Otto Lowenstein, a pioneer in the study of pupil function, began his professional life as an academic neuropsychiatrist at the University of Bonn with an interest in experimental psychology. From his teacher Alexander Westphal, he developed a fascination with the pupil. He invented ingenious recording devices and took motion pictures of the pupils, graphing their movements. Forced to flee Nazi persecution in 1933, he took temporary refuge in Switzerland and eventually sacrificed a flourishing career in Europe to escape to New York. During the next 25 years, he collaborated with Irene Loewenfeld on experiments and publications related to the clinical use of pupillary signs and introduced pupillography to American neuro-ophthalmology.