Airpuff tonometry versus applanation tonometry.

In order to study the reliability of airpuff tonometry, 230 eyes of 115 patients had their IOP measured with 2 airpuff tonometers, NCT and Pulsair, and one applanation tonometer, Perkins handheld Goldmann Type, between Dec 87 and March 89. Each patient had three readings per eye with each airpuff instrument and two readings per eye with the Perkins instrument. Mean age for the group was 68 +/- 11 (SD), range 36-87 years. The mean values were for Perkins: 21.21 +/- 6.27 R.E., 21.28 +/- 5.67 L.E.; for NCT: 21.11 +/- 6.95 R.E., 21.27 +/- 5.41 L.E.; for Pulsair: 23.05 +/- 6.00 R.E., 23.76 +/- 5.39 L.E. The ranges were for Perkins: 9-45 R.E., 9-38 L.E.; for NCT: 8-59 R.E., 11-38 L.E.; for Pulsair: 9-52 R.E., 11-38 L.E. For the Pulsair a value of 18 was found to be a cut-off point below which there were no false negatives, and for the NCT this value was found to be 17. A linear relation between airpuff and applanation tonometry was found, but also a large spread, both for false positives and false negatives.