[A differential diagnostic test for optic neuritis].

A temporary lowering of body temperature by means of cold drinks, tried on a group of 18 patients with acute optic neuritis, led in 14 cases to a significant improvement in the 30 degree visual field, which the authors tested with the Octopus 201 automatic perimeter. In a group of 11 patients (17 eyes) who had previously had optic neuritis an improvement in the visual field was only seen in 8 eyes; in the other 9 eyes there was a deterioration. A slight deterioration in the 30 degree visual field after lowering body temperature was demonstrated in a group of 7 patients (12 eyes) with various diseases of the optic nerve as well as in 5 other healthy subjects. The temporary improvement in the patients with acute optic neuritis was probably caused by a reversible increase in the conductivity of the demyelinated nerve fibers as a result of lowering body temperature.