Are Medications Involved in Vision and intracranial Pressure Changes Seen in Spaceflight?

Some crewmembers have experienced changes in their vision after long-duration spaceflight on the ISS. These impairments include visual performance decrements, development of cotton-wool spots or choroidal folds, optic-disc edema, optic nerve sheath distention, and/or posterior globe flattening with varying degrees of severity and permanence. These changes are now used to define the visual impairment/intracranial pressure (VIIP) syndrome. The reasons for these potentially debilitating medical issues are currently unknown. The potential role of administered medications has not yet been examined, but it is known that many medications can have side effects that are similar to VIIP symptoms. Some medications raise blood pressure, which can affect intracranial pressure. Many medications that act in the central nervous system can affect intracranial pressures and/or vision. About 40% of the medications in the ISS kit are known to cause side effects involving changes in blood pressure, intracranial pressure and/or vision. For this reason, we proposed an investigation of the potential relationship between ISS medications and their risk of causing or exacerbating VIIP-like symptoms. The purpose of this study was to use medication usage records for affected and unaffected crew to determine if use of particular medications seemed to correlate with VIIP occurrence or severity