 69 eyes (HM group) and 65 healthy people of 65 eyes (control group) were enrolled in this study. The optical coherence tomography angiography was used to scan macular areas in 3 mm×3 mm, and measure the macular fovea and optic disc on superior, inferior, nasal, temporal superficial capillary plexus (SCP) and deep capillary plexus (DCP) vessel density in the foveal and parafoveal region, and macular retinal ganglion cell complex (mGCC) thickness, full retinal thickness. One-way analysis of variance were used to test the difference of the index values among three groups, and then two groups were compared with Bonferroni test. A paired t-test was used to test the difference of the macular vessel density and thickness between the superior and inferior hemifield in three groups. Pearson partial regression analysis was used to calculate the correlations between them at same sites. ResultsPICC was located most frequently at the inferior temporal disc border, followed by the inferior nasal region, superior temporal region, and superior nasal region in the HM+PICC group on 57(87.7%, 57/65), 25(38.5%, 25/65), 3(4.6%, 3/65) and 1(1.5%, 1/65 ) eye. There were significant differences in the global and regional full retinal thickness, mGCC thickness, SCP and DCP vessel density among 3 groups (F=29.097, 51.929, 16.253, 6.135; P＜0.001). The macular SCP and DCP vessel density except in the fovea, all regional macular full retinal thickness and mGCC thickness in the HM+PICC group were significantly lower than those in the normal group (P＜0.05). Compared to the HM group, the HM+PICC group had lower all regional mGCC thickness and SCP vessel density, as well as full retinal thickness in the inferior hemifield and DCP vessel density in the foveal region (P＜0.05). Macular vessel density and thickness in the inferior hemifield were significantly lower than those in the superior hemifield (t=6.356, 11.693, 6.212, 2.936; P＜0.01). Pearson partial regression analysis showed the SCP vessel density was positively correlated with corresponding mGCC thickness and full retinal thickness (r=0.584, 0.534, 0.592, 0.496, 0.485, 0.517; P＜0.001). However, there was no significant correlation between the DCP vascular density and mGCC thickness (P＞0.05), and only a weak positive correlation between the DCP vascular density and the full retinal thickness in the inferior hemifield (r=0.319, P=0.014). However, no association with average and superior full retinal thickness (r=0.066, 0.002, 0.125, 0.184, 0.016, 0.319; P＞0.05). ConclusionThe macular SCP vessel density, mGCC thickness and the full retinal thickness in the inferior hemifield in PICC eyes are lower than those in the HM eyes, especially the mGCC thickness and SCP vessel density in the inferior hemifield, and there is a strong positive correlation between them.