Mini Drainage Devices for Anterior and Intermediate Filtration.

Mini glaucoma devices for external filtration may be implanted with an ab externo procedure (Ex-PRESS and InnFocus Microshunt) or with an ab interno procedure (XEN Gel stent). The Ex-PRESS is an FDA-approved mini glaucoma device that has been developed in order to simplify anterior guarded filtering procedures, making them faster, safer and easier. It is positioned under a scleral flap and it is introduced in the anterior chamber through a needle hole, avoiding the excision of the corneal-scleral button and the iridectomy. Like other anterior filtering guarded procedures, it may be associated with releasable sutures and with an everting suture (the safe Ex-PRESS procedure) in order to increase safety and efficacy. The InnFocus Microshunt is a new ab externo filtering device currently under investigation; it is very easy to implant and highly promising in terms of safety and efficacy. The XEN Gel stent is an ab interno implanted soft, collagen tube that makes a permanent bypass between the anterior chamber and the subconjunctival space. It is a smart, quick, effective and simple procedure that recently gained FDA approval.