title: Choroidal expansion during the water drinking test.
abstract: OBJECTIVE
  To evaluate the correlation between intraocular pressure (IOP) rise, ocular pulse amplitude (OPA), and choroidal thickness (ChT) during the water drinking test (WDT).
  
  
  METHODS
  Primary open-angle glaucoma (POAG) patients were submitted to the WDT followed by serial IOP measurements using dynamic contour tonometry (DCT), Goldman tonometry (GAT), and ChT measurements using ultrasonographic A and B-scan (USG). A control group not submitted to the test was also evaluated using DCT, GAT, and USG. Intraclass correlation coefficient (ICC) was calculated in the control group in order to assess the reproducibility of measurements. Spearman's coefficient (rho) was used to assess the correlation between the variables.
  
  
  RESULTS
  Thirty eyes were included in the study. There was a significant IOP rise during the WDT using both GAT and DCT (p < 0.001). The OPA and ChT measurements also increased significantly (p < 0.001). Spearman's correlation between the OPA values and ChT measurements was significant and moderate (rho = 0.40, p = 0.005). The average increase of OPA and ChT measurements occurred 15 min before the IOP rise.
  
  
  CONCLUSIONS
  There was a significant increase of OPA and ChT measurements followed by an IOP rise during the WDT. Increased choroidal volume due to hemodynamic forces may be enrolled in the mechanism of IOP elevation during this stress test.
authors.affiliation: Glaucoma Service, Department of Ophthalmology, University of Sao Paulo School of Medicine, Sao Paulo, SP, Brazil. gustavousp@gmail.com
authors.forename: Carlos Gustavo Vasconcelos
authors.initials: CG
authors.lastname: De Moraes
authors.forename: Alexandre Soares Castro
authors.initials: AS
authors.lastname: Reis
authors.forename: Adhele Furlani de Sá
authors.initials: AF
authors.lastname: Cavalcante
authors.forename: Milena Eimi
authors.initials: ME
authors.lastname: Sano
authors.forename: Remo
authors.initials: R
authors.lastname: Susanna
mesh_terms: D001794:Blood Pressure; D002829:Choroid / Q000000981:diagnostic imaging / Q000503:physiopathology*; D003941:Diagnostic Techniques, Ophthalmological; D004326:Drinking; D005260:Female; D005902:Glaucoma, Open-Angle / Q000503:physiopathology*; D006801:Humans; D007429:Intraocular Pressure / Q000502:physiology*; D008297:Male; D008875:Middle Aged; D009798:Ocular Hypertension / Q000503:physiopathology; D014065:Tonometry, Ocular; D014463:Ultrasonography; D014867:Water
chemical_list: D014867:Water