Laser sclerostomy ab externo using the erbium: YAG laser. First results of a clinical study

A new approach to fistulating glaucoma surgery, laser sclerostomy ab externo, was investigated in a clinical study. A pulsed (200 microseconds) erbium-YAG laser was used, as its wavelength (2940 nm) is very well absorbed by tissue water. The laser energy was transmitted via a fiber to an application probe with a cannula particularly designed to guide another fiber into the subconjunctival space. Nine patients with advanced open-angle or neovascular glaucoma were treated. In all cases a functioning fistula with a prominent filtering bleb and a reduction of the intraocular pressure (from up to 50 mmHg to 8-18 mmHg) could be achieved. The total energy was 60 mJ on average. No complication occurred intraoperatively. Postoperatively, all fistulas in patients with neovascular glaucoma (n = 6) were impatent after approx. 7 days due to iris adherence to the internal ostium and episcleral scarring. In cases of open-angle glaucoma (n = 3) a patent fistula persisted for several months. Variation of the exposure parameters, the use of antiproliferative drugs, and a less restrictive selection of patients could further improve the success rate.