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Published in:
2021 | OriginalPaper | Chapter
21. Late Effects of Space Radiation: Cataracts
Authors : E. A. Blakely, P. Y. Chang
Published in: Handbook of Bioastronautics
Publisher: Springer International Publishing
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Abstract
Purpose
Cataracts can arise from several different etiologies due to inherent genetics, or to physiological abnormalities in an organism, or due to exposure to toxic insults. Exposure of the lens to doses of ionizing radiation (IR) greater than 2 Gy is well recognized as a risk factor for cataract.
Methods
This review of recent literature provides evidence for different manifestations of cataract in terms of radiation dose parameters (e.g., dose level, the ionization density of the radiation), the morphological appearance of the opacifications, and the time of presentation after exposure in human cohorts and different animal species. Molecular and cellular studies contributing to our understanding of the underlying mechanisms of action of IR-induced cataract are also discussed.
Results
Data show that IR-induced cataract is a progressive lesion, with several different morphological manifestations in the body of the lens during maturation of the opacification, involving multiple molecular and cellular pathways, as well as potentially direct effects on crystalline proteins. Prior work had indicated a dose threshold at 2 Gy, but with improvements in detection technologies, it is now clear that the threshold, if it exists, is 0.8 Gy or less.
Conclusions
Significant molecular and cellular changes occur in the lens during the latency period between lens exposure to IR and the appearance of a cataract. In April 2011 the International Commission on Radiation Protection, an advisory body providing recommendations and guidance on radiation protection reduced the recommended dose limit to the lens, not to exceed 0.5 Gy in a single exposure.