INCIDENCE OF COLOUR BLINDNESS IN INDIANS.

Abstract

NORMAL colour vision is of great importance for workers in many occupations, and those with defective colour vision should not be employed on tasks requiring good colour discrimination. Colour blindness is usually a congenital defect. Fran9ois and Verriest (1957a) state that colour vision defects in man are due to accidental mutations rather than to atavism. Acquired colour blindness has been reported by Francois and Verriest (1957b) in cases of aphakia, senile macular degeneration, progressive myopia, retinal detachment, and chorio-retinitis. Statistics on the incidence of colour blindness in the general population are few. Frangois, Verriest, Mortier, and Vanderdonck (1957) examined 1,243 young male students and found that 128 (8 per cent.) were colour blind. Montauffier, Riu, Camo, and Hebert (1958) found that 7 per cent. of 517 navy personnel were colour blind. In the series of 500 people Belcher, Greenshields, and Wrights (1958) found 38 (7-6 per cent.) colour blind. The incidence of colour blindness in races other than European has not been widely studied. Rivers (1901) investigated a local population in Upper Egypt, and also carried out a survey in Papunas and Todas (Rivers, 1904) where 10 per cent. of the population was colour blind. Geddes (1946) examined 148 Fijian natives and found 12 (8-1 per cent.) colour blind. Simon (1951) examined 537 Buganda Africans and found only 1 86 per cent. to be colour blind. Mann and Turner (1956) found that 1 9 per cent. of male and 0-031 per cent. of female aboriginals were colour blind, but the figures for white Australians were higher-7-3 per cent. for males and 0-61 per cent. for females. Anomalies of colour vision in Japanese children have been reported by Nakajima, Ichikawa, Nakagawa, Majima, and Watanabe (1960), who examined 3,033 children, ofwhom 81 (77 males and 4 females) were defective. These previous studies are summarized in Table I (overleaf). No assessment of the incidence of colour blindness in an Indian population has so far been made.