THE STUDY FOR THE RELATIONSHIP BETWEEN THE DIURNAL VARIATION OF IOP AND SPACEFLIGHT

摘要

Introduction: It has been well known that chronic elevations in intraocular pressure (IOP) are associated with the development of visual impairments, which could lead to a damage of optic nerve fibers with subsequent visual field defects. In fact, the increases in IOP have been observed in microgravity and simulated microgravity. However, there is little information about responses in IOP during spaceflight. Therefore, this study was designed to evaluate the effect of spaceflight on the diurnal variations as well as the magnitude of changes in IOP. Methods: Intraocular pressures with the Pressure phosphene tonometer (PPT) were measured on 1 subject (the first Korean astronaut) during spaceflight. For diurnal variation in microgravity, IOPs measured every 3 hours during day time(x6/day) each day, 2 separate days in ISS: 3 IOP measurements at each time on both eyes. A total 72 measures were obtained under microgravity. To get the control IOP data, IOP measured on same method on ground before space flight. Results: The result showed that mean IOP increased by 26.3% during spaceflight compared to baseline data (13.04±0.74 vs. 16.47 ±0.60 mmHg, p<0.05). IOP measurements during spaceflight increased until Launch+8 days. There was no significant difference in IOP increase during spaceflight between right eye and left eye (16.42±0.65 vs. 16.53 ±0.56 mmHg). There was a different pattern of curve for diurnal variation of IOP during spaceflight compared to the curve of IOP data on ground.Conclusion: The study showed a different pattern of curve for diurnal variation of IOP during spaceflight compared to baseline data on ground. This study has shown that IOP values during spaceflight were increased over ground-based values and that IOP increase lasted until Launch+8 days.