Ingestion of methanol can result in ocular toxicity with blindiness.
Mechanism: generation of formaldehyde and formic acid
Susceptible cells: photoreceptors, Muller cells, optic nerve
Visual effects are often transient but can be permanent. The degree of metabolic acidosis at presentation determines the final visual acuity (Desai et al).
(1) blurred vision
(2) visual field loss
(3) visual hallucinations
Findings on exam:
(1) abnormal pupillary reactions
(2) hyperemic and edematous optical discs
(3) retinal edema
(4) cystoid macular edema
(5) "pseudo" cherry red spots
(6) paracentral scotoma
(7) enlargement of the blind spot
(8) optic neuropathy
Electroretinogram and visual-evoked response can document the severity of the poisoning.
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