Intraocular pressure response affected by changing of sitting and supine positions.

PURPOSE: To assess the intraocular pressure (IOP) time response to change in body position from sitting to supine and from supine to sitting immediately and during rest in each position. METHODS: Forty-four visually healthy volunteers were recruited for the study. The experiment consisted of the initial sitting position (baseline state), the subsequent lying period and the final sitting period. Both periods were 30 min long. The IOP was measured in the baseline state, immediately after each position change and then in minutes 5, 15, 25 and 30 during each period. The Icare Pro® rebound tonometer was used. RESULTS: The mean IOP increased after each position change (2.6 ± 2.4 mmHg after lying down and 2.1 ± 3.1 mmHg after sitting up) and then gradually decreased with time. The mean IOP was 1.41 ± 2.4 mmHg higher in the lying period than in the sitting period; the mean difference was smaller for the lower baseline (0.9 ± 2.2 mmHg) than the higher baseline (1.9 ± 2.5 mmHg). The mean IOP in the final sitting was significantly lower (2.5 ± 1.9 mmHg) than in the initial sitting position. The effect of sex was insignificant. CONCLUSIONS: There was an immediate increase in IOP as a response to both changes in the body position and the subsequent gradual decrease with time. The IOP difference between lying and sitting position was depended on baseline.

Intraocular Pressure Response to Maximal Exercise Test during Recovery.

SIGNIFICANCE: The main aim of this study was to determine the intraocular pressure (IOP) response to maximal incremental running test during 30 minutes of recovery. Exhaustive exercise induced a highly individually variable IOP response, which was related to its initial value and the initial heart rate. PURPOSE: The purpose of the study was to analyzed the IOP response to a maximal incremental running test in healthy women during a 30-minute recovery period. Secondarily, the study attempted to determine if the IOP was dependent on its baseline, maximal oxygen uptake, initial heart rate, and autonomic nervous system regulation. METHODS: Twenty-four healthy women between the ages of 19 and 30 years were recruited for the study. Initial IOP (baseline), heart rate, and autonomic nervous system regulation were measured after 30 minutes of rest. Each subject then underwent an incremental running test on a treadmill to reach the maximal physical activity and to determine physical fitness based on maximal oxygen uptake. Intraocular pressure and autonomic nervous system activity were measured immediately after completion of the physical activity during a 30-minute recovery period in the supine position. RESULTS: The IOP variability increased markedly after the exercise up to 1.7-fold of the resting state. The IOP before and after exercise did not differ significantly; however, the lower baseline revealed a significant increase in comparison with the higher baseline. The time course of the IOP changes was significantly influenced by the initial heart rate. All other effects, interactions, and correlations were insignificant. CONCLUSIONS: The IOP response after maximal exercise was highly dependent on the individual. The IOP seems to be slightly increasing with a significant dependence on its resting baseline and initial heart rate.

Intraocular Pressure Response to Short-Term Extreme Normobaric Hypoxia Exposure.

Purpose: The purpose of the study was to determine the intraocular pressure response to normobaric hypoxia and the consequent recovery under additional well-controlled ambient conditions. Second, the study attempted to determine if the intraocular pressure changes were dependent on its baseline, initial heart rate, sex and arterial oxygen saturation. Methods: Thirty-eight visually healthy volunteers (23 women and 15 men) of an average age 25.2 ± 3.8 years from 49 recruited participants met the inclusion criteria and performed the complete test. Initial intraocular pressure (baseline), heart rate, and arterial oxygen saturation were measured after 7 min of rest under normal ambient conditions at an altitude 250 m above sea level. Each subject then underwent a 10 min normobaric hypoxic exposure and a subsequent 7 min recovery under normoxic conditions. Within hypoxic period, subjects were challenged to breathe hypoxic gas mixture with fraction of inspired oxygen of 9.6% (~6.200 m above sea level). Intraocular pressure and arterial oxygen saturation were re-measured at 4 and 10 min during the hypoxia and at 7 min after hypoxia termination. Results: Intraocular pressure increased in 1.2 mmHg ± 1.9 mmHg and 0.9 mmHg ± 2.3 mmHg at 4 and 10 min during the hypoxic period and returned approximately to the baseline at 7 min of recovery. The influence of sex was not statistically significant. The arterial oxygen saturation decreased in 14.9 ± 4.2% at min 4 and 18.4 ± 5.8% at min 10 during hypoxia and returned to the resting value at 7 min of recovery. The decrease was slightly higher in the case of women if compared with men. The hypoxia induced changes in intraocular pressure were significantly correlated with the arterial oxygen saturation changes, whereas the relationship with intraocular pressure baseline and initial heart rate were insignificant. Conclusion: There was a significant increase in intraocular pressure as a response to short-term normobaric hypoxia, which returned to the baseline in 7 min after hypoxia. The increase was dependent on the induced oxygen desaturation.

Intraocular Pressure Response to Moderate Exercise during 30-Min Recovery.

PURPOSE: The aim of the study was to evaluate intraocular pressure (IOP) before and after moderate exercise in normal healthy individuals with defined physical exertion. The second aim of this investigation was to determine the correlation between resting IOP (IOPr) and its change induced by exercise as well as the relationship between resting heart rate (HRr) and changes in IOP after exercise. METHODS: Forty-one healthy volunteers between the ages of 19 and 25 years were recruited for the study. First, the resting (reference) values IOPr and HRr were measured after 30 min of resting time. Volunteers consequently performed 30 min of exercise on a bicycle ergometer. Intraocular pressure was remeasured immediately after the end of exercise (the relevant IOP change was denoted as ΔIOP0) and subsequently repeated 5, 10, 20, and 30 min after exercise. RESULTS: A significant decrease in IOP compared with the resting value (post hoc Tukey honest significant difference test) was found immediately after exercise (p = 2 × 10) and 5 and 10 min after exercise (p = 2 × 10 and p = 3 × 10). Significant relationships were found between the change in IOP (ΔIOP0) and baseline IOP (IOPr) and between the baseline resting heart rate (HRr) and the change in IOP (ΔIOP0). CONCLUSIONS: There was a significant IOP-lowering effect, which was persistent for 10 min after 30 min of exercise. The IOP change was dependent on the initial IOP reading and initial HR.