As human spaceflight pushes toward longer missions to the Moon and Mars, cataract surgery beyond Earth may eventually become a practical necessity. New research presented at the 44th Congress of the European Society of Cataract and Refractive Surgeons (ESCRS) has taken an early step toward understanding whether intraocular lenses (IOLs) can withstand the journey.
Morgan Micheletti, of Berkeley Eye Center in Houston, Texas, led the Joint Assessment Of Material Exposure In Space (JAMES) project, which sent 135 unpackaged IOLs to the International Space Station (ISS). The lenses were positioned outside the ISS in three locations designed to expose them to different combinations of atomic oxygen and solar ultraviolet radiation.
After approximately six months in orbit, the lenses were returned to Earth. Researchers at the Intermountain Ocular Research Center, University of Utah, analyzed 61 space-exposed lenses alongside 20 terrestrial controls. Forty-two of the 61 lenses exposed to space showed no notable exposure-associated findings.
However, changes were observed in the remaining 19. Eight of nine lenses from the most directly exposed location developed cracks and localized surface roughening consistent with early atomic oxygen erosion. Five space-exposed IOLs showed yellow discoloration accompanied by reduced light transmission, particularly between 400 and 500 nm. All six light-adjustable lenses examined also developed a distinctive cobblestone or “bubble-wrap” surface appearance that was absent from corresponding Earth-based controls.
Micheletti stressed that the exploratory study was not designed to compare lens manufacturers or models. Sample sizes were small, the IOLs were deliberately unpackaged, and handling and contamination could not be completely excluded. Further mechanical, optical and clinical-performance testing is also required.
The next stage could involve testing phacoemulsification systems under microgravity conditions, with the longer-term aim of eventually evaluating surgery in orbit.
“The progression has to be deliberate: first the materials, then the equipment, then the procedure and, ultimately, the surgery,” Micheletti said. “My long-term hope is to help make the first eye surgery beyond Earth possible.”
Source: ESCRS Congress.
