16 plaque, greenish and bluish hues wete noted, optic. lengis of particutar interest ‘because (1) a hence the name polychromatic sheen. These lens \.= broad span ofages was involved,and (2) the highopacities are not comparable to the subcapsulae~ est gammaexposure was slightly /ess than the lowest (radiothérapeutic}exposure |at which Merriam flecks of the lens recorded in the 1969 sii#vey and described below. Whetherthe polychromatic sheenseen follow- ing irradiation has a unique and-specific character is still a debatable question. Some investigators found an‘effeet on thelens.!9 The 1967 lens exy aminations efthe Marshallese had-shownzthe incidence ofpolychromatic sheen ard lenticular oplicities Be té te slightly higher in the exposed than in the nonexposed population. The differences were not thoughtto. be significant,Fagthe higher contend that similar appearing changes can be detected in patients with rgtinitis pigmentosa ond the early stages of cataracts, which migl mean age of those expdsadwas pointedout(see complication afendogenous ocularsystemic preceding section). we z -.. The subjective natige of‘observations‘of the lens Such polychromatic#heens were seen"easdO% af the unirradiated Rongelap group and £6%of the usually made with the slit-lamp microscope argues exposed group. Again, the differencesoar " for serial?examinations withincreasing time post a. be too small to reflectirradiation exposure-ggth any degreeof certainty, paricularly im view e.slightly greater numberof older in theex- catradiation, because slightdifferences between +s ee ~ |gousin one examination may becomesignificant - withemultiple examinations. A further obvious posed group. Theincidence of lenticular.opacities_ value to serial examinations is that of following the wasalso slightly fin the exposed group th ume course of lens changes within and between in the unexposed’group. a groups. (In a nonirradiated population, an apCorneal pigmentationnotediin previous exproximate time course of lens changes may be ~ aminations, was noted in only-one case in the 1967 derived by a single examination of individuals survey. This pigmentation was characterized by covering a broad span of ages.) Assuming an ina fine, dark, linear sheet of pigment lying close to fluence of age, the status of an irradiated lens will or on Bowman’s membranein the horizontalaxis, dependon three primaryfactors: (1) the radiation between the limbus and pupillary edge. Possibly characteristics (dose, quality, and dose rate), (2) these changes may have been iduced by beta the age of the individual at exposure, and (3) the radiation from contaminated material whichcolinterval between irradiation and examination. For lected on the margins of the eyelids at the time of 1 single(relatively the fallout. e Lamination Several findings mayberesiduals of the 1963 can:provide glyone soaof ondighestinhe courte.of poliomyelitis epidemic. There were two cases of lens ¢ha atonealaape vilved. 7th nerve weakness involving the eyelids and an Fhe] ershallese experienge"provided an.ade! increase in the numberofcases of esophoria and quategiumber of control individyals qo esotropia (ocular muscle imbalances) in post- poliomyelitis cases. In the 1967 surveyit was gratifying to find only one possible case of poor night vision attributable broad’spanafages,a lesser number ind id: to inadequatevitamin A intake. This indicated improved ny#reemewithregard to vitamin A (yel- low fruits ai és. squash, papaya, bananas, pandanus, valind, i ate = : aeofae+"“am )_MICROSCOPIC 1969 SURVEY** ey, + Study of theMarshgliese ing exposed to radioactive fallout in:1954for,effects within the *Byv Dr. John L. Bateman, a memberof the survey team. **Research supported in part by Grant RH99, Division of Radiological Health, Bureauof State Services, U.S. Public Health Service. found in the posterior“subcapsular region in the lens of the mouse (see Figure 17), and which may represent short defective portionsof single lens fibers (see Figure 18). These defects are present in