Masters Dissertations

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Browsing Masters Dissertations by Subject "Accommodation a Visual Acuity"

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    Visual acuity screening and the prevalence of refractive errows among primary school children in Dar es Salaam.
    (University of Dar es Salaam, 1998) Ngowi, Ida Medard
    A cross-sectional non-intervention community based study was conducted in Dar es Salaam, between January and February 1998. Two schools, Muhimbili and Mbagala were randomly selected. The aim of the study was to determine the prevalence of refractive errors among primary school children in Dar es Salaam and to propose a simple screening method for detecting poor vision. A total of 2600 primary school children were interviewed using a questionnaire. Visual acuity was screened by the proposed method and the standard Snellen E-Illiterate test. Re-testing by the use of the proposed screening method was performed to approximately 75% of the school children. Results showed that of the 2600 children studied 99.08% were Africans. 0.88% Arabs and 0.04% Indians. 57.5% were female and 42.5% were male. The prevalence of refractive error was 8.5%. Of these 9.6% were female and 6.9% were males. A higher prevalence of refractive errors was observed among the 10-14 years old children. This observation was due to unequal demographic distribution in age. In this study it was observed that environmental factors has no role in the development of refractive errors. The proposed screening test was found suitable for screening poor vision among primary school children. The proposed test was observed to have an acceptable sensitivity value to 49% and a high specificity value of 99%. The positive predictive value and the negative predictive value were 96% and 95% respectively. Re-testing showed approximately the same results and therefore proved the test to be reliable. This study determined the prevalence of refractive errors among school children in Muhimbili and Mbagala primary schools in Dar es Salam. It is recommended that a similar study be carried out involving several schools in Dar es Salaam in order to obtain a supportive data. Rural and urban areas could also be involved. It is also recommended that at the beginning of each year, schools children should be screened to detect those with poor vision and appropriate measures taken. The proposed method for screening proved to be cheaper, portable and furthermore the testing does not require a professional to be performed.