Respuesta de la función de sensibilidad al contraste por medio de un test informatizado en población africana, Nampula, Mozambique

The quality of the visual system can be determined by means of different methods, the best known being the determination of Visual Acuity and Contrast Sensitivity Function (FSC), which provide information on the visual system and serve as indicators in the presence of any vision abnormality. However, from a clinical point of view, the use of FSC is much more interesting, due to the information it generates that can be crucial for the early care of ocular and visual pathologies. The Contrast Sensitivity Function is defined from the values ​​of the minimum noticeable contrast threshold for a given frequency. The representation of the inverse of these values ​​as a function of the spatial frequency allows us to construct the FSC. The objective of this thesis is the evaluation of the response of the contrast sensitivity function by means of a computerized test in the African population, during the years 2016 to 2018. For this, a derived FSC measurement test has been developed and validated of the Pelli-Robson test, which can be easily passed in a difficult clinical circumstance such as that existing in the province of Nampula (Mozambique). The test was passed to a total of 319 men and 426 women, and a statistical analysis was developed to develop a database of contrast sensitivity in an African population. The results were classified according to the most common pathologies in the area: refractive defects, presbyopia, cataract, IOL, HIV and tuberculosis.The results obtained with healthy patients establish a validation range that is compatible with those obtained in the different commercial tests. The results obtained in patients with refractive errors show the typical drop in high spatial frequencies found in other studies. The results obtained in patients with tuberculosis show a loss in medium frequencies that has already been referenced in other studies due to the retinal toxic effect of the medication, especially due to ethambutol-induced optic neuritis. In the case of cataract, IOL and presbyopia, the results are compatible with the previous bibliography. In the case of HIV, a reduction in mean frequencies is found due to the neuroretinal aggressiveness of the retroviral medication. As conclusions we can establish: • In Mozambique there are no published normative data on contrast sensitivity measurements for healthy patients, with refractive errors or with ocular disturbances. This is the first research carried out on this subject in the country. It is worth highlighting the collaboration of public entities such as the University of Lurio and hospitals, together with healthcare centers to obtain an investigation of these characteristics in a country with many difficulties such as Mozambique. • The FSC test is essential for the early diagnosis and follow-up of ocular pathologies or conditions. • From this study, the aim was to find a response that would serve as a normal response pattern for FSC in African patients. • The aim of this new test is to implement the FSC intake in clinical optometry consultations in the practical classes of the Optometry course of the Faculty of Health Sciences of the University of Lurio.