Vision screening tests within the limits of industrial medicine examinations, 
together with physical examinations, were done on human individuals by means of 
pseudo-isochromatic charts in order to detect "red-green blindness". The tests 
were carried out on 1589 individuals (males and females) from 10 medium-scale 
plants of the Saarbrücken area (Federal Republic of Germany). The results 
obtained from male individuals by 919 Ishihara-tests were only considered, 
categorized and graphically represented according to their age groups. The data 
have been collected from the cases examined mostly between the years 1976 to 
1977. About 1500 cases were examined per year. Because the samples were not 
selected at random, one has to be cautious with regard to the statistical 
interpretations of the results. However, due to the large number of cases 
included in the study, it can be statistically represented. The histogram 
illustrating the distribution of colour-vision deficiency, according to each age 
group, shows the highest peak at an age range of 30 to 35 years. This indicates 
that a considerable number of cases with colour-vision deficiency was discovered 
late. The individuals have to be early examined by school physicians, house 
physicians, occupational physicians, internists or ophthalmologists with this 
colour-vision screening test, before they enter professional life. Some 
symptomatical complexes of internal diseases and human genetics, i.e. related to 
"colour-vision blindness" are also emphasized hemophilia and hemolytic anemia 
due to glucose-6-phosphate dehydrogenase deficiency.