Ugandan colorblinds revisited

A rapid examination with the Ishihara plates of secondary schoolboys in Kampala was followed by anomaloscopy of those who failed or hesitated on the screening test. The average rate of all red‐green deficiencies among 1626 lads of various Bantu and Nilotic origins is 3.9%. This is twice a previous estimate, obtained by methods which apparently failed to detect anomalous trichromates. An exceptionally high rate of defects (13.8%) and particularly of deuteranopia (7.3%) was found in a sample of 261 Ismailites. The average rate of all defects among 288 boys of other Indian and Pakistani communities is 4.5%, which is not significantly different from the rate found among Africans. Deutan/protan ratio among indigenous Ugandan colorblinds is 1.07, considerably lower than the ratio of Europeans and Asians. Africans' rate of dichromatic red‐green blindness, 2.5%, is at about the average found elsewhere.