Argon versus selective laser trabeculoplasty

To compare conventional argon laser trabeculoplasty (ALT) with selective laser trabeculoplasty (SLT) in terms of their efficiency in lowering the intra-ocular pressure.

In this retrospective study, 56 eyes from 44 patients with primary open angle glaucoma, ocular hypertension, pseudo-exfoliative (PXF) or pigment dispersion glaucoma (PDG) were included. Patients underwent either ALT (n=18) or SLT (n=38). The intraocular pressure (IOP) was measured immediately prior to and 3 to 5 weeks after the theraPY.

At 3 to 5 weeks the lOP-reduction was 22.4% after ALT and 15.5% after SLT (p = 0.141). Of note, of the four patients with PDG 2 underwent ALT and 2 SLT. Remarkably, both patients who had had SLT showed a paradoxical rise in lOP after the procedure (+15.5%). When these patients were excluded from the analysis, a similar hypotensive efficacy was found between ALT (-19%) and SLT (-17.9%) (p = 0.836). A small additional study with lower energy levels (< 0.9 mJ) confirmed the paradoxical IOP rise in 6 patients with heavily pigmented angles (2 with PDG and 2 with PXF) (+19.2%). It occurred in the absence of steroid treatment and persisted until 12 weeks after treatment.

The short term efficacy of ALT and SLT was similar. In this study, the patients with PDG who underwent SLT showed a paradoxical rise in IOR This finding may indicate that even lower energies (0.4 to 0.6 mJ) are required when performing SLT in patients with heavily pigmented trabeculae.