A study of the Prevalence of Color Blindness in Yazd Railway Staff

Color blindness is one of the common genetic disorders in all human communities. The genes which specify the red and green sensitive photopigments are located on the X chromosomes within the Xq28 band. Abnormalities are inherited as an X-linked recessive trait. This results in a much higher prevalence of red - green color deficiency in males than in females. It, s prevalence rate in human communities is a bout 8% and for females about 0.5 %.Due to the importance of color vision for locomotive drivers,358 railway staff and locomotive drivers in Yazd were randomly selected and tested for red - green color blindness and visual acuity. To do this,a questionnaire including information on age, level of education, occupation, smoking, visual acuity, color blindness and awareness of color blindness was prepared. The 38-plates edition of the Ishihara test was used to examine red - green color blindness and Snellen chart was also used to check visual acuity.Of the subjects27 (7.54%)showed color blindness, 6 of them being locomotive drivers.Three showed protanopia, 5 protanomaly, 4 deuteranopia and 15 deuteranomaly. The prevalence of color blindness showed no correlation with visual acuity, smoking, age and the level of education (p-value > /05). The frequency distribution of having a good knowledge, partial knowledge and lack of knowledge on their color blindness was 18.52%, 48.15% and 33.33% respectively.Prevalence of red-green color blindness in rail way staff (7.54%) is comparable to other communities (2 -10 %).