Distribution characteristics of retinal nerve fiber layer thickness in macular area and its relationship with vessel density in highly myopic eyes

AIM: To investigate the distribution characteristics of retinal nerve fiber layer thickness and vessel density in macular area of eyes with high myopia, using optical coherence tomography angiography (OCTA). METHODS: Forty eyes in 20 patients diagnosed with high myopia, age 29.90±7.92 years old, with a spherical equivalent of -8.95±2.01 D, were recruited. The retinal nerve fiber layer (RNFL) thickness and the vessel density of the superficial retinal capillary plexus, deep retinal capillary plexus, and choroidal capillary were measured by OCTA. Macular regions within a 6-mm diameter circle were divided into 9 subfields: the central subfield, and the pericentral and peripheral regions of superior, inferior, nasal, and temporal quadrants. The retinal nerve fiber layer thicknesses of different subfields were compared, and their relationships with spherical equivalent, axial length, and vessel density were analyzed. RESULTS: In the pericentral region, the retinal nerve fiber layer thickness of the superior quadrant was the lowest, whereas thickness was highest in the inferior quadrant (all P<0.05). In the peripheral region, the retinal nerve fiber layer thickness of the temporal quadrant was the lowest (all P<0.05). A negative correlation was found between the retinal nerve fiber layer thickness and spherical equivalent (r=-0.356, P=0.024) in the peripheral superior subfield. The vessel density of superficial retinal capillary plexus was positively correlated with retinal nerve fiber layer thickness in the nasal and inferior quadrants of the pericentral region and in the superior, nasal, and inferior quadrants of the peripheral region (r=0.314, 0.408, 0.467, 0.655, and 0.737 respectively; and all P<0.05), whereas the vessel density of choroidal capillary was negatively correlated with retinal nerve fiber layer thickness in the peripheral superior subfield (r= -0.356, P=0.024). CONCLUSION: The RNFL of macular areas is not uniformly distributed in high myopia (HM). As the spherical equivalent (SE) increases, the RNFL thickness decreases in certain areas, which correlates with the vessel density(VD) of superficial retinal capillary plexus (SCP) and choroidal capillary (CC) layers.