Background: Trachoma is the leading cause of infectious eye disease that leads to blindness. Continuous re-infection by the bacteria, Chlamydia trachomatis, leads to scarring of the cornea and subsequently to blindness. It is commonly found in the poorest and remotest part of Africa, Asia, Latin America and Mid-east, where hygienic conditions are also poorer. The Alliance for the Global Elimination of Blinding Trachoma by the year 2020 (GET 2020) was launched by World Health Organization (WHO) with the main aim of eliminating trachoma as a public health problem globally by year 2020. The Alliance funded Sightsavers, as part of the strategy to meet this target, to set up the Global Trachoma Mapping Project (GTMP) which was to map all endemic places for intervention through a population-based prevalence survey. There are five main signs of the disease and the number of people affected by each sign explains the magnitude and the intervention needed in that population. WHO recommends the active trachoma survey in children age 1-9 years and the blinding signs in adults' age 15 years and above. More researches, that establish quicker means of intervention for the endemic trachoma areas, are needed using the GTMP data in order to meet the year 2020 target. Methods: Baseline data from the Global Trachoma Mapping Project (GTMP) was used as a secondary dataset for this research. All eligible regions in Ethiopia were included. The GTMP teams conducted surveys in seven regions. All age groups were included, but for the purpose of planning, the study assessed TF in children age 1-9 years and TT in adults age 15 years and above. The prevalence of TF in children and TT in adults are indicators for programme decision making for intervention and establishing the relationship between them would aid in the intervention. The relationship if established could help in planning the extent of intervention needed in a given population. Data on sanitation and hygiene as well as altitude, which were collected as part of GTMP, were assessed to determine if they contributed to relationship between TF and TT. Results: The study included a total of 282,558 individuals living in 174 evaluation units from seven regions of Ethiopia, among whom 256,587 gave consent to be examined. This study found a significant relationship between the prevalence of TF in children and the prevalence of TT in adults when analysis is done at the evaluation unit level (correlation rho, 0.59; p-value <0.0001). Hence, 59% of the prevalence of TT in adults can be explained for by the presence of TF in children. Sub-group analysis showed that the correlation persisted at the regional level. Conclusion: A better understanding of the relationship between the prevalence of TF and the prevalence of TT together with the factors influencing this association using this large dataset may aid in prioritization of districts for intervention and has implications for global activities for the elimination of trachoma.

Part A of the dissertation includes the protocol of the study, which was approved by Faculty of Health Sciences Human Research Ethics Committee, University of Cape Town. The study was observational analytical, aiming to determine the magnitude and determinants of the ratio between prevalence of low vision and prevalence of blindness using Rapid Assessment of Avoidable Blindness (RAAB) surveys across World Bank regions. The surveys included in the study were available in the RAAB repository and obtained through permission from the primary investigators. A univariate and multivariate analysis were performed using the ratio as an outcome variable and potential explanatory variables as follows: prevalence of Uncorrected Refractive Error (URE), Cataract Surgical Coverage (CSC) at visual acuity 3/60, 6/60 and 6/18 for persons, logarithm of Gross Domestic Product per capita income and health expenditure per capita income. Part B contains the structured literature review. PubMed, Scopus, EBSCOHOST (Africa wide and MEDLINE) and Web of science databases were used to look for literature using the following key words: rapid assessment, blindness, age-related cataract, uncorrected refractive errors, low vision, visual impairment, avoidable OR curable OR preventable OR treatable. The summary of the literature review in addition to the gap in the literature is presented in the section. Part C includes a journal "ready" manuscript. The results showed that the ratio was between 1.35% in Mozambique and 11.03% in India. There was a statistically significant variation of the ratio across the regions: approximately 7.0 in South Asia and approximately 3.0 in Sub-Saharan Africa (X2=28.23, P<0.001). The variables: prevalence of Uncorrected Refractive Errors (URE), Cataract Surgical Coverage at visual acuity 3/60, 6/60 and 6/18 for persons, logarithm of Gross Domestic Product per capita and logarithm of health expenditure per capita were found to be statistically significantly associated with the ratio. However, only prevalence of URE and CSC at 3/60 for persons across the regions were found statistically significant in multivariate analysis.