Six months outside the ISS left most intraocular lenses intact, but every light-adjustable lens came back altered
In the JAMES experiment, 135 intraocular lenses spent about six months mounted on the outside of the International Space Station without packaging. Of the 61 examined so far, 42 showed no change linked to exposure; eight of nine acrylic lenses in the carrier facing the direction of flight cracked, five lenses yellowed, and the six light-adjustable lenses all came back with a cobblestone texture whose origin is still unknown. Morgan Micheletti presented the results at the ESCRS congress in London as an exploratory step towards eye surgery in space.
Science··Morning
135 lenses rode outside the station for six months
Morgan Micheletti, a Houston cataract surgeon at the Berkeley Eye Center, unveiled the first results of JAMES, the Joint Assessment Of Material Exposure In Space, on Sunday in London at ESCRS, the 44th congress of Europe's cataract and refractive surgeons' society. The project sent 135 intraocular lenses, the implants used in cataract surgery, to the International Space Station without their packaging and mounted them in carriers named CLAIRE at three points on the station's exterior: Ram, facing the direction of flight and bathed in atomic oxygen; Zenith, turned towards the Sun's ultraviolet light; and Underdeck, tucked beneath the exposure platform and partly shielded from both. Another 45 lenses, unpacked in the same way, stayed on Earth at room temperature and normal pressure as controls. After roughly six months in orbit the flight lenses came home, and Liliana Werner's team at the Intermountain Ocular Research Center of the University of Utah went over 61 of them and 20 of the controls, checking clarity, whether the material had held together and what had settled on the surfaces. Micheletti told the congress the aim was not to mimic how a packed lens would travel to Mars but to expose failure modes under harsh conditions, so that packaging, shielding, storage and material choices can be settled before anyone needs them.[1]
Acrylics cracked facing the flight direction; every light-adjustable lens came back cobblestoned
Forty-two of the 61 examined flight lenses showed nothing that could be tied to their time outside. The other 19 fell into three patterns. In the Ram carrier, eight of nine lenses showed cracks and patches of surface roughening consistent with early erosion by atomic oxygen; all eight were acrylic, five hydrophobic and three hydrophilic, while the ninth, a silicone lens, had yellowed. Five flight lenses in all had turned yellow, two hydrophobic acrylic and three silicone, four of them from the Zenith carrier and one from Ram, and spectrophotometry measured reduced light transmission through them, most markedly between 400 and 500 nanometres. The third pattern is the one still without an answer: all six light-adjustable lenses that flew, spread across the three positions, came back with a cobblestone or bubble-wrap texture on both surfaces and along the edge of the optic, while neither of the two matching lenses kept on Earth showed it. The mechanism is unknown, and the researchers say an explanation unrelated to direct space exposure cannot yet be ruled out.[1]
An exploratory first step, with surgical equipment next in line
Micheletti described the work as exploratory and descriptive rather than a comparison of lens makes or a test of a hypothesis: the analysis covered a selected part of the payload, lens counts were small and uneven, some carrier positions held a single lens of a given model, the unpackaged lenses could have picked up handling or environmental contamination, and the Earth controls never went through launch, return or flight handling, which limits how firmly the changes can be pinned on exposure. Image-quality, mechanical and clinical-performance testing is still to come, and the findings say nothing about the safety of routine cataract surgery on Earth or about how a lens already implanted in an eye behaves in space. The team plans next to test a phacoemulsification system, the ultrasound and fluid device that breaks up and removes the cloudy natural lens, during the short spells of weightlessness on parabolic flights, with an in-orbit surgical experiment as the eventual goal. Joaquín Fernández, the ESCRS secretary, who was not involved, called it forward-thinking preparation for deep-space exploration.[1]
