Cataract development after internal radium-224 exposure
A. K. Junk, F. H. Stefani, H. Spiess, H. Roos, A. M. Kellerer
Background: From 1944 to 1951, a German physician revived Radium-224-injections as a therapy for bone tuberculosis and Ankylosing Spondylitis. Hypothesizing that adding traces of Platinum and Eosin, a red dye, would direct the isotope to inflamed areas in the bone and cause a selective irradiation, he was granted generous support from an insurance company. Although experimental studies soon showed that Radium-224 had no tuberculostatic effect but in fact concentrated in the epiphyseal plates resulting in retarded growth and bone cancer, over 2000 patients were exposed by 1952. Since the first cataract was reported in 1956 cataract prevalence increased continuously. As the patient population aged differentiating radiation and senile cataract became important.
Patients and Methods: A mobile digital Scheimpflug imaging system was employed to document and objectively evaluate lens findings. Between 1993 and 1997 25 individuals exposed as children and juveniles (age at exposure below 20), and 4 adults (exposure at age 20 or above) were examined. Digital Scheimpflug image analyses of 5 anatomically defined lens regions generated calibration units as a measure of lens opacity. These data were compared to the database of a control cohort.
Results: Images illustrating the different clinical presentations of cataract in these patients are provided. Variations in location, cataract density and senile changes are depicted. Compared to the control group, calibration units were within normal limits in the anterior capsule, anterior cortex and the nucleus. However, in the posterior cortex and posterior subcapsular areas calibration units were elevated, indicating unusual lens opacity.
Conclusion: Our patient series demonstrates lens changes consistent with radiogenic cataracts. Radiation cataracts classically appear in the posterior subcapsular region following a latent period, the length of which is inversely related to dose. The initial posterior subcapsular cataract may either progress to a denser opacity or is displaced into the posterior cortex by subsequent fibrogenesis. Lens growth may be slower than normal, resulting in a reduced antero-posterior lens thickness for the patients' age.
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