Researchers recently found that astronauts have disc edema-like changes in eye structure after returning to Earth from the International Space Station (ISS).

The study looked at morphological changes in the optic nerve head and surrounding tissues in 15 astronauts after they completed a roughly six-month mission aboard the ISS. The results were compared with 43 healthy control patients with no history of exposure to microgravity in space. After analyzing optical coherence tomography (OCT) data for the astronauts collected before and after the mission, the researchers found three major changes in eye structure.

Before the flight, the astronauts presented with recessed Bruch’s membrane openings compared with the healthy controls. After the mission, their membrane openings were deepened. Additionally, the astronauts showed a noteworthy increase of total retinal thickness near the optic nerve head rim margin, and the total number of eyes with choroidal folds increased.

While determining an exact cause of these changes was not within the study’s scope, the results do point to long-term exposure to microgravity and space travel as a possibility. Beyond that, the researchers believe the algorithms and methods used to determine structural changes could be helpful in both future space travel studies and those here on Earth.

Patel N, Pass A, Mason S, et al. Optical coherence tomography analysis of the optic nerve head and surrounding structures in long-duration international space station astronauts. JAMA Ophthalmol. 2018;136(2):193-200.