Morphological and cell volume changes in the rat lens during the formation of radiation cataracts

Evaluation of cataract formation in fish exposed to environmental radiation at Chernobyl and Fukushima

Recent studies apparently finding deleterious effects of radiation exposure on cataract formation in birds and voles living near Chernobyl represent a major challenge to current radiation protection regulations. This study conducted an integrated assessment of radiation exposure on cataractogenesis using the most advanced technologies available to assess the cataract status of lenses extracted from fish caught at both Chernobyl in Ukraine and Fukushima in Japan. It was hypothesised that these novel data would reveal positive correlations between radiation dose and early indicators of cataract formation. The structure, function and optical properties of lenses were analysed from atomic to millimetre length scales. We measured the short-range order of the lens crystallin proteins using Small Angle X-Ray Scattering (SAXS) at both the SPring-8 and DIAMOND synchrotrons, the profile of the graded refractive index generated by these proteins, the epithelial cell density and organisation and finally the focal length of each lens. The results showed no evidence of a difference between the focal length, the epithelial cell densities, the refractive indices, the interference functions and the short-range order of crystallin proteins (X-ray diffraction patterns) in lens from fish exposed to different radiation doses. It could be argued that animals in the natural environment which developed cataract would be more likely, for example, to suffer predation leading to survivor bias. But the cross-length scale study presented here, by evaluating small scale molecular and cellular changes in the lens (pre-cataract formation) significantly mitigates against this issue.

Mass alteration in the lens after exposure to radiation in the 300 nm wavelength region

The purpose of the present investigation was to elucidate whether radiation in the 300 nm wavelength region (300 nm UVR) induces an alteration of lens mass. Lenses from 12 rabbits were incubated in vitro and the relative wet mass gain was recorded sequentially. The wet mas gain, at 30-40 h postictal interval, was greater in lenses exposed to 3.0-6.0 kJ/m2 300 nm UVR than in non-exposed contralaterals. The coefficients of variation were between 6-10% in determinations of wet mass, dry mass, and mass of lens water in Sprague Dawley rat lenses, the variation among animals being the largest source of inprecision. One eye in each of 80 rats was exposed in vivo to 30 kJ/m2 300 nm UVR, and the rats were sacrificed in groups at consecutive postictal intervals. The in vivo exposure of a lens to 300 nm UVR induced a water accumulation after around 24 h and a reduced increase of dry mass, as compared to in the contralateral non-exposed lens.