With the increasing proportion of senior citizens, many mobility aid devices were developed such as the rollator. However among walker’s users, 87% of their falls is attributed to rollators. The EyeWalker project aims at developing a small device for rollators to protect elderly people from such dangers. Descending stairs are ones of the potential hazards rollator users have to daily face. We propose a method to detect them in real-time using a passive stereo camera. To meet the requirements of low-power consumption, we examined the performance of our stereo vision based detector with regard to the camera resolution. It succeeds in differentiating dangerously approaching stairs from safe situations at low resolutions. In the future, our detector will be ported on an embedded platform equipped with a pair of low-resolution and high dynamic range stereo camera for both indoor and outdoor usage with a battery-life of several days.