The Joint Assessment Of Material Exposure In Space (James): Laboratory Analyses Of Intraocular Lenses (Iols) After Low-Earth-Orbit Exposure On The Exterior Of The International Space Station (Iss)

To determine whether exposure on the exterior of the International Space Station (ISS) alters intraocular lens (IOL) optical or material properties and to identify differential vulnerability to atomic oxygen (AO), ultraviolet (UV) radiation, and thermal cycling, informing packaging/shielding strategies for low-mass IOL transport and stockpiling for off-Earth cataract care without reliance on climate-controlled crew-cabin storage, as evaluated in the Joint Assessment of Material Exposure in Space (JAMES) project.

International Space Station (ISS) exterior exposure on the Materials International Space Station Experiment (MISSE-20) platform; Berkeley Eye Center (Houston, Texas, USA) & Space Center Houston for IOL-MISSE integration/de-integration; post-flight laboratory analysis at the Intermountain Ocular Research Center, John A. Moran Eye Center, University of Utah (Salt Lake City, USA).

JAMES flew 135 unpackaged intraocular lenses (IOLs) on the Materials International Space Station Experiment (MISSE-20) in three carriers mounted on the International Space Station (ISS) exterior (5 trays/carrier; tray 1 closest to exposure): Ram-facing (high atomic oxygen [AO]), Zenith-facing (high ultraviolet [UV]), and underdeck (partially shielded). Forty-five ground controls were loaded identically on Earth. After ~6 months, 61 flown IOLs were compared with 20 position-matched controls. Lenses underwent gross/light microscopy; abnormal surfaces underwent low-vacuum scanning electron microscopy with energy-dispersive spectroscopy (SEM/EDS); yellowed optics underwent ultraviolet/visible (UV/Vis) transmission spectroscopy (300–850 nm).

Most remained clear (42/61). Dust/salt deposits were common; SEM/EDS showed Na/Cl-rich dried salts on some hydrophilic and collamer lenses, with haze improving after rinse/dry. Findings clustered in tray 1. Ram-facing: 8 lenses (5 hydrophobic acrylic, 2 hydrophilic acrylic, 1 collamer) showed cracks/opacification and surface roughening on SEM; the tray-1 silicone lens did not. Zenith-facing: 4 tray-1 lenses (2 hydrophobic acrylic, 2 silicone) and 1 tray-1 Ram silicone lens yellowed with reduced 400–500 nm transmission. Underdeck: no major changes. All flown light-adjustable lenses (n=6) developed diffuse cobblestone (“bubble-wrap”) microtexture on optic surfaces/edge, even in trays 4–5.

Direct exterior ISS exposure produced direction- and material-specific effects that define IOL failure modes for space logistics. AO-facing exposure was associated with cracking/roughening in acrylic/collamer lenses; UV-facing exposure with yellowing and reduced blue-light transmission in some silicone and hydrophobic acrylic lenses; underdeck placement showed no major changes over 6 months. Light-adjustable lenses demonstrated a unique surface transformation across orientations, suggesting a distinct vulnerability. Findings support targeted shielding/packaging (vs climate-controlled crew cabin storage) to enable low-mass IOL stockpiling for exploration missions and guide higher-resolution materials characterization.