Changes in ocular blood flow and haemodynamic waveform parameters following trabeculectomy.

Abstract

Objectives: To evaluate postoperative changes in ocular blood flow velocity and waveform parameters measured by laser speckle flowgraphy (LSFG) following trabeculectomy (TLE) in patients with glaucoma.

Methods and analysis: This retrospective study included 80 eyes of 80 patients with glaucoma who underwent TLE and underwent LSFG examinations before and at 1, 3 and 6 months after surgery. LSFG-derived blood flow velocity parameters (mean blur rate (MBR) in MBR of vascular area (MV) and MBR of tissue area (MT), area ratio of blood speed and vascular cloudiness) and waveform parameters (blowout time, blowout score (BOS), skew, acceleration time index, rising rate, falling rate, flow acceleration index (FAI), resistivity index (RI) and fluctuation) were longitudinally evaluated using linear mixed-effects models.

Results: Intraocular pressure (IOP) significantly decreased from 18.3 mm Hg preoperatively to 10.1, 10.0 and 9.9 mm Hg at 1, 3 and 6 months after TLE, respectively (all p<0.01). MV significantly decreased at all postoperative time points (all p<0.01), whereas MT showed a mild decrease only at 6 months (p=0.023). Among waveform parameters, BOS significantly increased postoperatively (all p<0.05), whereas FAI, RI and fluctuation significantly decreased at all postoperative time points (all p<0.01). IOP measured at each visit was independently associated with FAI and fluctuation, whereas age, mean deviation (MD) and axial length (AL) were associated with selected blood flow velocity and waveform parameters.

Conclusion: These findings suggest that postoperative changes in ocular haemodynamics reflect the combined influence of postoperative IOP, patient age, MD and AL.