Space travel can wreak havoc on the ocular system for reasons partially understood, but insights we glean from how the eye acts in microgravity can inform how we diagnose and treat diseases back on Earth.
Astronauts can experience changes to their eyes and vision during spaceflight, a phenomenon coined Spaceflight Associated Neuro-Ocular Syndrome (SANS). Microgravity causes a person’s blood and cerebrospinal fluid to shift toward the head and, as a result, visual and anatomical changes have been reported such as optic disc edema, globe flattening, choroidal folds and hyperopic shifts.
Our research is focused on the anterior segment of the eye – the first to investigate dry eye disease (DED) and the tear film in space-like conditions. We achieve this by undertaking parabolic flights that create short periods of microgravity through precise flight patterns, as a precursor to orbit-based research.
DED is a significant ocular issue thought to affect about 15% of the population, with a higher prevalence in women and older people. But it’s also related to daily activities such as eye strain from computer use and sleep behaviour. Astronauts are particularly afflicted, with about 30% experiencing symptoms during long-term space missions.
The zero-gravity environment and the dry, enclosed cabin atmosphere are likely the biggest contributors to DED developing in space. Several other factors are likely involved, including tear film instability and ocular surface inflammation. Additionally, the space environment exposes the eyes to floating dust, artificial lighting, and prolonged screen use, which present further risk of ocular surface damage. Fluid shifts within zero gravity cause eyelid swelling and disrupted tear drainage, likely leading to tear retention and the buildup of irritants.
Our group is being led by Dr Timon Ax, MD, a PhD student at Western Sydney University. Professor Jennifer Craig, a prominent research optometrist in the Department of Ophthalmology at the University of Auckland, is also part of the team.
We believe understanding DED in space will help protect astronauts’ eye health but, importantly, offer insights into the mechanisms of DED on Earth.
Next, the question becomes: could this lead to innovative diagnostic and therapeutic solutions for DED? We think so. A microgravity environment isn’t conducive to many current therapies: imagine trying to use an eye drop in space? But in all seriousness, there’s potential for portable, miniaturised and non-invasive technology to be used by astronauts before being repurposed for Earthlings.
The possibilities include diagnostic technologies such as infrared imaging to assess the tear film in real-time, or therapeutic devices such as ocular neurostimulators that stimulate tear production and alleviate DED symptoms at the push of a button.
These advancements have significant implications for improving eyecare on Earth, particularly in remote or resource-limited settings such as rural areas, as well as in space.
The study team comprises medical doctors, researchers, and engineers in collaboration with the German Aerospace Center (DLR) and Novespace in France.
We’re operating at the nexus of space medicine, ophthalmology and engineering. This interdisciplinary collaboration is essential for advancing our understanding of DED in space and developing effective interventions.
We have future research planned that will focus on other eye conditions to contribute to the overall improvement of ocular health in space and on Earth.
ABOUT THE AUTHOR:
Name: Dr Francesc March de Ribot
Qualifications: MD, PhD
Affiliations: University of Otago, Eye department, Department of Medicine
Location: Dunedin, New Zealand
Years in industry: 17
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