title: Assessment of Filtration Bleb and Endplate Positioning Using Magnetic Resonance Imaging in Eyes Implanted with Long-Tube Glaucoma Drainage Devices.
abstract: BACKGROUND
  To evaluate ocular fluid filtration and endplate positioning in glaucomatous eyes with long-tube glaucoma drainage devices (GDDs) using magnetic resonance imaging (MRI) and the effects of various factors on postoperative intraocular pressure (IOP).
  
  
  METHODS
  This observational case series included 27 consecutive glaucomatous eyes (18 men, 7 women; mean age ± standard error, 63.0±2.0 years) who underwent GDD implantation (n = 8 Ahmed Glaucoma Valves [AGV] and n = 19 Baerveldt Glaucoma Implants [BGI]). Tubes were inserted into the pars plana in 23 eyes and anterior chamber in 4 eyes. Six months postoperatively, high-resolution orbital images were obtained using 3-Tesla MRI with head-array coils, and the filtering bleb volume, bleb height, and distances between the anterior endplate edge and corneal center or limbus or between the endplate and orbital wall were measured.
  
  
  RESULTS
  In MR images obtained by three-dimensional fast imaging employing steady-state acquisition (3D-FIESTA) sequences, the shunt endplate was identified as low-intensity signal, and the filtering bleb was identified as high-intensity signals above and below the endplate in all eyes. The 6-month-postoperative IOP level was correlated negatively with bleb volume (r = -0.4510, P = 0.0182) and bleb height (r = -0.3954, P = 0.0412). The postoperative IOP was significantly (P = 0.0026) lower in BGI-implanted eyes (12.2±0.7 mmHg) than AGV-implanted eyes (16.7±1.2 mmHg); bleb volume was significantly (P = 0.0093) larger in BGI-implanted eyes (478.8±84.2 mm3) than AGV-implanted eyes (161.1±52.3 mm3). Other parameters did not differ.
  
  
  CONCLUSIONS
  The presence of intraorbital/periocular accumulation of ocular fluid affects postoperative IOP levels in eyes implanted with long-tube GDDs. Larger filtering blebs after BGI than AGI implantations explain lower postoperative IOP levels achieved with BGI than AGV. The findings will contribute to better understanding of IOP reducing mechanism of long-tube GDDs.
authors.affiliation: Division of Ophthalmology, Matsue Red Cross Hospital, Matsue, Japan.|Department of Ophthalmology, Shimane University Faculty of Medicine, Izumo, Japan.
authors.forename: Ichiya
authors.initials: I
authors.lastname: Sano
authors.affiliation: Division of Ophthalmology, Matsue Red Cross Hospital, Matsue, Japan.|Department of Ophthalmology, Shimane University Faculty of Medicine, Izumo, Japan.
authors.forename: Masaki
authors.initials: M
authors.lastname: Tanito
authors.affiliation: Department of Radiology, Shimane University Faculty of Medicine, Izumo, Japan.
authors.forename: Koji
authors.initials: K
authors.lastname: Uchida
authors.affiliation: Department of Radiology, Shimane University Faculty of Medicine, Izumo, Japan.
authors.forename: Takashi
authors.initials: T
authors.lastname: Katsube
authors.affiliation: Department of Radiology, Shimane University Faculty of Medicine, Izumo, Japan.
authors.forename: Hajime
authors.initials: H
authors.lastname: Kitagaki
authors.affiliation: Department of Ophthalmology, Shimane University Faculty of Medicine, Izumo, Japan.
authors.forename: Akihiro
authors.initials: A
authors.lastname: Ohira
mesh_terms: D000328:Adult; D000368:Aged; D001768:Blister / Q000503:physiopathology / Q000601:surgery*; D004322:Drainage; D005260:Female; D005901:Glaucoma / Q000503:physiopathology / Q000601:surgery*; D020327:Glaucoma Drainage Implants; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods; D007429:Intraocular Pressure / Q000502:physiology; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D056888:Patient Positioning; D019919:Prosthesis Implantation; D014792:Visual Acuity