Ab interno infrared laser trabecular ablation: preliminary short-term results in patients with open-angle glaucoma

Outflow obstruction of trabecular drainage structures results in elevation of intraocular pressure (IOP) in various forms of chronic open-angle glaucoma. In vitro studies have shown that laser trabecular ablation (LTA) with opening of Schlemm's canal can be reproducibly performed by use of infrared lasers with minimal damage to collateral tissue structures.

In order to investigate the clinical applicability and efficacy of ab interno contact laser photoablation of trabecular meshwork in the surgical treatment of human glaucoma, we conducted a pilot study using an erbium: YAG laser (2.94 microns) with a quartz fiber endoprobe (320 microns core diameter) applying 10-20 single laser pulses (5-7 mJ) to the trabecular meshwork.

Under goniocopic visualization trabecular tissue was photovaporized in eight patients with primary or secondary chronic open-angle glaucoma. Intraoperatively, moderate reflux bleeding occurred from laser-induced craters. No major intra- or postoperative complications occurred. Preoperative and postoperative gonioscopy of the treated area demonstrated successful removal of trabecular tissue. Mean IOP was reduced from 36.1 mmHg ot 21.3 mmHg at a limited follow-up of 3 months.

With modifications this technique may have clinical potential in the surgical management of glaucoma. Prospective long-term studies with more patients are warranted to evaluate the outcome of LTA.