[Variation of intraocular pressure by non-contact tonometry and cardiac pulse wave].

We performed successive IOP measurements with a noncontact tonometer (NCT) in twelve eyes of six normal volunteers to analyze the relationship between the variation of IOP and the cardiac cycle. For this study, we devised a special apparatus composed of an photoelectric plethysmograph, an electric cardiograph and a NCT. With this apparatus, non-contact tonometry was permitted only at the peak or trough of the cardiac pulse wave. At the peak or trough of the cardiac pulse wave, IOP showed a variation of 0.8 +/- 0.4 mmHg (mean +/- s.d.) which was thought to be caused mainly by respiration. Between the peak and trough of the cardiac pulse wave, we found a maximum difference in IOP of 3.8 +/- 1.0 mmHg and a mean difference of 1.9 +/- 0.8 mmHg, which seemed to be attributable to the cardiac cycle.