[Revision surgery in episcleral glaucoma drainage devices].

Episcleral glaucoma drainage devices (e.g., Ahmed or Baerveldt drainage device) are often used at a late stage in the care of glaucoma patients. At this stage other surgical techniques, such as trabeculectomy or viscocanaloplasty, have failed. However, the trend towards earlier implant surgery is supported by large randomized trials. Physicians should be aware of typical complications and, if possible, these should already be avoided by careful surgical technique. In this review article, we focus on postoperative hypotension, postoperative pressure increases, implant exposure, and possible corneal decompensation.