Prevalence and allele frequency of Congenital Colour Vision Deficiency (CCVD) among students at Hawassa University, Ethiopia

Zelalem Gebremariam Tolesa,Reta Gutema Mitiku,Bekele Serbessa Tolera

doi:10.1186/s42506-020-00037-y

Abstract

BackgroundThe prevalence of congenital colour vision deficiency (CCVD) varies from race to race and differs in different geographic regions. Colour vision deficiency or colour blindness, is the inability or decreased ability of discriminating certain colour combinations and colour differences under normal lighting conditions. This study aimed to determine the prevalence of congenital colour vision deficiency among students at Hawassa University.MethodsA cross-sectional survey was employed involving 4004 students (females = 1171 and males = 2833) from four campuses, namely, Institutes of Technology, College of Health Science and Medicine, College of Agriculture and Main Campus. The Ishihara pseudo-isochromatic 24 plate edition was used to test the colour vision of students under natural day light condition.ResultsThe prevalence of CCVD in the present study was 2.85%. A hundred and six (3.75%) males and eight (0.68%) females were affected with congenital colour vision deficiency. The frequencies of achromacy, deutan and protan in male subjects were 4 (0.14%), 82 (2.89%), and 24 (0.85%), respectively. Deutan was highest among students of Amhara ethnic origin (38, 2.51%), but the frequency of protan was highest amongst Oromo students (10, 0.8%).Conclusion and recommendationsThe overall prevalence of CCVD found in the present study was lower compared to the previous studies done in Ethiopia. There was clear variation in the prevalence of colour vision deficiency among students of various ethnic groups. Proper screening, education and counseling are needed to minimize impacts of CCVD in the country, and can also be beneficial for the affected subject in tackling difficulties in everyday work and for proper choice of future profession.

Highlights

Normal colour vision in humans is mediated by the three classes of cone photoreceptors: the blue or shortwave-sensitive (S), the green or middle-wave-sensitive (M), and red or longwave-sensitive (L) [1]
Of the total study subjects, 114 (2.85%; 95% CI: 2.33 to 3.37) had congenital colour vision deficiency, including 106 males and 8 females (Table 1)
Deutan was highest amongst students of Amhara ethnic origin 38 (2.51%), but the frequency of protan was highest amongst Oromo students 10 (0.87%)

Summary

Introduction

Normal colour vision in humans is mediated by the three classes of cone photoreceptors (trichromatic colour vision): the blue or shortwave-sensitive (S), the green or middle-wave-sensitive (M), and red or longwave-sensitive (L) [1]. Colour vision deficiency (CVD), is the inability or decreased ability to discriminate certain colour combinations and colour differences under normal lighting conditions. The prevalence of colour congenital blindness varies from race to race and differs in different geographic areas. The prevalence of CCVDs varies among females from population to population, for example, 0.46 % among the Basque population (Spain) [19], 0.75% in Saudi Arabia [12], and 0.93% in Qazvin (Iran) [20]. The prevalence of congenital colour vision deficiency (CCVD) varies from race to race and differs in different geographic regions. Colour vision deficiency or colour blindness, is the inability or decreased ability of discriminating certain colour combinations and colour differences under normal lighting conditions.

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