Effects of Trabeculectomy on Waveform Changes of Laser Speckle Flowgraphy in Open Angle Glaucoma.

ABSTRACT

Purpose: To investigate the effect of trabeculectomy on the waveform changes of laser speckle flowgraphy (LSFG) in the optic nerve head (ONH) in patients with glaucoma. Methods: Forty-eight eyes of 48 patients with open angle glaucoma were included in this prospective study. LSFG was performed before and 1, 3, and 6 months after trabeculectomy. Longitudinal changes in average mean blur rate (MBR), blow out score (BOS), resistivity index (RI), falling rate, skew, acceleration time index, and blow out time in the tissue area of the ONH were analyzed by using mixed-effects models. Results: Intraocular pressure (IOP) decreased and ocular perfusion pressure increased significantly at each postoperative time point (P < 0.001, each). BOS increased (P < 0.001, each) and RI decreased (P < 0.001, each) significantly at each postoperative time point, although average MBR and other waveform parameters did not change significantly. Multivariate analyses revealed that younger age (coefficients = -0.13 and 0.0014, P = 0.006 and 0.03 for BOS change and RI change, respectively), worse baseline mean deviation of visual fields (coefficients = -0.18 and 0.0026, P = 0.009 and 0.005), larger IOP reduction (coefficients = -0.29 and 0.0037, P < 0.001, each), and larger pulse rate increase (coefficients = 0.17 and -0.0024, P < 0.001, each) are significantly associated with postoperative BOS increase and RI decrease. Conclusions: Given that postoperative BOS increased and RI decreased with the average MBR remaining unchanged, IOP reduction by trabeculectomy may contribute to stable blood flow throughout the duration of the heartbeat in the tissue area of the ONH.