FREQUENCY OF COLOR BLINDNESS AMONG STUDENTS AND THIER AWARENESS ABOUT THEIR STATUS IN SELECTED PRIMARY SCHOOLS IN HARAMAYA, AWADAY AND HARAR TOWNS, EASTERN ETHIOPIA

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.