title: Baerveldt drainage tube motility in the anterior chamber.
abstract: OBJECTIVE
  To investigate the stability in position of the Baerveldt glaucoma drainage tube over time and to study movement of the drainage tube in the anterior chamber (AC) under varying light conditions.
  
  
  METHODS
  This prospective study included 70 eyes with implantation of a Baerveldt glaucoma drainage tube in the anterior chamber. Anterior segment optical coherence tomography (AS-OCT) images were made preoperatively to quantify AC depth. AS-OCT images were made twice under photopic and twice under scotopic conditions, in the angle parallel to the Baerveldt tube to quantify drainage tube position, at 3, 6, 12, and 24 months postoperatively. Tube-corneal (T-C) and tube-iris (T-I) distances were measured. Additionally, the central AC depth and the peripheral angle opening (AOD 500) were determined. Two subgroups were distinguished according to tube position: free in the AC (group 1, n = 48) and transiridal (group 2, n = 22).
  
  
  RESULTS
  After 24 months of follow-up, the drainage tube was found to move statistically significantly closer (0.12 mm) to the corneal endothelium in group 1 (p<0.01). There was no statistically significant difference in T-C distance over time in group 2. The T-C distance did not differ under photopic versus scotopic circumstances (p = 0.32). In both groups, the T-I distance was larger under scotopic conditions, a result of pupil dilation.
  
  
  CONCLUSIONS
  The Baerveldt glaucoma drainage tube remained in a stable position when a transiridal implantation was performed, whereas the tube moved closer to the endothelium when placed free into the AC. Transiridal implantation of the Baerveldt tube seems a safe alternative for tube implantation with respect to tube motility.
authors.affiliation: 1 University Eye Clinic, Maastricht University Medical Center, Maastricht - the Netherlands.
authors.forename: Annelie N
authors.initials: AN
authors.lastname: Tan
authors.forename: Pauline M
authors.initials: PM
authors.lastname: De Witte
authors.forename: Carroll A B
authors.initials: CA
authors.lastname: Webers
authors.forename: Tos T J M
authors.initials: TT
authors.lastname: Berendschot
authors.forename: John
authors.initials: J
authors.lastname: De Brabander
authors.forename: Johannes S A G
authors.initials: JS
authors.lastname: Schouten
authors.forename: Henny J M
authors.initials: HJ
authors.lastname: Beckers
mesh_terms: D000328:Adult; D000867:Anterior Chamber / Q000601:surgery*; D004322:Drainage / Q000295:instrumentation*; D005260:Female; D005901:Glaucoma / Q000601:surgery*; D020327:Glaucoma Drainage Implants; D006801:Humans; D007498:Iris / Q000601:surgery; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D019919:Prosthesis Implantation / Q000379:methods*; D013536:Suture Techniques; D041623:Tomography, Optical Coherence / Q000379:methods