SONOGRAPHIC EVALUATION OF SPACE FLIGHT EFFECTS ON THE EYE AND ORBIT

INTRODUCTION: The structural information obtained by eye and orbit sonography in astronauts exposed to microgravity is important and must be characterized using quantitative and qualitative techniques. METHODS: Multipurpose ultrasound imagers with high-frequency linear-array probes were used in preflight, in-flight and post-flight phases of short- duration and long-duration space flight missions to conduct a standardized protocol of the globe and optic nerve imaging. Subsequent analysis included quantification of the optic nerve and its sheath, as well as semi-quantitative assessment of the shape and structure of the posterior pole of the globe, optic nerve, and optic nerve sheath. RESULTS: The results of the ultrasound analysis demonstrated changes in eye and orbit anatomy that were consistent with elevated intracranial pressure in a subset of the subjects. These changes varied in severity and combination of particular signs. Globe flattening observed in this group appeared to differ among those affected in its intensity as well as in its nature; some subjects displayed choroidal engorgement while other patients demonstrated full-thickness globe flattening as the dominant mechanism for a flattened retinal surface. Mild flattening may not have reached the macular area therefore not affecting visual acuity. DISCUSSION: A number of sonography-derived quantitative and qualitative parameters clearly coexist in the same individuals. These exams may also be useful in determining the dominant mechanisms of vision change in affected individuals.