25 opia. Also notable was their lack of retinoblastomas, malignant melanomasof the choroid, and basal cell carcinomaofthe eyelids. Ocular pathology caused by herpes simplex or zoster viruses was not seen. Nocases of retinal detachment occurred except in two people as a sequela of ocular surgery. Corneal scars, macular degeneration, vitreous floaters, and other degenerative intraocular condi- tions were seen in about the numbers expected in any part of the world. No TJoxocava infestation or other intraocular parasites have been encountered, and no ocular involvement by the parasites Onchocerca or filaria has been seen. In the one case of inactive leprosy on Rongelap no ocularlesions have been noted. Some people haveresidual scars of yaws, but no active lesions have been seen dur- ing the 20-year period. Most of the congenital malformations andfamilial ocular diseases found in Americans were not seen in the Marshallese, such as ocular dystro- phias,retinitis pigmentosa (congenital nightblind- ness), congenital cataracts or glaucoma in the youngor familial glaucomain older people, and coloboma ofthe iris or posterior segmentof the eye. On the other hand, certain congenitaltraits apparently peculiar to this race were noted. The average size of the corneasis greater than in the U.S., more than 60% ofthe people examined having corneas >14 mm in diameter. In ~5% of the people the retinal vessels showed increased tortu- osity (corkscrew-like) and dilatation. This phenom- enon has sometimes been found associated with the sickle cell trait, but the latter has not been noted in the Marshallese. Dietetic and hygienic conditions in the Marshall Islands have improved over the 20 years of this study. In earlier years, poor night vision in children due to vitamin A deficiency was occasionally found, and molluscum contagiosum was seen more frequently; also lesions involving the skin ofthe eyelids, forehead, and face. It has been several years since night vision impairment or molluscum has been seen. 2. Possible Radiation Effects Both the detonation in March 1954 andtheresulting fallout gave rise to several types of radiation that might cause Injury to the eyes. Longwave radiation. Direct observation with the naked eye of the fireball of an atomic bomb detonation is known to produceretinal damage with scarring and possible blindness.33:34 The Bravo fireball was observed by a small numberofpeople on Rongelap,and, thoughits distance from them precluded thermalinjury to the skin from longwave(visible and infrared)light, injury to theretina must be considered. The fireball was described by the Rongelap people as appearing“like the sunrising in the west.”’ They probably did not see it at its greatest luminescence, when the dam- aging ocular effects occur, because this comes a fraction of a microsecondafter detonation, so that at a distance of 100 miles the fireball would not yet have risen above the horizon. Also, at that dis- tance thesize of the image on the retina would be small. These factors probably explain why no one complained of blindness from seeing the fireball and noretinal scars have been foundin any of the people. Ionizing radiation. The fallout on Rongelapresulted in a gammadoseof 175 rads to the whole body including the eyes. Beta rays from fallout deposited on the ground and contaminating the eyes resulted in somesuperficial exposure of the lids, conjunctiva, and cornea, but their low pene- tration makesit unlikely that the lens orretina re- ceived anysignificant dose from this source. Dur- ing the two days before evacuation, many of the people complained of some itching and burning of the eyes with some lachrymation. These symptoms may havebeenrelated to radiation from fallout in the eyes, but physical and chemical irritation by the caustic fallout dust may have played an importantpart. Internal absorption of radionuclides probably did not contribute to the radiation dose to the eyes. Conjunctivitis. The burning and lachrymation disappeared by the time the people were evacuated to Kwajalein Island. However, at the time of developmentof beta burns, about 2 weeks after exposure, two men developed conjunctivitis and inflammation ofthe eyelids which may have been dueto betairradiation. These lesions healed within several days. Comeal pigmentation. Beginning at about 2 months post exposure, in some people a pigmentedline was notedin the corneaat the limbusin the horizontal axis of the palpebral fissure, which appeared to be below the surface of the epithelium. It varied from 0.5 to 2 mm in length. This may have been dueto beta radiation and waspossibly related to the bluish pigmentation noted in the nail beds. The latter disappeared whenthe nail bed grew out several monthslater, but the corneal