Apical pleural thickening is the thickening of pleura (2 very thin layers) covering the apical (top) portion of the lungs. There are many causes of this like infection or any other inflammatory disease process. Commonest cause in the developing countries is Tuberculosis-past or present. First you should get yourself thoroughly investigated to find out the cause and to estimate the functional impairment it is causing. If there is no active disease and there is no functional impairment, you may not have to do much and you will be cleared for visa. Treatment is by thoracoscopy
to remove the thickened pleura or by lobectomy
if underlying lung is also thickened(fibrosed).