re an 25 opia. Also notable was their tack 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 detachmentoccurred except in two people as a sequela of ocular surgery. Corneal scars, macular degeneration, vitreous floaters, and other degenerative intraocular conditions were seen in about the numbers expected in anvpart of the world. No Toxocara infestation or other intraocular 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 have residual 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 (congenitalnight blindness), congenital cataracts or glaucoma in the young or familial glaucomain older people, and colobomaofthe iris or posterior segment of the eye. On the other hand,certain congenital traits apparently 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 having corneas >14 mm in diameter. In ~5% of the people the retinal vessels showed increased tortuosity (corkscrew-like) and dilatation. This phenomenon has sometimes been foundassociated 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 chjldren 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 impairmentor 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 numberof people on Rongelap, and, thoughits distance from them precluded thermalinjuryto 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 sun rising in the west.” They probably did not see it at its greatest luminescence, when the damaging ocular effects occur, because this comes a fraction of a microsecond after detonation, so that at a distance of 100 miles the fireball would not yet have risen above the horizon. Also, at that distance the size of the image on the retina would be small. These factors probably explain why no one complained of blindness from seeing the fireball and no retinal scars have been found in any of the people. Ionizing 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 pene- tration makesit unlikely that the lens or retina received any significant dose from this source. During the two days before evacuation, many of the people complained of some itching and burning of the eyes with some lachrymation. These symptoms may have beenrelated to radiation from falloutin the eyes, but physical and chemicalirritation by the caustic fallout dust may have played an important part. 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 inflammationof the eyelids which may have been ducto beta irradiation. These lesions healed within several days. Corneal 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 duc to beta radiation and was possibly related to the bluish pigmentation notedin the nail beds. The latter disappeared whenthenail bed grew out several monthslater, but the corneal