[Progress in laser sclerotomy ab externo] Enlarging the sclerostomy channel and local mitomycin administration].

In a previous study we presented our first results after sclerostomy using a pulsed erbium/holmium: YAG laser. At a fiber diameter of 300 microns a success rate of 20-30% was found after a 1-year follow-up. This study concentrates on the improvement of the parameters for filter survival. METHODS. The fiber diameter and thus the size of the fistula increased to 400 microns. Patients who had undergone fibrosis for a previous fistula were treated intraoperatively with topical mitomycin administration. RESULTS. After a follow-up of 6 months, filter function in the 300 microns group was maintained in 26% of the treated eyes (n = 23), while 400 microns fistulas were successful in 48% (n = 26). In the mitomycin-treated group (n = 6), sclerostomy achieved an IOP regulation in four patients. Postoperative hypotony was more frequent, but did not exceed 2 weeks. CONCLUSION. An increase in fistula diameter improves the long-term results of laser sclerostomy. Mitomycin is useful in maintaining filter function in patients with an unfavorable prognosis.