Correlation of optic disc morphometry and optic disc microvasculature assessed with optical coherence tomography angiography

Objective: To compare optic disc microvasculature measurements to the disc morphometrics in normal eyes. Design: Cross-sectional study. Participants: Fifty-eight healthy subjects. Methods: Enface 4.5x4.5 mm optical coherence tomography angiography images were obtained from the optic disc of healthy individuals. The radial peripapillary capillary (RPC) and the nerve head (NH) en face images were obtained. Also, spectral domain OCT measurements of the peripapillary nerve fibre layer (NFL) thickness were recorded. Correlations of the vessel density and NFL measurements with optic disc morphometrics were analyzed. Results: Fifty-eight eyes of 58 patients were included. Mean peripapillary NFL thickness was 99.77 +/- 8.47 mu m The mean disc area was 2.15 +/- 0.34 mm(2) (range, 1.48-3.02 mm(2)) with an average cup/disc area ratio of 0.27 +/- 0.14 (range, 0.0-0.6). On the RPC en face image, the mean vessel density of the whole image, peripapillary, and inside disc was 55.52 +/- 2.90, 62.42 +/- 3.30, and 45.77 +/- 9.24%, respectively. On the NH en face images, the mean vessel density of the whole image, peripapillary, and inside disc was 55.69 +/- 3.04, 60.15 +/- 2.79, and 52.69 +/- 5.31%, respectively. The NH vessel density in the inside disc area correlated with the cup/disc area ratio (R = -0.44, p < 0.001). The association of RPC vessel density in the inside disc area with the cup/disc area ratio was significant (R= -0.88, p < 0.001). The RPC vessel density in the peripapillary area correlated with the cup/disc area ratio (R = 0.37, p= 0.004). Also, the RPC vessel density in the whole image was associated with the peripapillary NFL thickness (R = 0.32, p = 0.01). Conclusion: We observed a significant negative correlation between inside disc vessel density and cup/disc area ratio, but not to the disc area in normal eyes. In addition, the whole image RPC vessel density was revealed to be weakly correlated with the average RNFL thickness.