Increase in short-term fluctuation may be a clue for differentiating dystrophic from acquired defects in anterior visual pathways.

Abstract

To the Editor. —In clinical practice, dystrophic lesions of the anterior visual pathways may be misdiagnosed as acquired lesions, and vice versa.1In acquired defects, transient changes in visual function often occur,2whereas they rarely occur in dystrophic disorders of these neural pathways. OCTOPUS (Interzeag AG, Schlieren, Switzerland) automated perimeter programs offer two modes of evaluating transient changes in visual function, according to the program selected: (1) the so-called root mean square fluctuation, or (2) the short-term fluctuation (SF), both of which require a time interval of less than 15 minutes between threshold testings. However, there are indications that the SF index is the more accurate means of measuring these transient changes in visual function.3 We therefore analyzed SF values (computed by the G1 program) obtained (1) from 41 examinations evaluating defects in optic neuritis or anterior visual pathway compression, and compared these values with those obtained