Color Vision Test with’ standard Pseudo-Isochromatic Plates Part 2’ for Ethambutol-Induced Optic Neuropathy

Abstract

Sixteen cases of Ethambutol-induced optic neuropathy were followed up using ‘Standard Pseudo isochromatic Plates Part 2 for Acquired Color Vision Defect’ (SPP-2 for short).

Patients mildly affected showed mostly red-green defect while those severely affected had developed both red-green and blue-yellow defects resulting to be achromatopsia-like.

Extent of color vision defects revealed by SPP-2 paralleled well with visual acuity, that is, presumably with the course of optic neuropathy. One of the patients happened to be seen several days before the onset of optic neuropathy, and owing to that, the initial symptoms were able to be appreciated. In regard of this case, color vision disturbance detectable with SPP-2 was seen no earlier than lowering of visual acuity and central scotoma developed even later.