title: Clinical evaluation of the new TGDc-01 "PRA" palpebral tonometer: comparison with contact and non-contact tonometry.
abstract: OBJECTIVE
  The TGDc-01 "PRA" (Ryazan State Instrument, Ryazan, Russia) tonometer is a new portable small-sized tonometer that measures intraocular pressure (IOP) through the eyelid. The purpose of this study is to assess the repeatability of the TGDc-01 IOP measurements by comparing them against those obtained with Goldmann tonometer and with those from Perkins applanation tonometer, Xpert (Reichert, Depew, NY) noncontact tonometer, and Tono-Pen XL (Medtronic Solan, Jacksonville, FL) digital tonometer.
  
  
  METHODS
  Fifty-eight right eyes of 58 young subjects were measured with each of the tonometers. Noncontact tonometry was performed first, followed by Goldmann and Perkins applanation tonometer (in random order), digital Tono-Pen XL, and finally TGDc-01 tonometer (sitting and supine position). Correlation analysis was used to evaluate the relationship between the Goldmann tonometer and the remaining tonometers used in this study. Plotting the difference between the methods against mean was also done to compare the tonometers. The hypothesis of zero bias was examined by a paired t-test. The 95% limits of agreement (LoA) were also calculated.
  
  
  RESULTS
  TGDc-01 showed no statistical difference between the IOP measurements obtained in sitting and supine positions. A poor relationship between the TGDc-01 and Goldmann tonometer was found (r = 0.173; p = 0.001). Although the mean differences between Goldmann and Tonopen XL, Xpert, and TGDc-01 IOP measurements were statistically significant, the wider 95% LoA was observed when comparing the Goldmann and TGDc-01 tonometers. Computation of the 95% LoA resulted in a wide bias range when comparing the TGDc-01 with all the tonometers used in this study.
  
  
  CONCLUSIONS
  The TGDc-01 "PRA" tonometer was not comparable with the other techniques used in the study. The wide dispersion range of the values obtained shows low repeatability of the TGDc-01 for screening purposes. These results could be because of the technique of measurement and/or interindividual variables.
authors.affiliation: Department of Applied Physics (Optometry Group), University of Santiago de Compostela, 15706 Santiago de Compostela, Galicia, Spain.
authors.forename: Carlos
authors.initials: C
authors.lastname: García Resúa
authors.forename: Maria J
authors.initials: MJ
authors.lastname: Giráldez Fernández
authors.forename: Alejandro
authors.initials: A
authors.lastname: Cerviño Expósito
authors.forename: Javier
authors.initials: J
authors.lastname: González Pérez
authors.forename: Eva
authors.initials: E
authors.lastname: Yebra-Pimentel
mesh_terms: D000328:Adult; D004867:Equipment Design; D005143:Eyelids; D005260:Female; D006801:Humans; D007429:Intraocular Pressure; D008297:Male; D015203:Reproducibility of Results; D014065:Tonometry, Ocular / Q000295:instrumentation* / Q000379:methods* / Q000592:standards