VISION IMPAIRMENT AND INTRACRANIAL PRESSURE (VIIP)
Research Area: Human Research: Integrated Physiology and Nutrition
Expedition(s): 1-ongoing
RESEARCH OBJECTIVES
Vision Impairment and Intracranial Pressure (VIIP) project examined the effect of long-term
exposure to microgravity on the structure of the eye along with change in distance and near
vision of crew members before and after they returned to Earth.
EARTH BENEFITS
New knowledge is expected to be
the major benefit of this project.SPACE BENEFITS
Possible countermeasures may be
developed to mitigate space-
induced ocular impairments.RESULTS
Since 1989, as part of the
postflight eye examination,
astronauts were queried as to
whether they perceived a
subjective improvement or
degradation in distant or near
vision (none, mild, moderate, or
severe) during their short- and long-duration missions. Prompted by persistent reports of vision
changes, NASA began a stepwise operational process to determine the c ause(s). Several
ophthalmic procedures were initiated on astronauts, including dilated fundus (the rear portion
of the eye) examinations with binocular ophthalmoscopy, cycloplegic refraction, optical
coherence tomography (OCT), magnetic resonance imaging (MRI) of orbits, and fundus
photography for before and after space missions.
In a follow-up study, twenty-seven astronauts underwent thin-section, three-dimensional, eye
orbital, and conventional MRI brain scans. Eight astronauts underwent repeat imaging after an
additional mission in space. All astronauts had previous exposure to microgravity. Image
analysis of the optic nerve sheath, optic disc, posterior globe, and pituitary gland was
performed and compared for association with intracranial evidence of excessive fluid buildup
inside the skull, cells, tissues, or body cavities, venous blood clotting in the brain and/or mass
lesion.
Visual acuity degradation in astronauts exposed to microgravity is a newly recognized
phenomenon. Although the exact mechanism is yet to be fully determined, many MRI findings
suggest that intracranial hypertension is an important component. However, a large proportion
ISS030E235670 – Don Pettit performs Ultrasound Eye Imaging in
the Columbus Module of International Space Station during
Expedition 30. Image courtesy of NASA.