Selective Laser Trabeculoplasty Protects Glaucoma Progression in the Initial Primary Open-Angle Glaucoma and Angle-Closure Glaucoma after Laser Peripheral Iridotomy in the Long Term

Abstract

Purpose. To compare the ability of SLT in preventing glaucoma progression in the initial primary angle-closure glaucoma (PACG) after laser peripheral iridotomy and primary open-angle glaucoma (POAG) in the long term. Methods. 60 patients with the initial stage of PACG after laser peripheral iridotomy and 64 initial POAG patients were recruited in a prospective study. Complete success of selective laser trabeculoplasty (SLT) was defined as a 20% intraocular pressure (IOP) reduction with topical hypotensive medications without any hypotensive intervention. Pre-SLT rate of progression and post-SLT rate of progression (ROP) was detected in the both groups by means of the trend and the event analysis of perimetry, the Guided Progression Analysis, and the optical coherence tomography- (OCT-) based negative trend for either the thickness of the peripapillary retinal nerve fiber layer (RNFL) or ganglion cell complex (GCC). Results. IOP decreased significantly after SLT in both the groups. 30% in PACG and 19% in POAG had the progression according to perimetry and 49% in PACG and 40% in POAG had the progression, respectively, according to OCT. After SLT, ROP was reduced from -0.14 ± 0.39 dB/year to -0.08 ± 0.48 dB/year, p=0.034, in PACG and from -0.09 ± 0.36 dB/year to -0.04 ± 0.43 dB/year, p=0.021, in POAG. According to RNFL trend analysis, ROP was reduced from -1.86 ± 2.9 μm/year to -1.38 ± 2.2 μm/year, p=0.039, and from -1.24 ± 2.23 μm/year to -0.76 ± 1.73 μm/year, p=0.037, in PACG and POAG, and according to GCC, ROP was reduced from -1.88 ± 2.9 μm/year to -1.34 ± 2.0 μm/year, p=0.040, and from -1.35 ± 2.16 μm/year to -0.91 ± 1.86 μm/year, p=0.040, in PACG and POAG, respectively. ROP was significantly faster in PACD than in POAG between 2 and 6 years after SLT: -0.15 ± 0.46 dB/year and 0.02 ± 0.38 dB/year (p=0.042). However, it did not differ significantly according to OCT. Conclusion. SLT is an effective treatment for initial PACG after LPI and POAG that can prevent functional and structural deterioration in the long term.