title: Magnetic Resonance Imaging Study on Blebs Morphology of Ahmed Valves.
abstract: OBJECTIVE
  To determine the morphometric parameters of filtration blebs of a valved aqueous humor drainage device.
  
  
  METHODS
  Orbital magnetic resonances imaging (MRI) was taken after implantation of an Ahmed valve (FP7 model). Outcomes of the analysis were intraocular pressure (IOP) and the bleb's morphometric analysis (volume, height, major and minor axis). Associations between IOP and the imaging-related study variables were explored by Spearman's correlation test.
  
  
  RESULTS
  Eleven patients underwent orbital MRI examination. Recordings were taken after a mean of 2.7 months (1-6 months) after surgery. IOP was significantly lower than its preoperative values (17.6 ± 6.4 mm Hg vs 36.1 ± 6.4 mm Hg, p < 0.01). Mean bleb volume was 856.9 ± 261 mm(3) and its height, major and minor axis were 5.77 ± 1.9, 14.8 ± 2.9 and 8.14 ± 3.6 mm, respectively. A positive correlation was detected between IOP and mean height (r = 0.77, p = 0.048) and major axis (r = 0.83, p = 0.03). Interestingly, the overall bleb volume was related to IOP levels immediately prior to surgery (r = 0.75, p < 0.01). Additionally, the posterior part of the plate was found to be displaced from the scleral surface in five cases (45%).
  
  
  CONCLUSIONS
  Ahmed valve's bleb morphology seems to correlate with both the pre- and postoperative IOP, which might suggest a clinical benefit of administering aqueous suppressants pre- as well as postoperatively. The plate of the device may show a significant dislocation from its initial surgical implantation site. How to cite this article: Ferreira J, Fernandes F, Patricio M, Brás A, Rios C, Stalmans I, Pinto LA. Magnetic Resonance Imaging Study on Blebs Morphology of Ahmed Valves. J Curr Glaucoma Pract 2015;9(1):1-5.
authors.affiliation: Consultant, Department of Ophthalmology, Lisbon's Hospitals, Central Lisbon, Portugal.
authors.forename: Joana
authors.initials: J
authors.lastname: Ferreira
authors.affiliation: Consultant, Department of Ophthalmology, Lisbon's Hospitals, Central Lisbon, Portugal.
authors.forename: Fernando
authors.initials: F
authors.lastname: Fernandes
authors.affiliation: Consultant, Department of Neuroradiology, Lisbon's Hospitals, Central Lisbon, Portugal.
authors.forename: Madalena
authors.initials: M
authors.lastname: Patricio
authors.affiliation: Consultant, Department of Neuroradiology, Lisbon's Hospitals, Central Lisbon, Portugal.
authors.forename: Ana
authors.initials: A
authors.lastname: Brás
authors.affiliation: Consultant, Department of Neuroradiology, Lisbon's Hospitals, Central Lisbon, Portugal.
authors.forename: Cristina
authors.initials: C
authors.lastname: Rios
authors.affiliation: Professor, Department of Ophthalmology, University Hospitals, Leuven Belgium.
authors.forename: Ingeborg
authors.initials: I
authors.lastname: Stalmans
authors.affiliation: Consultant, Department of Ophthalmology, Lisbon's Hospitals, Central Lisbon, Portugal.
authors.forename: Luis Abegão
authors.initials: LA
authors.lastname: Pinto
keywords: Ahmed valve; Bleb morphology; Glaucoma; Intraocular pressure; Magnetic resonance imaging.