Deterioration in the accuracy of the pulsair non-contact tonometer with use: need for regular calibration

Abstract

The Pulsair non-contact tonometer (Keeler Pulsair: Keeler UK) has been shown to be a versatile instrument particularly suitable for screening for raised intraocular pressure. Although demonstrated to be accurate initially when compared to the Goldmann applanation tonometer no study has examined its long-term accuracy. Comparisons of three Pulsair tonometers with different degrees of usage with the Goldmann tonometer are described. Measurements were obtained from 64, 116, and 223 eyes in three separate comparative studies. Correlation coefficients of between 0.78 and 0.90 were obtained, the least used instrument being significantly more accurate than the two more extensively used instruments. Taking the Goldmann tonometer as the standard tonometer, and the aim to detect intraocular pressures of greater than 21 mmHg, sensitivities of 40%, 48%, and 85% for the three Pulsair tonometers respectively were shown. The Pulsair tonometer appears liable to a long-term drift in accuracy with use, and we suggest that provision is made for the regular re-calibration of the instrument.