New data on the vision of South American Indians.

A total of 466 males and 437 females from four Brazilian Indian tribes were tested for color blindness with Ishihara's plates. Defective persons were found in three of the four tribes, but when these and other groups are considered the evidence suggests that the frequency of this trait is lower among Amerindians than among Caucasian populations. Visual acuity tests were performed on 296 Yanomama Indians. Their visual acuity was apparently not as sharp as that of the Cayapo or Xavante. But the scarcity among the Yanomama of persons with serious visual impairment of subcutaneous nodules suggests that the focus of onchocerciasis discovered among them is of recent origin.