title: [Current status of the standardization of air impulse tonometers and their evaluation--as an example: the Non-Contact Tonometer II].
abstract: The standard values and tolerances used in the assessment of the clinical efficiency of different types of tonometers are once again demonstrated. Investigations carried out in accordance with the existing test plan for comparative clinical measurements using two non-contact tonometers II (NCT II) and a calibrated applanation tonometer as a reference instrument in 155 patient eyes showed that both the regression equation and the scattering of the individual values around the regression curve satisfy the conditions of clinical assessment criteria. Of the individual values, 2.6% are outside the 95% limits. Following a brief illustration of the measuring principle of the NCT II, a test procedure is described for this type of tonometer. It consists of a torsion balance mounted on a cross-sliding carriage with a small mirror 2.5 mm in diameter and a control balance. A lens equipped with a centering cross is used for adjustment to the nominal distances of 11 mm between the nozzle and the cornea. This test procedure makes it possible to determine whether the digital display of any particular NTC II deviates from the nominal value by not more than +/- 1 digit in the range between "12" and "30" and by not more than +/- 2 digits between "31" and "50".
mesh_terms: D002138:Calibration / Q000592:standards; D005860:Germany, West; D006801:Humans; D007429:Intraocular Pressure; D014065:Tonometry, Ocular / Q000295:instrumentation / Q000592:standards*
vernacular_title: Gegenwärtiger Stand der Standardisierung von Luftimpulstonometern und ihre Prüfung - Als Beispiel: Das Non-Contact-Tonometer II.