Language selection


Top of page

SANSORI: Does rigid eye structure help protect astronauts' eyesight?

Health science

The SANSORI experiment will investigate the factors involved in vision changes experienced by some astronauts during six-month missions.

European Space Agency astronaut Matthias Maurer explains how a Canadian experiment is investigating vision changes experienced by astronauts during six-month missions aboard the International Space Station. (Credit: Canadian Space Agency, NASA, European Space Agency, Rosemont-Maisonneuve Hospital)


Human vision is naturally adapted to the conditions of life on Earth. But when astronauts spend several months in space, both their eyes and eyesight can change and result in blurry or altered vision.

This condition is called Spaceflight-Associated Neuro-Ocular Syndrome (SANS), and it affects 45 to 75 percent of astronauts during six-month space flights. It could be caused by the extra pressure that builds in astronauts' heads when their body fluids shift in a weightless environment.

Scientists are investigating why SANS is so common. For this experiment, Canadian researchers will study whether astronauts who have a particularly rigid eye structure – caused by stiffness in the outer coating of the eye – are less likely to develop SANS. They will also examine whether SANS is more likely to happen when blood vessels in the choroid (a thin layer of tissue in the eye) become engorged.

ESA astronaut Alexander Gerst takes optical measurements to help characterize the risk of SANS to crew members assigned to six-month flights on board the International Space Station. (Credit: NASA)


SANSORI aims to:

 Impacts on Earth

Although SANS is a condition that applies specifically to vision changes in astronauts, the knowledge we gain from the SANSORI experiment could help researchers better understand vision problems on Earth.

SANSORI will contribute to what we know about conditions such as glaucoma, idiopathic intracranial hypertension (high blood pressure in the head without known cause) and certain cardiovascular diseases – conditions that, like SANS, are at least partly caused by increased pressure in the head. This research can also help us understand the effects of pressure changes in patients' heads and eyes when they are on prolonged bedrest.

How it works

The SANSORI experiment will test 13 astronauts:

  1. Researchers will collect data about astronauts' eyesight and the physical properties of their eyes before, during and after their space flights. Researchers will use:
    • questionnaires about the astronauts' visual acuity
    • various scans, videos and imaging of the eyes to measure astronauts' eye pressure
    • ophthalmic MRI reports
    • information from exercise sessions
  2. Researchers will use data sharing to access as much information about the astronauts' vision as possible, and to ensure they have a complete picture of the astronauts' medical history.


Data collection for SANSORI began in . The study is scheduled to conclude in late .

JAXA astronaut Koichi Wakata collects optical data on the International Space Station. (Credit: NASA)

Research team

Principal investigator

  • Dr. Santiago Costantino, Université de Montréal


  • Dr. Mark Lesk, Université de Montréal, Hôpital Maisonneuve-Rosemont

Explore further

Date modified: