Bilateral Optic Neuropathy Following Methanol Ingestion: A Review of Published Cases

Abstract

ackground: Methanol poisoning causes acidosis and bilateral visual failure through its metabolite formate rather than through
methanol itself, often after a latent interval when the patient appears well. Objective: To set out which published variables predict blindness and death, and which treatments the record supports. Methods: Narrative review of published outbreak cohorts, prospective and retrospective series and case reports. Findings: In 38 prospectively studied patients, serum formate discriminated outcome with an area under the curve of 0.64 against 0.54 for serum methanol. In an ophthalmic series of 21 patients, mean blood methanol was higher in those without ocular symptoms. Admission arterial pH below 7.3 carried a risk estimate of 11.65 for chronic retinal nerve fibre layer loss in 42 survivors. Conclusions: The published record supports decisions based on pH, base deficit and formate and early blockade of alcohol dehydrogenase; it does not support reassurance from a blood methanol concentration.