The peripapillary retinal capillary density is highly correlated with its nerve fibre layer in normal population.

Abstract

To explore the peripapillary capillary density distribution and its correlation with nerve fibre layer in superficial and deep retinal layers of healthy Chinese. Images of superficial and deep retinal capillary networks were obtained by optical coherence tomography angiography (OCTA) using a CIRRUS TM HD-OCT Model 5000 system and analyzed by Image-Pro Plus (Medical Cybernetics, Version 6.0). Peripapillary capillary density was defined as the mean optical density of the annular region between two concentric circles of 3.085 mm and 3.835 mm diameter. Parafoveal capillary density was defined as the mean optical density between the foveal avascular zone (FAZ) boarder and a 2.5 mm diameter circle. Retinal nerve fibre layer (RNFL) thickness was also measured and the correlation with capillary density determined. Mean peripapillary capillary density was 4.16±1.06 in the superficial and 2.92±0.80 in the deep layer. Corresponding mean parafoveal densities were 2.65±0.55 and 2.51±0.55. Capillary densities were higher in the superficial layer of all quadrants for both peripapillary and parafoveal regions (P < 0.001). A significant correlation between peripapillary capillary density and RNFL thickness was found in the superficial layer (r = 0.305, P < 0.05). A negative correlation between age and capillary density was found in both peripapillary and parafoveal regions (P < 0.001). Peripapillary capillary density in the superficial layer highly correlated with RNFL thickness. Regional and age-related differences in peripapillary and parafoveal capillary density should be considered when diagnosing and monitoring individuals with diseases affecting retinal capillary density.