Abstract:
Color blindness, or color vision deficiency (CVD), is the inability or decreased ability to
perceive color differences under normal lighting conditions. Human color vision is normally
trichromatic i.e. the mixture of red, green, and blue lights. Impaired color vision, in the case
of red-green color blindness, is genetically determined by X-linked recessive inheritance
and thus occurs mainly in males. The general objective of the study is to estimate the
frequency of Color Blindness among students and their Awareness about their color vision
status in six selected Primary schools in Haramaya, Awaday and Harar towns (two from
each town), Eastern Ethiopia. A total of 1158(male=female=579) school children of grade 3
to 8 were screened for color vision defect using Ishihara’s test 14 plate editions. Some
socio-demographic data of the participants such as age, grade, sex, self-declared ethnicity,
religion were also collected using questionnaire. Hardy–Weinberg method
(p2 + q
2 + 2pq = 1) was applied to calculate the expected genotype and allele frequencies in
females. Of the total 1158 participants 49(4.2%) were color deficient and 14 of them were
females (1.2%) and 35 (3.0%) were males. The larger proportion (3.0%) of the CVD
individuals were deutran while, 13(1.1%) were protan and 1(0.1%) was total color blind.The overall phenotypic frequency of color blindness in this study was: 2.3% among Oromo
male > among Oromo females 1.12% > among Harar males 0.7% > 0.00% among Amhara
males and Harar females. The highest frequency of allele X
A was found among Oromo
(0.989) and the least frequency of allele X
A was found among Harar (0.00) and the highest
Frequency of allele X
a were found among Oromo (0.011) the least Frequency of allele X
a
were found among Harar (0.00). This study indicated that all of the color blind subjects
were not aware of their color deficiency status. Further studies to be done to determine the
severity of color blindness using Ishihara is also recommended.
