RERF Report No. 8-12

A research paper published in Radiation Research§“Glaucoma in Atomic Bomb Survivors”
Kiuchi Y, Yokoyama T, Takamatsu M, Tsuiki E, Uematsu M, Kinoshita H, Kumagami T,Kitaoka T, Minamoto A, Neriishi K, Nakashima E, Khattree R, Hida A, Fujiwara S, Akahoshi M
Radiat Res 2013 (October); 180(4):422–30 (doi: 10.1667/RR3273.2)

Study Findings
A previous paper reported that glaucoma incidence in the Adult Health Study (AHS), basedon medical history information, decreased with increasing atomic-bomb radiation dose. Thisfinding prompted the conduct of a cross-sectional glaucoma study based on systematic
ophthalmologic examinations. The study’s results suggested that the prevalence ofnormal-tension glaucoma, but not glaucoma with elevated eye pressure, may have increased
with A-bomb radiation dose. The estimated odds ratio at 1 Gy was 1.31 (95% confidenceinterval: 1.11–1.53, P = 0.001) for normal tension glaucoma. However, uncertainties exist in theresults because of the study’s low participation rate and the resulting possibility of selection
biases. The findings therefore should be interpreted cautiously until confirmed by other studies.
Explanation
While glaucoma has been found in 7–11% of patients as a complication of high radiationdose (e.g., radiotherapy), it is not understood whether radiation at low-to-moderate doses gives
rise to glaucoma. Systematic ophthalmologic examinations were conducted to evaluate thepossibility of excess glaucoma cases in relation to A-bomb radiation exposure.
1. Study purpose
To elucidate the association between glaucoma prevalence and A-bomb radiation, taking
other potential risk factors into consideration.
2. Subjects and methods
Of the 2,699 people who underwent health examinations in the AHS clinical program
between October 2006 and September 2008, the prevalence of glaucoma in relation to estimatedA-bomb doses was analyzed among the 1,589 people who participated in the glaucoma study.
However, the low participation rate (59%) introduced more uncertainty into the results and thepotential for selection biases. Upon conducting medical interviews and ophthalmologic
examinations, individuals with an indication of ocular disease, including glaucoma, werereferred to local medical institutions for more comprehensive evaluations. Glaucoma wasdiagnosed by glaucoma specialists on the basis of specific changes in the optic nerve head,visual field test results, and other related ocular findings.
3. Results
Of the 1,589 people, a total of 284 (17.9%) individuals were diagnosed as having glaucoma
in one or both eyes: 36 (2.3%) primary open-angle glaucoma cases (intraocular pressure ≥21mmHg), 226 (14.2%) normal-tension glaucoma cases, and 25 (1.6%) primary closed-angle
glaucoma cases. Logistic regression analysis with adjustment for gender, age, city, cataract
surgery, and diabetes mellitus, revealed an estimated odds ratio at 1 Gy of 1.31 (95% confidence
interval: 1.11–1.53, P = 0.001) for normal-tension glaucoma, but no association with radiationdose was observed for the other types of glaucoma.
4. Conclusion
This study’s findings suggest that the prevalence of normal-tension glaucoma may increase
with A-bomb radiation dose. However, the low participation rate in the study and possible
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RERF Report No. 8-12potential for selection biases introduced as a result warrant a cautious interpretation of theseresults.
5. Significance of this study and tasks aheadThis study, based on diagnoses made by ophthalmologists, suggests that normal tension
glaucoma may increase with A-bomb radiation dose. However, this finding must be confirmed
by other studies, and an epidemiological study that minimizes uncertainties and potential
selection biases needs to be conducted. If the association is confirmed, then studies could be
pursued of possible underlying biological mechanisms.

The Radiation Effects Research Foundation has studied A-bomb survivors in Hiroshima and Nagasaki
for more than 60 years. RERF’s research achievements are considered the principal scientific basis forradiation risk assessment by the United Nations Scientific Committee on the Effects of Atomic Radiation(UNSCEAR) and for recommendations regarding radiation protection standards by the International
Commission on Radiological Protection (ICRP).
§Radiation Research, which is an official monthly journal of the Radiation Research Society, publishes
original, peer-reviewed papers and review articles on radiation effects and related issues in the fields ofphysics, chemistry, biology, and medicine. (Impact factor in 2012: 2.698)

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