Frequency of Colour Blindness and Its Genetic Underpinning Among Male Students in Ogun State Tertiary Institutions

Red-green colour blindness, caused by mutations in the OPN1LW and OPN1MW genes on the X chromosome, is the most common human visual impairment with a population frequency that varies by ethnicity and sex. Given its X-linked recessive inheritance, males are predominantly affected. This study determined the frequency of colour blindness among male undergraduate students in selected tertiary institutions in Ogun State, South West Nigeria. A total of 500 male students from three institutions (a university, a polytechnic, and a college of education) were screened using the Ishihara pseudoisochromatic plates, a validated and widely used clinical tool. Those identified as colour-blind were further assessed with the Farnsworth-Munsell 100 Hue Test to determine deficiency type and severity. Participants completed a questionnaire addressing awareness of their condition and functional implications in their studies and daily life. A prevalence rate consistent with African population estimates was observed, with protan defects (red sensitivity) being more frequent than deutan defects (green sensitivity). Many affected students were unaware of their condition. Recommendations include incorporating colour vision screening into university health assessments and adapting course materials for colour-blind students. Keywords: colour blindness, OPN1LW, X-linked, Ogun State, colour vision deficiency