Abstract
Purpose :
In recent years, it has been pointed out that radiation cataracts are at risk from lower doses, and in Japan, the equivalent radiation dose limit was drastically revised to "less than 100 mSv/ 5 years and less than 50 mSv/year" in April 2021 under the Ordinance on Prevention of Ionizing Radiation Damage. We previously studied that unmydriatic lens imaging using a retroillumination lens camera is useful for radiation cataract screening. However, there have been no detailed reports on radiation cataract in medical radiation workers. In this study, we examine the reality of this situation.
Methods :
Among 359 medical workers who used ionizing radiation at the University of Occupational and Environmental Health and the hospital, 336 (mean age 39.0 ± 10.4 years, 211 males and 125 females) who had been individually dosimetrically examined at the same facilities for at least 5 years were included in the study. Lens photographs were taken with retroillumination lens camera in an unmydriatic state, and a photographic determination was made by an ophthalmologist. The subjects were also asked about their history of atopic dermatitis, diabetes mellitus, corticosteroid use, frequency of outdoor activities, and smoking habits, which may affect the lens. Patients with positive findings in the photographs were advised undergo a further examination.
Results :
114 (74 males and 40 females) had cataract findings. The prevalence of findings was 33.9%, broken down by age: 9/58 (15.5%) were in their 20s, 34/136 (25.0%) were in their 30s, 35/84 (41.7%) were in their 40s, 22/40 (55.0%) were in their 50s, and 14/18 (77.8%) were in their 60s. The average annual effective radiation dose for all subjects, including those with findings, was 1.1 ± 3.7 mSv/year. Each subject was within the revised dose limit. None of the workers in their 20s to 40s who had findings of lens opacities had decreased corrected visual acuity below 20/20, but each had several Vacuoles, which are considered early lesions of radiation cataracts, in the lens.
Conclusions :
Lens imaging with a retroillumination lens camera is sensitive to cataract findings and may capture the pathogenesis of radiation cataract in its very early stages. The association of lens micro opacity with radiation dose in young people suggests that radiation cataract may be a stochastic effect rather than a definite effect with a dose threshold as previously thought.
This abstract was presented at the 2024 ARVO Annual Meeting, held in Seattle, WA, May 5-9, 2024.