Effect of selective laser trabeculoplasty on ocular haemodynamics in primary open-angle glaucoma

Selective laser trabeculoplasty (SLT) is known to reduce intraocular pressure (IOP) effectively. The aim of this study, however, was to evaluate the effect of SLT on ocular haemodynamics.

A total of 69 eyes of 69 patients (age 67.8 ± 9.9 years) with already treated primary open-angle glaucoma who were assigned for SLT for further IOP reduction were consecutively enrolled in this prospective interventional case series. Intraocular pressure, the ocular pulse amplitude (OPA), ocular pulse volume (OPV) and pulsatile ocular blood flow (pOBF) were assessed with the Ocular Blood Flow Analyzer prior to and 3 months after SLT.

Intraocular pressure was statistically significantly reduced from 16.0 ± 5.4 mmHg to 12.8 ± 4.0 mmHg (p = 0.001). The OPA did not change (p = 0.783) after IOP reduction following SLT. OPV and pOBF increased statistically significantly. OPV increased from 7.33 ± 3.05 to 8.59 ± 3.35 μl (17.2%; p = 0.001) and pOBF from 17.11 ± 5.42 to 19.74 ± 6.59 μl/s (15.4%; p = 0.002).

Selective laser trabeculoplasty probably does not induce any pharmacological changes effecting systemic blood pressure or ocular blood flow as topical IOP-lowering medication might do, nor does it change biomechanical properties of the eye as surgery could. Therefore, an increase in ocular blood flow following SLT can only be explained by the reduction in IOP and might be a sign of dysfunctional autoregulation in glaucoma patients.