[Role of Intraoperative Indirect Channelography in Glaucoma Stent Implantation]

Several glaucoma stents are available to surgically reduce the intraocular pressure in primary open-angle glaucoma (POAG). In comparison to conjunctival opening procedures, the advantages of microinvasive glaucoma surgery (MIGS) are relatively atraumatic ab-interno procedures through a paracentesis, conjunctival sparing for later filtrating surgery, and possible combined cataract surgery. In this overview, the principle of intraoperative indirect channelography as a decision criterion for the individual selection of glaucoma stent implantation is presented. Through a paracentesis a slight hypotony was induced and retrograde blood filling of Schlemm's canal was observed gonioscopically. Good blood filling was an indicator for an intact drainage system through the collector channels and the episcleral veins. In these patients a trabecular bypass stent system can be placed in Schlemm's canal of the anterior chamber angle to improve drainage of aqueous humour and reduce the intraocular pressure (IOP). In patients with a negative intraoperative indirect channelography, which can be recognized through an absent or insufficient retrograde blood filling of Schlemm's canal, an alternative drainage path should be considered by using supraciliary or subconjunctival glaucoma stents. A significant mean IOP reduction of 17 to 36% can be achieved with a reduction of local glaucoma therapy. Relevant complications with choroidal detachment and decreased visual acuity due to postoperative hypotony are rare.