Astronauts Face Vision Crisis After Prolonged Space Missions, NASA Intensifies Solutions

NASA has raised concerns after multiple astronauts returning from extended space missions reported significant and potentially irreversible changes in their vision. According to recent findings, nearly 70% of astronauts who spend months in microgravity environments develop a condition now termed Spaceflight-Associated Neuro-Ocular Syndrome (SANS).

The syndrome, first identified more than a decade ago, includes symptoms such as flattened eyeballs, swelling of the optic nerve, folds in the retina, and vision impairment. These symptoms often worsen during prolonged exposure to microgravity. Scientists have found that the fluid shifts in the absence of gravity lead to increased pressure inside the skull, which directly affects the eyes.

SANS causes optic disc swelling at the point where the optic nerve enters the retina, along with subtle eyeball flattening. Astronauts, including NASA’s Dr. Sarah Johnson, have reported blurred vision and difficulty reading during six-month ISS stays. In a notable case, astronaut John Phillips’ vision worsened from 20/20 to 20/100 after a six-month mission in 2005. These alterations may persist for years after returning to Earth.

NASA researchers observed these symptoms in astronauts aboard the International Space Station (ISS), particularly those who stayed for more than six months. In some cases, the changes did not fully reverse even after returning to Earth. This raises concerns about the health risks of upcoming missions, especially the planned human mission to Mars, which would require astronauts to spend at least three years in microgravity.

Dr. Michael Roberts, NASA’s vision research lead, emphasized the urgency of developing countermeasures. “We need to understand whether these changes stabilise or continue worsening over time. An astronaut with severely compromised vision could jeopardise an entire Mars mission.” he said.

NASA’s 2015–2020 Fluid Shifts study confirmed that altered blood drainage from the brain in weightlessness contributes to SANS. The Vision Impairment and Intracranial Pressure (VIIP) project linked these fluid shifts to increased brain pressure, using MRI scans, retinal imaging, and eye exams. Canadian researchers using Optical Coherence Tomography found mechanical similarities to glaucoma in affected eye tissues, while Japan’s space agency reported gene expression changes in the optic nerves of space-flown mice.

To combat this, NASA is testing several interventions. These include special contact lenses that redistribute fluid, medications to control intracranial pressure, and exercise regimens that promote healthy fluid circulation. Devices that simulate gravity or apply negative pressure to the lower body are also being evaluated.

Roberts and his team are actively exploring pharmacological options, nutritional supplements such as B vitamins, and environmental modifications like reducing cabin carbon dioxide levels. One astronaut showed improvement after such measures. NASA is also testing VIIP chambers to mimic Earth-like eye pressure and lower-body negative pressure suits to recreate gravity’s downward pull on fluids.

The issue came into renewed focus after the recent return of astronauts Sunita Williams and Butch Wilmore from the Boeing Starliner mission. Experts say they may experience not just visual disturbances, but also puffy faces, altered skin texture, and a temporary loss of balance due to gravity readjustment. NASA continues to monitor their recovery closely.

As missions to the Moon and Mars approach, the potential impact of “space blindness” has become one of the most urgent biomedical challenges. The long-term impact of space travel on human health remains a key challenge for interplanetary exploration. In the process, SANS research may also shed light on Earth-bound conditions like glaucoma and intracranial hypertension, offering broader medical benefits.

(Rh/Eth/MSM/SE)