  The dilation of the pupil and it's variation between a mated pair of irides
has been found to be an important factor in the performance of iris recognition
systems. Studies on adult irides indicated significant impact of dilation on
iris recognition performance at different ages. However, the results of adults
may not necessarily translate to children. This study analyzes dilation as a
factor of age and over time in children, from data collected from same 209
subjects in the age group of four to 11 years at enrollment, longitudinally
over three years spaced by six months. The performance of iris recognition is
also analyzed in presence of dilation variation.
