[Operational applications of the simplified coding system for trachoma and its complications].

In 1987, World Health Organization (W.H.O.) program for the Blindness Prevention proposed a simple system for coding and recording the various stages of Trachoma and its complications. Since this time, this system revealed to be a convenient and useful tool and was used in each epidemiological survey carried out together with Member States, either for blindness prevalence and causes studies as in Benin, Congo, Togo and Turkey, or for specific studies on Trachoma as in Vietnam, Morocco, Mali and in Kiribati. After a short presentation of the most significative results of these studies, the authors discuss on: 1--Details of practical use for this system in the field conditions, underlining particularly: training for future users; setting up of a study concerning reliability: this study has to be both easy an serious to allow an acceptable similarity between the observations of several examiners; some important points to calculate the size of the sample which has to be studied. 2--Main parameters and epidemiological signs which can be took on and invigilated thanks to this system.