Prevalence of Congenital Colour Vision Deficiency in Nigerians Living in Ugep, Cross River State

Colour vision deficiency and colour vision blindness are synonymous terms describing poor colour discrimination by the visual senses. Nowadays, screening for these disorders is an established practice, so that those affected can be advised about occupational preclusions. Since population based study on the broader impact of colour vision defects is limited, this study was undertaken in Ugep, a rural community in cross river state of Nigeria. Using the cluster sampling technique, a convenient sample of 1500 males and females (of between 10-60 years) were selected. Plates 1-17 of the 2008 edition of the Ishihara’s colour album were then administered to the subjects in rooms brightly illuminated by day light. Subjects were then screened with Plates 1, 3, 5, 13 and 15. Study reveals that, the prevalence of congenital colour vision deficiency in Nigerians living in Ugep is 1.8% (28 of every 1500 subjects), while that of total colour blindness was barely 0.2%. Gender distribution of colour blindness appeared in about 2.8% of sampled male subjects, and 0.7% of sampled female subjects, indicating a significantly greater frequency in males than the females. Distribution of colour blindness by age revealed no sequence between age and the defect as p < 0.001, df=1. Population based screening for colour vision deficiency is recommended for helpful prevocational counselling.