How does methanol toxicity affect vision?

Updated: Nov 05, 2018
  • Author: Kalyani Korabathina, MD; Chief Editor: Tarakad S Ramachandran, MBBS, MBA, MPH, FAAN, FACP, FAHA, FRCP, FRCPC, FRS, LRCP, MRCP, MRCS  more...
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Answer

The mechanism by which the methanol causes toxicity to the visual system is not well understood. Formic acid, the toxic metabolite of methanol, is responsible for ocular toxicity in animal models and is rightly presumed to be responsible in human studies. (See Etiology and Pathophysiology.)

Serum methanol levels of greater than 20 mg/dL correlate with ocular injury. Funduscopic changes are notable within only a few hours after methanol ingestion and range from retinal edema in the perimacular region to the entire fundus. Optic disc edema and hyperemia are observed within 48 hours.

Visual injury may be prevented with prompt antidote therapy or via elimination of the metabolites from the system with hemodialysis; however, this is not always the case. (See Treatment and Medication.)


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