Clinical outcome of methanol metabolism: The oxidation of methanol in human retinal tissue indirectly leads to which consequence?

Introduction / Context:
Methanol ingestion can cause profound visual impairment. The toxicity stems from metabolites rather than methanol itself. Recognizing the specific clinical consequence clarifies why rapid antidotal therapy is essential.

Given Data / Assumptions:

• Methanol → formaldehyde → formic acid (formate).
• Formate inhibits mitochondrial cytochrome c oxidase, disrupting ATP production.
• Optic nerve and retinal cells are energy-dependent and vulnerable to mitochondrial inhibition.

Concept / Approach:
The critical lesion is optic neuropathy due to formate accumulation, leading to blurred vision, visual field defects, and potentially permanent blindness. While other ocular symptoms may occur, the hallmark severe outcome is vision loss, not necessarily elevated intraocular pressure or isolated color vision defects.

Step-by-Step Solution:
Trace metabolism to formate, the principal toxin.Formate inhibits oxidative phosphorylation → cellular hypoxia/energy failure in optic tissues.Clinical result: optic nerve damage → blindness.Therefore, choose blindness as the indirect consequence.

Verification / Alternative check:
Case reports show correlation of serum formate with visual toxicity; treatment with fomepizole/ethanol (ADH inhibition) and folinic acid (enhances formate oxidation) improves outcomes if early.

Why Other Options Are Wrong:

• Pressure build-up: Not the principal mechanism; glaucoma-like pressure changes are not typical of methanol toxicity.
• Color blindness only: Dyschromatopsia can occur but the primary feared outcome is severe, sometimes irreversible, blindness.
• All of these: Overstates findings; key endpoint is blindness.
• Transient myopia always resolves: Not a defining or reliable feature.

Common Pitfalls:
Assuming ethanol-like effects; methanol is uniquely dangerous due to its metabolites.

Final Answer:
Blindness (optic neuropathy) due to formate toxicity.