The use of human iris images is considered one of the safest ways to provide biometrical recognition. On iris images obtained with natural lighting, the presence of reflection in its surface difficult the process of segmentation and extraction of the patterns present in its texture. This present work has as objective studying and applying techniques for segmentation of the iris region on videos of human eyes obtained via natural lighting. To do this, methods focusing on improving the location of the internal and external iris contour were used in images obtained on these conditions. Some procedures were also made to the removal of present noise over the iris region, such as eyelids and reflections. The results showed that the search of the internal iris region via estimation of its shape provided high matching rates on the segmentation of this region on the video analysis.