Date of Award

8-2-2010

Document Type

Thesis

Degree Name

Medical Doctor (MD)

First Advisor

Jimmy Zhou, PhD,

Second Advisor

M. Bruce Shields, MD

Third Advisor

Hylton Mayer, MD, Nils Loewen, MD

Abstract

REPEAT SELECTIVE LASER TRABECULOPLASTY IN THE TREATMENT OF OPEN-ANGLE GLAUCOMA. Bryan Kun Hong, Jeffrey C. Winer, James F. Martone, Martin Wand, Bruce Altman, M. Bruce Shields. Department of Ophthalmology, Yale University School of Medicine, New Haven, CT; Bryan Kun Hong, Sheila Mahdaviani, Brian A. Francis, Vikas Chopra, Laurie Dustin. Doheny Eye Institute, Keck School of Medicine, University of Southern California, Los Angeles, CA. (Sponsored by M. Bruce Shields, Department of Ophthalmology, Yale University School of Medicine) Purpose: To evaluate the efficacy of repeat 360-degree selective laser trabeculoplasty (SLT) in glaucoma patients with prior 360-degree SLT. Methods: Two studies were conducted - one at each of two institutions. Yale: 44 eyes of 35 patients, ≥18 years of age, with open-angle glaucoma (primary open-angle, pseudoexfoliation, or pigmentary glaucoma), uncontrolled on maximum tolerable medical therapy, underwent an initial 360-degree SLT (SLT1), which was successful for ≥6 months, but eventually lost efficacy and was followed by a repeat 360-degree SLT (SLT2). Patients with prior argon laser trabeculoplasty or other glaucoma surgery, before or during the study period, were excluded. Intraocular pressure (IOP) measurements were recorded before each SLT and at 1-4 weeks, 1-3 months, and 5-8 months after each SLT and 15-21 months post-SLT1. Doheny: 54 eyes of 42 patients were included. Protocol differed slightly from the Yale study in that patients with argon laser trabeculoplasty > 1 year prior to SLT1 were included, follow-up was more discrete (1, 3, 6, 12 months after each SLT), and an additional subanalysis was performed. Intersecting data points from both arms of the study were then combined and re-analyzed. Results: In the Yale study, reduction in IOP after SLT1 and SLT2 was significantly less with repeat treatment at 1 to 3 months, with average decreases of -5.0 and -2.9mm Hg, respectively (P=0.01), but there were no statistically significant differences at the other equivalent time points. Defining "success" as ≥20% peak IOP reduction, success rates for SLT1 and SLT2 were not significantly different. There was also no significant difference in eyes that received SLT2 6 to 12 months after SLT1 compared with those that received SLT2 12 months or more after SLT1. In the Doheny study, pooled SLT1 and SLT2 mean IOP baselines were significantly different, 19.7±4.4 versus 18.0±2.9 mmHg (p=0.009); however, the mean IOPs at each of the equivalent follow-up time points were not significantly different throughout follow-up, ranging from 16.0 to 16.6 mmHg, with the greatest decreases in IOP and medications observed at the post-SLT1 1-month time point. Subanalyses revealed that eyes that experienced a rise in IOP followed by reduction of IOP < 20% from baseline IOP after SLT1 were less responsive to repeat SLT and were accompanied by a gradual increase in medications that approximated pretreatment levels. Although there were no statistically significant differences between the lowest IOPs reached after both treatments, post-SLT2 IOPs rarely achieved levels lower than with SLT1. Conclusions: Repeat application of 360-degree SLT in eyes previously successfully treated with 360-degree SLT effectively lowers IOP in open-angle glaucoma to levels that are comparable to those seen after initial treatment with concomitant reduction in glaucoma medications after ≥ 12 month follow-up. This is not true for eyes that experience IOP rise above SLT1 baselines during early follow-up.

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