Clinical performance of the Reichert AT550:: a new non-contact tonometer

The aim of the present study was to assess the level of accuracy for measurements of intra-ccular pressure (IOP) obtained with a new non-contact tonometer (NCT) the Reichert AT550(R). Measurements were compared against those obtained with the Reichert Xpert Plus, Goldmann applanation tonometer and Perkins tonometer. Thirty-five university students were assessed with the four tonometers in a randomised order, with non-contact tonometry performed first. Each of the four measurement devices had its own trained clinical observer. Plots of differences of IOP as a function of the mean for each pair of instruments were obtained. No statistically significant differences were found when comparing the AT550(R) NCT with contact applanation tonometry (AT) (p > 0.05), displaying the closest level of agreement (as represented by the lowest mean difference and the narrowest confidence interval) with the Goldmann tonometer (limits of agreement, 0.12 +/- 2.17). In conclusion, readings of IOP with the AT550(R) NCT are clinically comparable with those obtained with Goldmann tonometry in a population with IOP within the normal range.