PURPOSE: To determine if the atmospheric pressure change experienced during diving can induce changes in the intraocular pressure (IOP) of eyes in a normal population. METHODS: The IOP of 27 healthy volunteers (aged 23,8 +/- 4,9 years old (18-44)) was measured with a Perkins applanation tonometer by two independent investigators, who were blinded to the previous measurements. Measurements were taken at baseline (normal atmospheric pressure of 1 Bar and 24degrees of Celsius), at temperatures of both 28 degrees of Celsius and 24 degrees of Celsius after increasing the atmospheric pressure to 2 Bar in a hyperbaric chamber, at baseline again and finally, at the normal atmospheric pressure of 1 Bar, but a temperature of 28 degrees of Celsius. A multivariate regression analysis was used to evaluate the RESULTS: RESULTS: The mean IOP significantly decreased from 11.8 mmHg in the right eye (RE) and 11.7 mmHg in the left eye (LE) at 1 Bar to 10.7 mmHg (RE) and 10.3 mmHg (LE) at 2 Bar (P = 0.024, RE and P =0.0006, LE). The IOP decrease remained constant during the atmospheric pressure rise period (40 minutes) and was independent of the temperature change. The temperature increase alone did not significantly influence the IOP. CONCLUSIONS: An increase of the atmospheric pressure to 2 Bar (equal to conditions experienced during underwater diving at 10 meters) modestly, but significantly decreased the IOP independent of the temperature change. During the period of increased atmospheric pressure (60 minutes), the IOP decrease remained stable and was independent of blood pressure change or corneal thickness.