title: Radiation dose and cataract surgery incidence in atomic bomb survivors, 1986-2005.
abstract: OBJECTIVE
  To examine the incidence of clinically important cataracts in relation to lens radiation doses between 0 and approximately 3 Gy to address risks at relatively low brief doses.
  
  
  METHODS
  Informed consent was obtained, and human subjects procedures were approved by the ethical committee at the Radiation Effects Research Foundation. Cataract surgery incidence was documented for 6066 atomic bomb survivors during 1986-2005. Sixteen risk factors for cataract, such as smoking, hypertension, and corticosteroid use, were not confounders of the radiation effect on the basis of Cox regression analysis. Radiation dose-response analyses were performed for cataract surgery incidence by using Poisson regression analysis, adjusting for demographic variables and diabetes mellitus, and results were expressed as the excess relative risk (ERR) and the excess absolute risk (EAR) (ie, measures of how much radiation multiplies [ERR] or adds to [EAR] the risk in the unexposed group).
  
  
  RESULTS
  Of 6066 atomic bomb survivors, 1028 underwent a first cataract surgery during 1986-2005. The estimated threshold dose was 0.50 Gy (95% confidence interval [CI]: 0.10 Gy, 0.95 Gy) for the ERR model and 0.45 Gy (95% CI: 0.10 Gy, 1.05 Gy) for the EAR model. A linear-quadratic test for upward curvature did not show a significant quadratic effect for either the ERR or EAR model. The linear ERR model for a 70-year-old individual, exposed at age 20 years, showed a 0.32 (95% CI: 0.09, 0.53) [corrected] excess risk at 1 Gy. The ERR was highest for those who were young at exposure.
  
  
  CONCLUSIONS
  These data indicate a radiation effect for vision-impairing cataracts at doses less than 1 Gy. The evidence suggests that dose standards for protection of the eye from brief radiation exposures should be 0.5 Gy or less.
authors.affiliation: Department of Clinical Studies, Radiation Effects Research Foundation, 5-2 Hijiyama Park, Minami-ku, Hiroshima 732-0815, Japan. neriishi@rerf.or.jp
authors.forename: Kazuo
authors.initials: K
authors.lastname: Neriishi
authors.forename: Eiji
authors.initials: E
authors.lastname: Nakashima
authors.forename: Masazumi
authors.initials: M
authors.lastname: Akahoshi
authors.forename: Ayumi
authors.initials: A
authors.lastname: Hida
authors.forename: Eric J
authors.initials: EJ
authors.lastname: Grant
authors.forename: Naomi
authors.initials: N
authors.lastname: Masunari
authors.forename: Sachiyo
authors.initials: S
authors.lastname: Funamoto
authors.forename: Atsushi
authors.initials: A
authors.lastname: Minamoto
authors.forename: Saeko
authors.initials: S
authors.lastname: Fujiwara
authors.forename: Roy E
authors.initials: RE
authors.lastname: Shore
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D002386:Cataract / Q000453:epidemiology*; D002387:Cataract Extraction / Q000706:statistics & numerical data*; D004307:Dose-Response Relationship, Radiation; D005260:Female; D006801:Humans; D015994:Incidence; D007564:Japan / Q000453:epidemiology; D008297:Male; D008875:Middle Aged; D054043:Nuclear Weapons; D016012:Poisson Distribution; D016016:Proportional Hazards Models; D012307:Risk Factors; D017741:Survivors