In NEUROLOGY, as well as in other branches of medicine, there is a tendency to classify function without stating the conditions under which it operates. Thus, when a patient is said to have a homonymous hemianopsia, a complete loss of all visual function in the anopic area is implied. This implication, however, is valid only for the conditions under which the examination is performed. A change in these conditions might lead to a different result, the apparent absence of function reflecting merely the particular set of conditions under which the function is examined.
In previous communications, it was demonstrated that perimetrically determined macula-splitting hemianopsias, when tested with the methods of tachistoscopy or visual after-imagery, may reveal preservation of vision in some of the defective areas.1 On the other hand, the presence of function does not always imply complete preservation. Examination of fields of vision with such special methods as
BENDER MB, KRIEGER HP. VISUAL FUNCTION IN PERIMETRICALLY BLIND FIELDS. AMA Arch NeurPsych. 1951;65(1):72-79. doi:10.1001/archneurpsyc.1951.02320010078009