Repeatability of Retrobulbar Blood Flow Velocity Measured Using Color Doppler Imaging in the Indianapolis Glaucoma Progression Study

Abstract

Determine the repeatability of color Doppler imaging (CDI) measurements in patients with open-angle glaucoma (OAG). We performed a cross-sectional, observational study of OAG patients participating in the Indianapolis Glaucoma Progression Study. Retrobulbar blood flow velocities and Pourcelot's vascular resistance index (RI) measured with CDI were examined. Two baseline measurements were obtained 1 to 2 weeks apart at the same time of day for all participants. Peak systolic and end diastolic blood flow velocities (PSV/EDV) were measured in the ophthalmic (OA), central retinal (CRA), and nasal and temporal short posterior ciliary arteries (N/TPCA) and RI was calculated. Intraclass correlation coefficient (ICC) between the 2 baselines was calculated. One hundred and sixteen patients with OAG [mean age 65.9 y (SD 10.9 y), 60% female] were examined in both baseline visits. In the OA, the intraobserver ICC for the PSV, EDV, and RI were all above 0.82. In the CRA, the intraobserver ICC for the PSV and RI were both above 0.8, whereas the EDV was 0.64. The intraobserver ICC in the N/TPCA for the PSV, EDV, and RI ranged from 0.71 to 0.88. The interobserver ICC was similar to the intraobserver ICC for the OA and the CRA but was lower than 0.7 in the EDV and RI of the T/NPCA. Blood flow velocities and calculated vascular resistance of the OA, CRA, and PCAs conducted within 2 weeks in patients with OAG are repeatable. Intraobserver CDI measurements were found more reproducible than interobserver CDI analysis.