 However, NPDS is performed manually and requires higher level of skills that may be assisted with instruments.In order to prevent wound adhesion after deep scleral excision and to maintain good filtering results, NPDS as with other non-penetrating procedures is sometimes performed with a variety of biocompatible spacers or devices, such as the Aquaflow collagen wick, ologen Collagen Matrix, or Xenoplast glaucoma implant.Laser-assisted NPDS is performed with the use of a CO2 laser system.