Deep sclerectomy was developed to avoid the intraoperative and postoperative complications seen with trabeculectomy.Compared to trabeculectomy, the anterior chamber is not opened in deep sclerectomy. In addition to a superficial scleral flap as performed in trabeculectomy, a second deep scleral flap is created directly beneath the first flap so that the external part of Schlemm's canal is opened and corneal tissue removed leaving only Descemet's membrane separating the anterior chamber. Various implants serve to delay or avoid formation of scar tissue. In cases of insufficient reduction of intraocular pressure (IOP) Descemet's membrane can be finely perforated by an additional goniopuncture leading to better drainage of the aqueous humor.There is a controversial discussion about the pressure lowering effect of deep sclerectomy in comparison to trabeculectomy. Some studies have shown a similar long-term efficacy for both procedures but others showed an advantage for trabeculectomy. As expected, the complication rate could be clearly reduced with deep sclerectomy. Deep sclerectomy therefore represents a safe alternative to trabeculectomy.