Abstract
Background: Human color vision is normally trichromatic in the sense that a suitable mixture of red,
green and blue lights can match any color that we can see. Color blindness occurs when one or more of
the cone types are absent, or present but defective. It is a common X-linked genetic disorder. However,
most of color blinds remain undetected due to absence of proper screening.
Objective: To determine the prevalence of congenital color blindness and identify the level of
awareness about their color vision defect among school children.
Design: This was a cross sectional study.
Setting: The study was conducted in five schools of Abeshge district Central Ethiopia among school
children in February 2009.
Materials and Methods: A total of 1040 male school children of grade 3 to 8 screened for color vision
defect using Ishihara’s pseudoisochromatic test 38 plate edition. The sociodemographic data and
results of color vision test and ocular examination collected using pretested structured questionnaire.
Data was entered and analyzed using SPSS statistical package version 15.0.
Results: A total of 1040 male school children were screened with a mean age of 12 ± 2.43 years. Among
these 44 cases (4.2%) (95% Confidence Interval 2.98 to5.42) were color blind. Of these 30 cases (2.89%)
involved deutan, 6 cases (0.58%) protan, 6 cases (0.58%) unclassified, and 2 cases (0.19%) of totally
color blind. All of the color blind subjects were not aware of their status of color vision.
Conclusion: The prevalence of congenital color blindness in this study is similar to the previous two
studies among Ethiopians. Cases of total color blindness among Ethiopians reported for the first time.
Early school screening for color vision defect is recommended.
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