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L.T. Chylack, Jr., A.H. Feiveson, L.E. Peterson, F.K. Manuel, M.L. Wear, D. Hardy, L. Marak, W.H. Tung, E. Hernandez, F. Cucinotta; The NASA Study of Cataract in Astronauts (NASCA): Year–1 Data . Invest. Ophthalmol. Vis. Sci. 2006;47(13):4140.
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© ARVO (1962-2015); The Authors (2016-present)
NASCA is a 5–yr study of risk factors associated with cataract incidence and progression in US astronauts, military pilots, and ground–based controls (GBC). Risk factors studied include: space radiation exposure, nutrition, UV exposure, and age.
Areal extent of cortical (C), and posterior subcapsular (P) opacity and density of nuclear (N) opacity were assessed in Nidek EAS 1000 digital lens images. Nuclear color was graded with LOCS III. We used the Harvard Food Frequency Questionnaire (HFFQ). Lens–specific radiation exposures from space, medical sources, aviation training, and isotopes were incorporated. Statistical analysis used space radiation dose–response modeling of baseline prevalence of C, P, and N adjusted for age, nutrition, and solar exposure. Several within–astronaut and between–group dose–response models were analyzed. We modeled distribution of C area opaque as a skew–normal distribution and determined the statistical significance of age, space radiation exposure, and 106 nutritional variables on the location, spread, and skewness of the distribution. We modeled the area of P opacification with an ordered logit–regression and N density data at 3 loci with a beta distribution.
Complete data from 199 astronauts, 90 pilots, and 95 GBC were available after 1 yr. In our preliminary results baseline prevalences of C, N, and P among astronauts and pilots were significantly lower than in GBCs. For astronauts only, age, radiation, and sun exposure were statistically significantly associated with worsening, and α– and ß–carotene with amelioration, of C. For N age was the main explanatory variable for all loci. For astronauts only, space radiation had no effect on pixel density of the central N clear zone or the posterior embryonal nucleus, but it did have a small statistically significant effect (worsening) on the pixel density of the N anterior embryonal nucleus. Lutein had a strong protective effect at each of the three N loci. α– and ß–carotene produced similar results. Age was the only variable statistically significantly associated with extent of P.
Age was significantly associated with severity in C, P, and N. For astronauts only space radiation and UV exposure were significantly associated with worsening C and with opacification of the anterior embryonal nucleus. α– and ß–carotene and lutein had small beneficial effects on C and N opacification, respectively.
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