This study deals with the avoidance/mitigation possibility in severity estimation of harm from a mechanical hazard when a sharp-edged object approaches to a human eye part. We assume that a sharp end effector of a robot approaches the eye of a human in a human-robot coexistence system. We conduct a static eye part collision experiment and dynamic eye part collision experiment taking human avoidance/mitigation actions into consideration. Three conditions, open/close eyelid, collision positions, and collision angles, are changed in the static collision experiment. Consequently, it is confirmed that differences in severity come out from the changes in the experimental conditions. In the dynamic collision experiment, Bell's phenomenon, which is an upward rotation of the eyeball at the time of closing the eyelid, is taken into consideration and two conditions, collision positions and angles, are changed. Through the experiments, we find that Bell's phenomenon plays an important role for risk estimation. Although the avoidance/mitigation possibility has not been taken into consideration in eye part collision experiments, we consider that it is indispensable to risk estimation.