Cataracts in Atomic-bomb Survivors More than 70 Years after Radiation Exposure

Previous ophthalmological studies among atomic-bomb survivors and other radiation-exposed populations have shown a significant association between radiation exposure and cataract, particularly posterior subcapsular cataract (PSC). However, reports of radiation effects on nuclear and cortical cataract are inconsistent. In the current study, we reexamined the issue of radiation effects on cataractogenesis using modern methods and well-defined diagnostic criteria. A questionnaire on ophthalmologic diseases was obtained from 2,439 atomic bomb survivors who were exposed at age 15 or younger and participated in biennial health examinations between November 2015 and March 2020. 684 participants (28%) had already undergone lens extraction in both eyes, and 930 participants and 1,773 eyes were examined by an ophthalmologist at the Radiation Effects Research Foundation. Of these, 876 participants with at least one eye evaluable for cataracts, comprising 1,658 eyes, were the subject of this analysis. Lens images were photographed using a slit lamp, a Scheimpflug camera, and a retro-illumination camera. Nuclear cataract was diagnosed by Scheimpflug images and cortical cataract, PSC, retrodots, waterclefts, vacuoles and those center lens (VCC) was evaluated by retro-illumination images. Odds ratio (OR) at 1 Gy was calculated by generalized estimating equations logistic regression. A significant association between radiation and PSC and VCC was observed (OR: 1.68, 95% confidence intervals (CI): 1.13, 2.50, OR: 1.28, 95% CI: 1.04, 1.57, respectively). No significant associations were observed for nuclear or cortical cataracts (OR: 1.29, 95%CI: 0.93, 1.79, OR: 0.87, 95%CI: 0.67, 1.13, respectively). For other subtypes (retrodots, waterclefts, and vacuoles), there was also no clear evidence of association with radiation. Radiation effects were observed on PSC and VCC, which is the precursor lesion of PSC, even 70 years after exposure. Long-term observation, particularly in other radiation-exposed populations, may be needed to fully appreciate the relationship between radiation and development of cataract.