Frequency of Color Blindness Among School Children in two Secondary Schools in Kirkos Sub- City of Addis Ababa, Ethiopia
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Date
2019-11-11
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Addis Ababa University
Abstract
In the human visual system, the eye receives physical stimuli in the form of light and sends these stimuli as electrical signals to the brain, which interprets them as images. In retina, there are two types of cells that detect light. They are called rods and cones. Rods detect only light and dark and are very sensitive to low light levels. Cone cells detect color and are concentrated near the center of our vision. There are three types’ cones that see color: red, green and blue. The brain uses input from these cone cells to determine color perception. Color blindness can happen when one or more of the color cone cells are absent, or not functioning, or detect a different color than it does normally. The main aim of the present study was to determine the frequency of color blindness among school children of two schools in Addis Ababa. The study was conducted from March 20 to June 06, 2019. Simple random sampling method was used to estimate the sample size. Accordingly, 1012 students from grade 9 and 10 of the two schools were participated in the study. Among these, 606 were females and 406 were males and their ages range from 14 to 20 years. Color vision was tested by using Ishihara 24 plates and subject were asked to seat in a room with sufficient light and read the figures/symbols on the plates from a computer/printed paper placed 75 cm away from the subject. The data were manually arranged and frequencies were calculated. Among the 1012 students tested, 22(2.17%) have color vision defect; these included 5(0.49%) females and 17(1.68%) males. Total colorblindness (achromatopsia) was the more frequent 10(0.99%) color vision defect observed. It was followed by deuteranopia 8(0.79%), protanopia 3(0.29%). It was observed that the prevalence of color blindness is higher in males than in females.
Key words: Color Vision Deficiency, Trichromat, Dichromat, Monochromat, protan, Deutan, Tritan, Ishihara,s color plates.
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Keywords
Color Vision Deficiency, Trichromat, Dichromat, Monochromat, Protan, Deutan, Tritan, Ishihara, S Color Plates