title: [Development of a glaucoma microstent with drainage into the suprachoroidal space: fluid mechanical model approach].
abstract: BACKGROUND
  The purpose of this study was to develop a microstent with valve function, which normalizes the intraocular pressure (IOP) and drains into the suprachoroidal space. In comparison to the subconjunctival space the suprachoroidal space is attributed with less fibroblast colonization and activity.
  
  
  METHODS
  Different glaucoma drainage devices were idealized as tubes and the flow rates were calculated according to Hagen-Poiseuille. The dimensions of the ideal glaucoma implant were modified with respect to an aqueous humor production of 2 microl/min and the different outflow pathways. Specific components of glaucoma drainage devices at the inlet and outlet were not included.
  
  
  RESULTS
  The volume flow calculation of the tested glaucoma implants showed that the dimensions of all lumina were too large to prevent postoperative hypotension. A maximum inner tube diameter of 53 microm was calculated for drainage into the suprachoroidal space based on an intra-ocular pressure (IOP) of 20 mmHg.
  
  
  CONCLUSIONS
  The glaucoma microstent has to guarantee an aqueous humor flow for physiological IOP. An increase of IOP has to be regulated to physiological pressure conditions by the microvalve.
authors.affiliation: Medizinische Fakultät, Klinik und Poliklinik für Augenheilkunde, Universität Rostock, 18057 Rostock. Rudolf.Guthoff@med.uni-rostock.de
authors.forename: R F
authors.initials: RF
authors.lastname: Guthoff
authors.forename: W
authors.initials: W
authors.lastname: Schmidt
authors.forename: D
authors.initials: D
authors.lastname: Buss
authors.forename: C
authors.initials: C
authors.lastname: Schultze
authors.forename: U
authors.initials: U
authors.lastname: Ruppin
authors.forename: O
authors.initials: O
authors.lastname: Stachs
authors.forename: K
authors.initials: K
authors.lastname: Sternberg
authors.forename: D
authors.initials: D
authors.lastname: Klee
authors.forename: B
authors.initials: B
authors.lastname: Chichkov
authors.forename: K-P
authors.initials: KP
authors.lastname: Schmitz
mesh_terms: D002829:Choroid / Q000601:surgery*; D003198:Computer Simulation; D004867:Equipment Design; D019544:Equipment Failure Analysis; D005901:Glaucoma / Q000601:surgery*; D020327:Glaucoma Drainage Implants; D006801:Humans; D044085:Microfluidics / Q000295:instrumentation* / Q000379:methods*; D008904:Miniaturization; D008962:Models, Theoretical; D015607:Stents