AIM: To compare the optic disc microvessel density(MVD)with different degrees of myopia and to evaluate the association of MVD with axial length(AL)and retinal nerve fibre layer thickness(RNFL)by using optical coherence tomography angiography(OCTA).

METHODS: Prospective and pathological control study. A total of 94 eyes \〖31 eyes with mild myopia(SE: +0.50D to -0.50D), 32 eyes with low and moderate myopia(-0.75D≤SE<-6.00D), and 31 eyes with high myopia(SE≥-6.00D)\〗 underwent optical coherence tomography angiography imaging. OCTA was used to image 4.5mm×4.5mm scanning area centered on the subject's optic disc, and to automatically and quantitatively measure the MVD and RNFL thickness in different partitions of the optic disc in order to carry out relevant discussions.

RESULTS: Among ISNT partition, temporal RNFL thickness was positively correlated with AL(r=0.343, P<0.05). RNFL thickness in the nasal, inferior and superior quadrants was negatively correlated with AL(r=-0.341, -0.289, -0.269, all P<0.05). In Garway Heath partition, temporal superior RNFL thickness was positively correlated with AL(r=0.382, P<0.05). Negative correlations were found in the thickness of RNFL with AL at the nasal superior, nasal inferior and inferior nasal quadrant(r=-0.226, -0.211, -0.369, -0.316, -0.304, -0.241, all P<0.05). The overall MVD in optic disc increased with the increase of AL(r=0.376, P<0.05), while the overall MVD around optic disc was negatively correlated with AL(r=-0.361, P<0.05).

CONCLUSION: The change of MVD and RNFL thickness of optic disc are closely related to AL. With the increase of AL, the thickness of RNFL and MVD in the nasal superior, nasal inferior and inferior nasal quadratons decreased, the overall MVD in optic disc decreased, and the MVD in optic disc and the temporal superior quadratons increased, especially in high myopia.