Acute toxic blindness: unrecognized quinine poisoning.

Two cases of acute blindness due to quinine poisoning are presented. In both cases, the diagnosis was initially unsuspected. In addition, tinnitus, decreased hearing, vomiting, abdominal pain, and confusion were noted in one patient, and the other experienced decreased hearing, headache, confusion, tachycardia, later bradycardia, and first-degree atrioventricular block. The onset of blindness was delayed more than 12 hours after ingestion in both cases. Quinine levels of 13.6 micrograms/mL and 18.6 micrograms/mL were demonstrated (therapeutic = 1 to 3 micrograms/mL). One patient developed marked constriction of visual fields and some residual decreased acuity, while the other regained normal visual acuity.