Ocular quinine toxicity followed by electroretinogram, electro-oculogram, and pattern visually evoked potential

A patient who had ingested quinine as a suicide gesture was followed from 14.5 hr to 6 months with electrodiagnostic tests. The electroretinogram revealed early increased a-wave and decreased b-wave amplitudes, increased implicit times, and diminished oscillatory potentials. The electro-oculogram showed a decreased "light rise," and the pattern visually evoked potential was found to have an increased implicit time throughout the period of testing. These data indicate that there is an early direct toxic effect of quinine on the retinal cells.