BACKGROUND Colour vision is a function of three types of cone pigments present in the retina. Colour vision deficiency is an important disorder of vision that may pose a handicap to the performance of an affected individual. The prevalence of colour blindness varies in different geographical areas. The identification and estimation of the prevalence of colour vision deficiency in school-going children will help to educate and guide the caregivers to help the children in selecting their profession. This study was done to estimate the prevalence, sex distribution, and types of colour vision deficiency among school-going children of 5 to 15 years. METHODS A cross-sectional observational study was done among 500 students to evaluate the colour vision during the period from 1st January 2018 to 30th June 2019 at the Regional Institute of Ophthalmology, Kolkata. Ishihara’s pseudo isochromatic colour vision chart 38th edition was used to assess the school children for colour vision status. The children who were found to be colour blind were further classified into degree and types of colour vision deficiency. RESULTS A total of 500 students (250 male & 250 female) of surrounding schools, in the age group of 5 years to 15 years, were screened. 480 students (96 %) had normal colour vision while 20 (4 %) students were found to have defective colour vision. Prevalence (4 %) for colour blindness was found to be higher in males (3.6 %) than females (0.4 %). It was observed that out of 20 (4 %) colour-blind subjects 3.6 % were protanopes and 0.4 % were deuteranopes. CONCLUSIONS The present study shows the prevalence of colour blindness found to be quite low (4 %) and more common in males (3.6 %) in comparison to females (0.4 %). Protanomaly (3.6 %) was more common than deuteranomaly (0.4 %). KEYWORDS Colour Blindness, Protanomaly, Deuteranomaly, School Children

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