Titanium-Sapphire Laser Trabeculoplasty in the Treatment of Open-Angle Glaucoma

Abstract

Laser trabeculoplasty is accepted as an effective treatment in patients with open-angle glaucoma. Success rates of 30% IOP reduction have been reported although the effect may be temporary.1-4 There are several types of lasers currently used in glaucoma treatment including argon, diode, krypton and neodymium:YAG.2,5-11 Argon laser trabeculoplasty (ALT) is, by far, the most commonly used treatment, but may be associated with early anterior chamber reaction, local irritation, peripheral anterior synechia (PAS) formation and IOP spikes.6,9,11 Argon laser trabeculoplasty is thought to lower IOP by triggering a biological response within the trabecular meshwork (TM). However, scarring of the trabecular meshwork that is associated with ALT limits its effectiveness in subsequent applications. 6,11-14 As a result of this limitation of ALT, selective laser trabeculoplasty (SLT) was developed as a gentler method of IOP reduction without the unnecessary scarring of the trabecular meshwork. Selective laser trabeculoplasty (SLT) utilizes a frequencydoubled neodymium:YAG laser (Nd:YAG SLT) and has been shown to be at least as effective as ALT but with less ocular inflammation and fewer IOP spikes after treatment.1,3,15-19 The lack of trabecular scarring after SLT may allow repeated treatments in patients with previous ALT. We present a third treatment option, Titanium-Sapphire laser trabeculoplasty (TiSLT) that was developed in attempt to improve the efficacy of laser therapy of the trabecular meshwork (Fig. 1). The physical parameters of the Ti-Sapphire laser are: a wavelength of 790 nm; exposure time of 7 mSec, and a spot size of 200 microns. (Figs 2 and 3) Such infrared wavelength is associated with deeper penetration into the TM, affecting tissues like juxta-canalicular region and inner wall of Schlemm’s canal (SC) (Fig. 4). An in vivo study comparing the histology of 3 different lasers (ALT, SLT and TiSLT) in an enucleated human eye confirmed that TiSLT penetrates deeper with disruption of inner wall of Schlemm’s canal (Presented at the unpublished Fig. 1: SOLX 790 laser machine