BACKGROUND: The aim of the present study was to examine the influence of phasic stressors on intraocular pressure (IOP). SUBJECTS AND METHODS: We exposed 15 ophthalmologically and systemically healthy non-smoking subjects (m:f = 8:7; mean age 25.4 years) to both bicycle ergometry physical stress and a computer-game psychological stress. IOP, blood pressure, and subjective stress were measured. To adjust for between-subject variance, we calculated intra-subject z-scores based on IOP values. Because of the habituation occurring during repeated tonometric measurements, we tested the significance of the difference between the observed and expected IOP z-values for each of the stressors. The expected IOP value was the mean of the pre- and post-stress relaxation-period values. Student's t-tests were used to assess the impact of the stressors on blood pressure. RESULTS: Both stressors increased the systolic blood pressure, but only under mental stress was the intraocular-pressure increase statistically significant (p = 0.048). DISCUSSION: The selective increase in intraocular pressure during mental stress by similar reaction of blood pressure to both stressors is a hint for possible different regulation circuits in the autonomic nerve system for intraocular- and blood pressure, respectively. Additionally, it was possible to demonstrate that mental stress could lead to a rise in intraocular pressure.