Two year electrophysiology follow-up in quinine amblyopia. A case report

A 19-year-old girl presenting with quinine amblyopia had serial electrophysiology studies over a 2 year period. Visually evoked responses and the electro-oculogram were abolished early. By 2 months the VER and visual acuity had returned to normal. The electroretinogram, initially mildly subnormal, became virtually abolished by 2 months. No recovery in cone function took place. Of the rods 50% regained function with normal latency by 1 year, but receptor sensitivity did not return to normal until 2 years after ingestion. The electro-oculogram also recovered slowly over a 2 year period. This pattern suggest that quinine exerts a direct toxic effect on the cells of the outer retina and pigment epithelium, as well as on the ganglion cells.