Tunnel vision is a form of vision defect where a patient loses some or most of their peripheral vision while maintaining the central portion of their vision. As such, a patient with tunnel vision will be able to read and navigate, but will be unable to see anything to their sides or to describe a scene. They may be able to see features of faces, but not be able to recognize a face. It can also have several different underlying causes from loss of cells of the retina to neurological problems to loss of control of the muscles of the eye.
Tunnel vision is a symptom of several disorders including glaucoma, blood loss, heavy alcohol consumption, illegal drugs, severe anxiety attack, hypoxia, oxygen toxicity, brain tumors, cataracts or even mercury poisoning.
Indications of tunnel vision are normal for people wearing eyeglasses, a protective mask, or goggles, whose peripheral vision is either blocked by the frame frame or is blurry at the edges.