(Image from Tangled)
Disney's animation studios stay on the technological cutting edge with the assistance of company-operated research laboratories. One team of Disney researchers developed a means to capture the individual shape of human eyes in rich detail, including the deformation that the eyes experience as the pupils dilate.
(Image of 9 human irises by Disney Research)
The research, which you can see summarized in the video below, has led to the development of precise eye deformation simulation programs. Animators can use these to automatically generate pupil dilation that results from changing light conditions in cartoon settings.
-via Marginal Revolution