Dark adaptation abnormalities and recovery in acute thioridazine toxicity.

PUPOSE: To document acute thioridazine toxicity from the symptoms only, through the development of ophthalmoscopic signs and recovery of dark adaptation and electroretinogram responses. These findings support the thesis that visual loss is metabolic and reversible if diagnosed early. METHODS: Case Report. RESULTS: A case is presented of acute thioridazine toxicity with documentation of the development of symptoms before any ophthalmoscopic evidence of toxicity. This case uniquely shows the time course of dark adaptation, showing both delay in adaptation and elevated final threshold, it includes full electrophysiologic studies from within the first weeks of symptoms and regular follow-up demonstrating marked recovery of dark adaptation in terms of both delay and final threshold, a nearly normal electroretinography and normal color vision within 10 months. CONCLUSION: Our findings give support to the thesis that functional visual disturbance is primarily metabolic and reversible if detected early in the course of toxicity.