Efficacy of Selective Laser Trabeculoplasty after iStent Implantation in Primary Open-Angle Glaucoma.

Adam R Siedlecki,Patrice M Hicks,Benjamin Haaland,Margaret M Deangelis,Sandra F Sieminski

doi:10.3390/jpm11080797

Abstract

iStent implantation is thought to augment the trabecular outflow channel in the anterior segment of the eye. We hypothesized that iStent with subsequent selective laser trabeculoplasty (SLT) would better control the intraocular pressure (IOP) compared to standalone SLT in patients with primary open-angle glaucoma (POAG). We, therefore, determined if the presence of an iStent combined with SLT was statistically associated with IOP lowering compared to standalone SLT. Through retrospective electronic medical record review, records of 824 eyes from 440 patients who received primary SLT without a history of iStent were considered. Additionally, 42 eyes from 28 patients who received SLT after combined phacoemulsification and iStent implantation that failed to control intraocular pressure (IOP) and/or the progression of the disease were retrospectively reviewed. IOP and number of medications, which were tracked in each patient for up to 12 months post laser, were also examined. Successful outcome was defined as a statistically significant reduction in IOP or number of medications at 6 months. As defined in univariate analysis (p ≤ 0.01), multivariate analysis included iStent, age, sex, race, and initial IOP as variables. IOP reduction was statistically associated with patients pre-SLT IOP (p < 0.001) but not with patients with iStent (p = 0.222). Medication reduction was statistically associated with the pre-SLT number of medications (p < 0.001) and iStent (p < 0.001). In eyes that received SLT, iStent was not statistically associated with a greater reduction in IOP compared to controls, but was associated with a higher reduction in the overall number of medications used 6 months after receiving SLT. The work presented should guide clinicians to consider SLT as an effective therapy after iStent implantation, in terms of glaucoma medication reduction in iStent patients, but clinicians should know that the presence of an iStent does not necessarily make subsequent SLT more effective at lowering IOP.

Highlights

The purpose of this study is to investigate the efficacy of selective laser trabeculoplasty (SLT) after combined phacoemulsification and iStent implantation failed to control the intraocular pressure (IOP) and/or progression of glaucoma
While our data analysis showed that iStent was not statistically associated with a reduction in IOP in primary open-angle glaucoma (POAG) patients who receive SLT, our data support that history of prior phacoemulsification and iStent implantation is associated with a statistically significant reduction of the number of medications post-SLT compared to control patients
This study found that the cumulative rate of success of SLT after failed trabeculectomy was 16% at 12 months post laser

Summary

Introduction

Glaucoma is a heterogeneous group of eye diseases associated with intraocular pressure and optic nerve damage, resulting in characteristic visual field loss patterns and eventual blindness if untreated [1]. It is the leading cause of blindness worldwide [2]. Glaucoma is subdivided into primary versus secondary causes and open versus closed angles. Primary open-angle glaucoma is a chronic, progressive form of glaucoma characterized by gradual loss of retinal ganglion cells and optic nerve atrophy [3]. Increased IOP is a significant risk factor associated with the development and progression of glaucomatous damage to the optic nerve, resulting in blindness [3,4]. Controlling IOP is a mainstay of clinical and surgical management for glaucoma patients, even for patients whose IOP is in the normal range [5]

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