Seeing is believing: Objectively evaluating the impact of facial reanimation surgery on social perception

Objectives/Hypothesis Objectively measure the ability of facial reanimation surgery to normalize the appearance of facial paralysis using eye-tracking technology. Study Design Prospective randomized controlled experiment. Methods An eye-tracker system was used to record the eye-movement patterns, called scanpaths, of 86 naïve observers gazing at pictures of paralyzed faces (House-Brackmann IV-VI), smiling and in repose; before and after facial reanimation surgery; as well as normal, nonparalyzed faces. Observers gazed at each face for 10 seconds. Fixation durations for all predefined facial areas of interest were analyzed using mixed-effects linear regression. Results Observers spent the majority of time (6.6 of 10 seconds) gazing in the central triangle region (eyes, nose, and mouth) of normal faces and paralyzed faces. There were significant deviations in fixation within the central triangle of paralyzed faces as compared to normal faces. Total fixation on the eyes remained conserved. However, total nose fixation decreased and mouth fixation increased on paralyzed faces. Facial reanimation surgery normalized many of the hemifacial gaze asymmetries caused by unilateral facial paralysis, and restored a normal distribution of gaze between the functional and paralyzed sides of the face and mouth. Conclusion There were objective differences in the way observers directed their attention to facial features when viewing normal and paralyzed faces. After facial reanimation surgery, the attentional distraction caused by facial feature irregularities was reduced. These findings are important additions to the emerging body of objective evidence indicating the effectiveness of reanimation surgery; they also suggest opportunities to optimize reconstruction.