Measurement of Intraocular Pressure with a Modern Noncontact Tonometer

Abstract

Purpose: To evaluate the intraocular pressure (IOP) in a population without known glaucoma as measured by means of a noncontact tonometer (NCT). Methods: IOP values of 842 persons, measured by means of a Pulsair 2000 NCT ® (Keeler Instruments, Inc., Broomhall, Pennsylvania) by 5 investigators were evaluated. Three consecutive measurements were taken first on the right eye and then on the left eye in each subject. Topical anesthesia was not used. Results: The distribution of the measured IOP values was significantly different from a normal distribution. The median IOP was 15.0 mm Hg (lower quartile/upper quartile 12.5/17.2). There were no differences in IOP values between male and female subjects or between right and left eyes. There was no correlation between age and IOP values. Ninety percent of the subjects had an IOP within a range of 9–24 mm Hg in both eyes. Among the examined subjects, the IOP was above 24 and 21 mm Hg in 4,6 and 11%, respectively, in at least one eye. The median range of consecutive IOP measurements in one eye was 3 mm Hg (lower quartile/upper quartile 2.0/4.0). The median interocular IOP difference was 1.7 mm Hg (0.7/2.7). The median individual coefficient of variation (CV) values were 10.0% for the right eyes, –10.8% for the left eyes. Among the 5 different examiners, the IOP values, range of 3 consecutive IOP readings in one eye, interocular asymmetry and CV values were statistically comparable. Conclusion: The Pulsair 2000 NCT is very simple to use and its handling is mostly independent of the operator. The results of the present investigation might be of some value for future screening programs.