Novel Surgical Techniques to Control Flow With PreserFlo MicroShunt for Late Hypotony After Baerveldt Drainage Device Implantation.

We report a new surgical technique for controlling flow with a PreserFlo MicroShunt, in patients with late postoperative hypotony, following a Baerveldt glaucoma drainage device implantation. We present 2 cases with late postoperative hypotony after Baerveldt-shunt implantations. In both cases, the outflow resistance of the Baerveldt tube was modulated by the insertion of a PreserFlo MicroShunt into the lumen of the Baerveldt tube. In the first case, the Microshunt was inserted through the distal opening of the tube in the anterior chamber. In the second case, an end plate, sided approach was chosen after opening the conjunctiva. In both cases, the hypotony was successfully treated. The intraocular pressure rose immediately after the procedure, and it remained well controlled within the targeted range during the first postoperative months without additional pressure-lowering medication. This novel surgical technique provided predictable flow reductions, according to the Hagen-Poiseuille equation. This approach offers a valuable alternative to permanent tube ligation.