Humayun is a clinician-researcher at the University of Southern California (USC) Eye Institute, and a professor of ophthalmology and biomedical engineering for the
Keck School of Medicine of USC and USC Viterbi School of Engineering. He holds the Cornelius J. Pings Chair in Biomedical Sciences. He was named Professor of Ophthalmology, Biomedical Engineering, Cell and Neurobiology in 2001. He served as Interim Chair, Department of Ophthalmology, in 2013. He was named Inaugural Director of the USC Eye Institute in 2013. He was named Director of the USC Sensory Science Institute in 2013. Humayun has served as a Visiting Associate in Medical Engineering at the
California Institute of Technology since 2014. He serves on the board of directors for the American Society of Retina Specialists, and the Board of Directors of Replenish, Inc. ==Research==