CLINICAL COMPARISON OF THE KEELER-PULSAIR-2000, AMERICAN OPTICAL MKIIAND GOLDMANN APPLANATION TONOMETERS

The aim of our study was to evaluate the performance of both the Keele r Pulsair 2000 and the American Optical (AO) MkII non-contact tonomete rs (NCT) and compare these to the reference Goldmann standard using th e same group of patients. Forty-five patients (89 eyes) receiving medi cal treatment for primary open angle glaucoma had their intraocular pr essure (IOP) measured with each instrument in a random order using fiv e experienced observers. In the IOP range of the sample (6-27 mmHg) th e difference between means for each tonometer was small. The Pulsair 2 000 (mean = 19.06 mmHg, SD 6.28) read slightly higher than Goldmann (m ean = 18.01 mmHg, SD 4.88), whereas the AO MkII read slightly lower (m ean = 16.27 mmHg, SD 5.93). However, all differences were statisticall y significant (P < 0.001, repeat measures ANOVA), Correlation coeffici ents for Pulsair 2000 versus Goldmann was r = 0.82 and for AO MkII ver sus Goldmann was r = 0.85. In addition, the repeatability for each NCT was assessed using 10 consecutive measurements on a further 10 subjec ts. The Pulsair 2000 showed significantly greater variation of IOP (me an SD 3.43 mmHg) than the AO MkII (mean SD 1.76 mmHg), confirming the need for taking at least four readings per eye with the Pulsair 2000. These variations are greater than that generally observed with Goldman n, and possible explanations why this occurs are discussed. In conclus ion, subject to these limitations, both NCTs should be useful for meas uring IOP as part of a screening protocol for glaucoma.