16 plaque, greenish and bluish hues were noted, hence the name polychromatic sheen. These lens opacities are not comparable to the subcapsular flecks of the lens recorded in the 1969 survey and described below. Whetherthe polychromatic sheen seen following irradiation has a unique and specific character is still a debatable question. Someinvestigators contend that similar appearing changes can be detected in patients with retinitis pigmentosa and the early stages of cataracts, which might be a complication ofendogenousocular systemic disease. Such polychromatic sheens were seen in 10% of the unirradiated Rongelap group and 16% of the exposed group. Again, the difference is thought to be too small to reflect irradiation exposure with any degree of certainty, paricularly in view of the slightly greater numberof older people in the exposed group. The incidence oflenticular opacities was also slightly greater in the exposed group than in the unexposed group. Corneal pigmentation, noted in previous examinations, was noted in only one case in the 1967 survey. This pigmentation was characterized by a fine, dark, linear sheet of pigmentlying close to or on Bowman’s membranein the horizontal axis, between the limbus and pupillary edge. Possibly these changes may have been iduced by beta radiation from contaminated material whichcollected on the marginsof the eyelids at the time of the fallout. Several findings maybe residuals of the 1963 poliomyelitis epidemic. There were twocases of 7th nerve weakness involving the eyelids and an increase in the numberof cases of esqphoria.and esotropia (ocular muscle imbalances) in postpoliomyelitis cases. In the 1967 surveyit was gratifying to find only one possible case of poor night vision attributable to inadequate vitamin A intake. This indicated improved nutrition with regard to vitamin (yellow fruits and vegetables: squash, papaya, bananas, pandanus, yams,etc.). RESULTS OF SPLIT-LAMP MICROSCOPIC EXAMINATIONS,* 1969 SURVEY ** Study of theMarshallese persons exposed to radioactive fallout in 1954 for effects within the *By Dr. John L. Bateman, a memberofthe survey team. **Research supported in part by Grant RH99, Division of Radiologica) Health, Bureau ofState Services, U.S. Public Health Service. 903273 optic lens is of particular interest because (1) a broad span of ages was involved,and (2) the highest gamma exposure was slightly less than the lowest (radiotherapeutic) exposure at which Merriam found an effect on the lens.19 The 1967 lens examinations of the Marshallese had shown the incidénce of polychromatic sheen and lenticular opacities to be slightly higher in the exposed than in the nonexposed population. The differences were not thoughtto be significant, and the higher mean age of those exposed was pointed out (see preceding section). The subjective nature of observations of the lens usually made with theslit-lamp microscope argues for serial examinations with increasing time post irradiation, because slight differences between groups in one examination may becomesignificant with multiple examinations. A further obvious value to serial examinations is that of following the time course of lens changes within and between groups. (In a nonirradiated population, an approximate time course of lens changes may be derived by a single examination of individuals covering a broad spanof ages.) Assuming aninfluence of age, the status of an irradiated lens will depend on three primary factors: (1) the radiation characteristics (dose, quality, and doserate), (2) the age of the individual at exposure, and (3) the interval between irradiation and examination.For a radiation accident involving a single (relatively brief) exposure, a subsequent single examination can provide only one point on the time course of lens change at each age involved. The Marshallese experience provided an adequate numberof control individuals covering a broad span ofages, a lesser numberof individuals exposed to 175 rads, and insufficient numbers (for meaningful comparison) in lower exposure groups (doses of 14 or 70 rads). Conclusions from this examination must therefore be limited to status of the nonirradiated lens as a function of age, and age-specific comparisons between lenses in these people andin those exposed to 175 rads L5 years previously. It was intended during the 1969 medical survey to determine quantitatively the minutediscrete opacities in the anterior and posterior subcapsular regions, which appearsimilar to those that can be found in the posterior subcapsular region in the lens of the mouse (see Figure 17), and which may represent short defective portions of single lens fibers (see Figure 18). These defects are present in nonexpo been for mice exp Methods Shit-la dilatatio: made of as follow 41 perso sons; no unaware longed u general 312x_ lens, a: photog counts (flecks project Counts - subcapst one-half tion was flex as th the cour during c: effective] and exte nucleus. Eight. of advar corneal c