Loss of Peripheral Vision
Individuals with loss of vision on the periphery, so called tunnel vision, retain clear central vision. In some cases small patches of retinal activity on the periphery are preserved, making it possible to detect movement and objects that assist with one's orientation. Typically, an individual with loss of side vision will not automatically perceive the loss as the areas where there is no retinal cell activity are neither light nor dark. This can be compared in trying to perceive what takes place in a room behind our back.
An individual tries to orient himself. He looks at the train as it arrives and tries to locate the doors.
He shifts his focus to the train schedule to determine whether this is the correct train or not. Once returning his focus to the doors, they appear to have disappeared as they are blocked by passengers he didn't see coming.