Micropulse laser trabeculoplasty under maximal tolerable glaucoma eyedrops: treatment effectiveness and impact of surgical expertise

Abstract

AIM: To evaluate the effectiveness of micropulse laser trabeculoplasty (MLT) for eyes with open angle glaucoma (OAG) under maximal tolerable glaucoma eyedrops and to assess the effect of expertise performing MLT on its clinical effectiveness. METHODS: Medical records of 42 consecutive eyes of 34 patients diagnosed with OAG who underwent MLT were retrospectively reviewed. The effectiveness was determined using the Kaplan-Meier survival analysis. Failure was defined as an intraocular pressure (IOP) reduction of <20% from baseline, an IOP >21 mm Hg during two consecutive follow-up visits, or surgical intervention for OAG. To determine the impact of MLT surgical expertise on clinical effectiveness, the eyes were divided into two groups according to whether the procedure was conducted by an experienced specialist (defined as a glaucoma specialist who had conducted at least ten MLT procedures) or a less experienced glaucoma specialist. The difference in expertise was determined using a log-rank test. RESULTS: MLT was conducted by three glaucoma specialists. The overall survival rates were 0.76, 0.48, and 0.44 at 1, 3, and 6mo, respectively. The survival rates for MLT performed by a less experienced glaucoma specialist were 0.62, 0.31, and 0.25 (n=21 eyes) at 1, 3, and 6mo, respectively, whereas the survival rates for MLT performed by an experienced glaucoma specialist were 0.90, 0.64, and 0.64 (n=21 eyes) at 1, 3, and 6mo, respectively. The log-rank test showed a significant difference in the survival curves of the two groups (P=0.0061). CONCLUSION: The 6-month effectiveness of MLT for controlling IOP is relatively limited in eyes with OAG using maximal tolerable glaucoma eyedrops. However, its effectiveness may be improved if performed by a glaucoma specialist with sufficient MLT experience.

Spotlight on MicroPulse Laser Trabeculoplasty in Open-Angle Glaucoma: What’s on? A Review of the Literature

“…In more recent times, the 577- or 532-nm MDLT approaches over 360° of TM were reported to be successful alternatives to classic laser trabeculoplasty procedures for lowering IOP and decreasing the amount of anti-hypertensive drugs, particularly in individuals with primary open-angle glaucoma. Several studies claimed success rates ranging from 37% to 44%, with final post-operative IOPs from 12.8 to 16.7 mmHg in mid- or long-term follow-ups [ 26 , 27 , 28 , 29 , 54 , 58 , 59 , 60 , 61 ]. Along with an average IOP reduction varying from 7.2% to 21.6%, MDLT was also shown to have no major or long-term side effects in the analyzed research, highlighting its capacity to limit post-procedural IOP spikes or intra-ocular inflammation [ 26 , 27 , 28 , 29 , 54 , 58 , 59 , 60 , 61 ].…”

“…Several studies claimed success rates ranging from 37% to 44%, with final post-operative IOPs from 12.8 to 16.7 mmHg in mid- or long-term follow-ups [ 26 , 27 , 28 , 29 , 54 , 58 , 59 , 60 , 61 ]. Along with an average IOP reduction varying from 7.2% to 21.6%, MDLT was also shown to have no major or long-term side effects in the analyzed research, highlighting its capacity to limit post-procedural IOP spikes or intra-ocular inflammation [ 26 , 27 , 28 , 29 , 54 , 58 , 59 , 60 , 61 ]. Moreover, intra-procedural pain was reported to be significantly lower with the MDLT, rather than the SLT approach [ 28 ].…”

“…Since its introduction, different researchers tried to optimize laser settings and geographical objectives. The classical 810-nm diode laser MDLT approach, claimed in the first years by many investigators, [ 21 , 22 , 23 , 24 ] recently gave way to new approaches with 532- or 577-nm diode laser [ 26 , 27 , 28 , 29 , 54 , 58 , 59 , 60 , 61 ]. The settings for both the 577-nm yellow laser (IRIDEX Corporation, Mountain View, CA, USA) and the 532-nm green laser (IRIDEX Corporation, Mountain View, CA, USA) were generally repeated among researchers, with 1000 mW of power, 300 ms duration, 300 μm spot size, and a 15% duty cycle.…”

“…Recently, a retrospective study by Kakihara et al focused on 577-nm MDLT treatment for OAG patients under maximal tolerable glaucoma eyedrops, to assess the survival rate after MDLT [ 61 ]. Failure was defined as a reduction <20% in IOP from baseline or >21 mm Hg during two consecutive follow-up visits or the need for surgical intervention.…”

“…The efficacy of MDLT in eyes with advanced glaucoma was shown to be restricted in this investigation, since the success rate at 6 months following surgery was only 44%. The authors hypothesized that the optimal MDLT approach may need a steeper learning curve, because higher survival rates were reported when MDLT procedure was carried out by a glaucoma specialist with sufficient MDLT experience [ 61 ].…”