Before revision: The visual field is "that portion of space in which objects are visible at the same moment during steady fixation of the gaze in one direction"; in modern ophthalmology and neurology it is considered “the field of functional capacity obtained and recorded by means of perimetry”.A related definition is “The visual field refers to the area visible during stable fixation of the eyes, specified in degrees of visual angle.”Strasburger, Hans; Pöppel, Ernst (2002).
After revision: The visual field is "that portion of space in which objects are visible at the same moment during steady fixation of the gaze in one direction"; in modern ophthalmology and neurology the emphasis is on the structure inside the visual field and it is then considered “the field of functional capacity obtained and recorded by means of perimetry”.A related definition is “The visual field refers to the area visible during stable fixation of the eyes, specified in degrees of visual angle.”Strasburger, Hans; Pöppel, Ernst (2002).