Technical Report No. 18-91
Radiation-related ophthalmologic changes and aging among the atomic bomb survivors: A re-analysis
Otake M, Finch SC, Choshi K, Takaku I, Mishima H, Takase TEditor’s note: A publication based on this report was published in Radiat Res 131:315-24, 1992.
Summary
The relationship of ionizing radiation to the age-related ophthalmologic findings of the 1978-80 ophthalmologic examination of the atomic bomb (A-bomb) survivors of Hiroshima and Nagasaki has been reanalyzed using Dosimetry System 1986 eye organ dose estimates. The main purpose of this re-evaluation was to determine whether age and radiation exposure have an additive, synergistic, or antagonistic effect on ophthalmologic changes. The focus of this study is limited to axial opacities and posterior subcapsular changes, for which a definite radiation-induced effect has been observed among the A-bomb survivors.
The best model fitting axial opacities gives a significant positive effect for both linear dose-response and linear age-related regression coefficients and a significant negative effect for an interaction between radiation dose and age. Such a negative interaction implies an antagonistic effect in that the relative risks with relation to radiation doses decrease with increasing age. The log relative risks for persons 40, 50, 60, and 70 yr old at the time of examination (ATE) were 8.2-, 6.4-, 4.6-, and 2.8-fold higher, respectively, than those in persons 80 yr old ATE. The relative risks for axial opacities in persons 40 yr old ATE were 1.5 at 1 Sv, 2.3 at 2 Sv, 3.4 at 3 Sv, and 7.8 at 5 Sv, but the risks in persons 80 yr old ATE were 1.0, 1.1, 1.2, and 1.3, respectively. This phenomenon suggests that the lenses of younger persons are more sensitive to radiation than are those of older persons. However, the best-fitting relationship for posterior subcapsular changes suggested a linear-quadratic dose response and linear age-related effects. The quadratic estimate of radiation dose squared showed a highly significant effect with a negative trend, but the negative quadratic estimate was so extremely small it had almost no contributive value within an appropriative dose area. These data suggest an additive relationship between aging and radiation for the induction of posterior subcapsular changes, and they also indicate that there is no distinct evidence of a radiation-induced aging effect. The radiation-related relative risks increase with a log linearity: 1.7 at 1 Sv, 3.0 at 2 Sv, 5.1 at 3 Sv, and 14.3 at 5 Sv.
The decrease of visual acuity and accommodation with increasing age were comparable in both exposed and control subjects, with age-related visual acuity decreasing more than accommodation.
The relationship of ionizing radiation to the age-related ophthalmologic findings of the 1978-80 ophthalmologic examination of the atomic bomb (A-bomb) survivors of Hiroshima and Nagasaki has been reanalyzed using Dosimetry System 1986 eye organ dose estimates. The main purpose of this re-evaluation was to determine whether age and radiation exposure have an additive, synergistic, or antagonistic effect on ophthalmologic changes. The focus of this study is limited to axial opacities and posterior subcapsular changes, for which a definite radiation-induced effect has been observed among the A-bomb survivors.
The best model fitting axial opacities gives a significant positive effect for both linear dose-response and linear age-related regression coefficients and a significant negative effect for an interaction between radiation dose and age. Such a negative interaction implies an antagonistic effect in that the relative risks with relation to radiation doses decrease with increasing age. The log relative risks for persons 40, 50, 60, and 70 yr old at the time of examination (ATE) were 8.2-, 6.4-, 4.6-, and 2.8-fold higher, respectively, than those in persons 80 yr old ATE. The relative risks for axial opacities in persons 40 yr old ATE were 1.5 at 1 Sv, 2.3 at 2 Sv, 3.4 at 3 Sv, and 7.8 at 5 Sv, but the risks in persons 80 yr old ATE were 1.0, 1.1, 1.2, and 1.3, respectively. This phenomenon suggests that the lenses of younger persons are more sensitive to radiation than are those of older persons. However, the best-fitting relationship for posterior subcapsular changes suggested a linear-quadratic dose response and linear age-related effects. The quadratic estimate of radiation dose squared showed a highly significant effect with a negative trend, but the negative quadratic estimate was so extremely small it had almost no contributive value within an appropriative dose area. These data suggest an additive relationship between aging and radiation for the induction of posterior subcapsular changes, and they also indicate that there is no distinct evidence of a radiation-induced aging effect. The radiation-related relative risks increase with a log linearity: 1.7 at 1 Sv, 3.0 at 2 Sv, 5.1 at 3 Sv, and 14.3 at 5 Sv.
The decrease of visual acuity and accommodation with increasing age were comparable in both exposed and control subjects, with age-related visual acuity decreasing more than accommodation.