25 opia. Also notable was their lack of retinoblasto- mas, malignant melanomasof the choroid, and basal cell carcinomaofthe eyelids. Ocular pathology caused by herpes simplex or zoster viruses was not seen. No cases of retinal detachment occurred except in two people as a sequela of ocular surgery. Corneal scars, macular degeneration, vitreous floaters, and other degenerative intraocular condiuons were seen in about the numbers expected in anypart of the world. No Toxocara infestation or otherintraocular parasites have been encountered, and no ocular involvement by the parasites Onchocerca orfilaria has been seen. In the one case of inactive leprosy on Rongelap noocularlesions 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 andfa- milial ocular diseases found in Americans were not seen in the Marshallese, such as ocular dystro- phias, retinitis pigmentosa (congenital night blindness), congenital cataracts or glaucoma in the youngor familial glaucoma in older people, and colobomaof the iris or posterior segment of the eye. On the other hand, certain congenital traits apparentiy peculiar to this race were noted. The average size of the corneas is greater than in the U:S., more than 60% of the people examined hav- ing corneas >>14 mm in diameter. In ~5% of the people the retinal vessels showed increased tortu- ositv (corkscrew-like) and dilatation. This phenom- enon has sometimesbeen 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 of the eyelids, forehead, and face. It has been several years since night vision impairment or molluscum has beenseen. 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 produce retinal damage with scarring and possible blindness.33.34 The Bravo fireball was observed by a small number of people on Rongelap,and, thoughits distance from them precluded thermalinjury to the skin from longwave(visible and infrared) light, injury to the retina 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 oculareffects occur, because this comes a fraction of a microsecondafter detonation, so that at a distance of 100 miles the fireball would not vet have risen above the horizon. Also, at that dis- tance the size of the image on the retina would be small. These factors probably explain why no one complained of blindness from seeing thefireball and noretinal scars have been found in anyof the people. fonizing radiation. The fallout on Rongelapresulted in a gamma dose of 175 rads to the whole body including the eyes. Beta rays from fallout deposited on the ground and contaminating the eyes resulted in some superficial exposure of the lids, conjunctiva, and cornea, but their low penetration makes it unlikely that the lens or retina re- ceived anysignificant dose from this source. Dur- ing the two days before evacuation, manyofthe people complained of someitching and burningof the eyes with some lachrymation. These symptoms may havebeenrelated to radiation from fallout in the eyes, but physical and chemicalirritation by the caustic fallout dust may have played an im- portant part. Internal absorption of radionuclides probably did not contribute to the radiation dose to the eyes. Conjunctwitis. 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 inflammationof the eyelids which may have been dueto betairradiation. These lesions healed within several days. Corneal pigmentatwn. Beginning at about 2 months post exposure, in some people a pigmented line was noted in 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 tength. This may have been dueto beta radiation and was possibly related to the bluish pigmentation noted in the nail beds. The latter disappeared when the nail bed grew out several monthslater, but the corneal