Changes in peripapillary and macular vascular density after laser selective trabeculoplasty: an optical coherence tomography angiography study.

Abstract

To determine the effect of laser trabeculoplasty on peripapillary retinal nerve fibre layer thickness (RNFL), fovea avascular zone (FAZ), peripapillary and macular vessel density (VD) in glaucoma using with optical coherence tomography angiography (OCT-A). This was a prospective observational study performed at the Glaucoma Research Centre, Montchoisi Clinic, Lausanne, Switzerland. Thirty-seven eyes with primary open-angle glaucoma from 21 patients were included. Optical coherence tomography angiography (OCT-A) scans were performed before laser trabeculoplasty and at 2 and 6 months after the procedure. AngioVue AngioAnalytic (Optovue Inc, Fremont, CA, USA) software was used to analyse the RNFL, FAZ, peripapillary and macular VD. Changes were analysed using mixed models, controlling for intraocular pressure (IOP) and signal strength index (SSI) variations. Mean IOP decreased from 18.5 (±3.7) mmHg at baseline to 15.6 (±2.7) mmHg after 2 months (-15.3%; p < 0.001). No significant changes in RNFL thickness were noted following laser trabeculoplasty. Changes in peripapillary VD were mostly nonsignificant. Parafoveal (p = 0.001) and perifoveal VD (p = 0.025) significantly increased at 2 months, before reverting to near-baseline values at 6 months. No significant changes were observed in foveal parameters. Retinal nerve fibre layer thickness (RNFL) and VD changes were independent from IOP, but SSI had a significant influence on VD. Following laser trabeculoplasty, peripapillary and macular VD temporarily increased before returning to near-baseline values by 6 months. No correlation was found between microvascular fluctuations and IOP, and no significant effect of laser trabeculoplasty on VD or RNFL was observed at 6 months despite persistent IOP reduction. Further research is warranted to understand its exact causes and clinical relevance.