Experimental Radiation Cataract

IN PREVIOUS reports of this series 1 describing the ocular events in rabbit eyes following exposure to x-rays and neutrons, abnormalities in the lenses were unexpectedly found at the lowest dose levels used (250 r for x-rays and 1.0 X 10 9 neutrons/cm. 2 ). It is the purpose of this communication to report the effects on the lenses of rabbits of a single exposure to x-rays and to neutrons at lower dose levels and to present a calculation of the energy released in the lens with exposure to comparable cataractogenic doses of x-rays and of neutrons. At the outset the difficulties inherent in determining a threshold level may be mentioned. Thus, if no opacification of the lens occurs with a given amount of radiation, the objection may legitimately be raised that the observations have not been followed over a sufficiently long period; it is well known that the lower the