The Incidence Risk for Primary Glaucoma and Its Subtypes following Chronic Exposure to Ionizing Radiation in the Russian Cohort of Mayak Nuclear Workers

Purpose: To assess the incidence risk of primary glaucoma in a cohort of workers affected by chronic exposure. Material and methods: The studied cohort included all workers first employed at one of the main production facilities of the Mayak Production Association (reactor, radiochemical, and plutonium production plants) between 1948 and 1982, with follow-up until the end of 2018 (n=22,377; 25.4 % women). The average age at hiring was 24.11 (±7.13) years for men and 27.32 (±7.97) years for women (mean ± standard deviation (SD)). The average length of professional employment at the enterprise was 18.04 (±14.28) years. Mean total absorbed dose of external gamma radiation in the brain was 0.46 (±0.67) Gy for men and 0.36 (±0.56) Gy for women. Mean total absorbed dose of neutron radiation was 0.0016 (±0.0043) Gy and 0.0016 (±0.0050) Gy for men and women, respectively. Only confirmed cases of primary glaucoma (572 cases) were included into the analysis. Statistical analysis included estimation of the relative risk (RR) for categorized variables, adjusted for other factors. The excess relative risk per unit dose (ERR/Gy) was estimated using a linear dependence on the total external gamma radiation dose, adjusted (via stratification) for non-radiation factors (sex, attained age, birth cohort) and neutron radiation dose. Results: A statistically significant relative risk of normal tension glaucoma was found only in the group of workers who received external gamma radiation dose exceeding 1.0 Gy and made up 1.88 (95 % CI: 1.01–3.54; p = 0.047). Dose-response analysis in the cohort of chronically occupationally exposed workers revealed a statistically significant linear relationship between the incidence of normal tension glaucoma and the total dose of external gamma radiation (ERR/Gy = 0.53; 95 % CI: 0.01–1.68; p < 0.05). No statistically significant association was registered between the incidence of primary open-angle glaucoma or primary angle-closure glaucoma and the total dose of external gamma radiation in the studied cohort of workers.