The visual field is the portion of the subject's surroundings that can be seen at any one time. The normal extent of field of vision is 50° superiorly, 60° nasally, 70° inferiorly and 90° temporally. A visual field defect is a loss of part of the usual field of vision, so it does not include severe visual impairment of either one eye or both. The lesion may be anywhere along the optic pathway; retina to occipital cortex.
This is a companion discussion topic for the original article at https://patient.info/doctor/history-examination/visual-field-defects