Five-year outcomes of selective laser trabeculoplasty: A retrospective study

Abstract

Introduction: Studies have shown the efficacy of selective laser trabeculoplasty (SLT) to lower intraocular pressure (IOP) as adjuvant therapy during short-term follow-up. However, few studies have assessed the long-term efficacy of SLT on preventing worsening Humphrey visual field (HVF) parameters and thinning of the retinal nerve fiber layer (RNFL) with continued medical therapy.

Methods: A retrospective chart review was conducted of 51 eyes of 39 patients with glaucoma treated with SLT at Boston Medical Center between 2012 and 2016 with 3- and 5-year follow-up. Outcome measures included IOP, visual acuity, number of glaucoma medications, number of months to subsequent surgical intervention. HVF outcome measures included mean deviation (MD) and pattern standard deviation (PSD). Optical coherence tomography (OCT) outcome measures included RNFL mean thickness, and superior and inferior thicknesses.

Results: Twenty-five eyes received subsequent surgical intervention (mean time to intervention = 33.6 ± 20.0 months). In the eyes that did not receive another intervention, mean IOP was significantly decreased by 3.2 and 3.5 mmHg at 3- and 5-year after SLT, respectively. Mean number of glaucoma medications was significantly increased at 5-year (2.7 ± 1.6; P = 0.04), compared to pre-SLT (2.0 ± 1.1). Mean HVF MD was significantly higher at 5-year (-7.64 ± 6.57 dB) compared to pre-SLT (-5.61 ± 3.90 dB). Mean PSD significantly increased at 3-year (5.30 ± 2.91 dB) and 5-year (6.84 ± 2.62 dB), compared to pre-SLT (4.63 ± 2.70 dB; P = 0.04 and ≤0.01, respectively). On OCT, inferior quadrant RNFL thickness decreased significantly at 5-year (88.5 ± 19.3 μm), compared to pre-SLT (94.0 ± 23.2 μm).

Discussion: Although 51% of eyes had IOP controlled at 5-year post-SLT, mean number of glaucoma medications was significantly higher. Also, there was progression of MD and PSD on HVF and inferior quadrant thinning on OCT at 5-year. We found a significant association between age at SLT and risk of subsequent surgical intervention over 5-year follow-up. Our study adds to our understanding of long-term outcomes of adjuvant SLT for glaucoma patients receiving medical therapy.

Keywords: glaucoma; intraocular pressure; optical coherence tomography; retinal nerve fiber thickness; retrospective chart review; selective laser trabeculoplasty.

FIGURE 1

CONSORT diagram for retrospective chart review. We retrospectively screened 439 charts of eyes with diagnosis of glaucoma that received SLT at Boston Medical Center from 2012 to 2016. We excluded 388 eyes that had a previous laser procedure, were lost to follow-up within 5-year, or had secondary open-angle glaucoma or angle-closure glaucoma. We included 51 eyes, who had sufficient 5-year follow-up, of which 25 received subsequent surgical intervention and 26 did not. For analysis of the outcome measures of the patients that did not receive subsequent surgical intervention, we excluded fellow eyes to only analyze one eye per patient.

FIGURE 2

Cox proportional hazard survival curve for time to subsequent surgical intervention. Survival analysis showed a 79.6% survival probability at 36 months and a 60.7% survival probability at 60 months. Dotted lines represent upper and lower 95% confidence intervals.