Which of the following is the characteristic ocular manifestation of methanol poisoning?

Explanation

## Ocular Manifestations of Methanol Poisoning **Key Point:** Formic acid (the toxic metabolite of methanol) causes selective damage to the optic nerve, resulting in optic neuritis and permanent optic atrophy if untreated. ### Mechanism of Optic Nerve Damage 1. Formic acid accumulates in the optic nerve and retina 2. Causes demyelination and axonal degeneration 3. Results in optic neuritis (acute inflammation) 4. Progresses to optic atrophy (permanent nerve damage) if not treated early ### Clinical Presentation of Methanol Poisoning | Feature | Details | |---------|----------| | **Acute phase (6–24 hrs)** | Headache, dizziness, nausea, abdominal pain, visual blurring | | **Optic phase (12–48 hrs)** | Optic neuritis, photophobia, scotomas, vision loss | | **Late phase** | Optic atrophy, permanent blindness if untreated | | **CNS effects** | Metabolic acidosis, seizures, coma | **High-Yield:** The classic saying is "Methanol causes **blindness**, ethanol causes **drunkenness**." Optic nerve damage is pathognomonic for methanol toxicity. **Clinical Pearl:** Fundoscopy in acute methanol poisoning may show optic disc hyperemia and edema. Later, optic atrophy appears as pallor of the disc. **Mnemonic:** **FOAM** — Formic acid → Optic neuritis → Atrophy → Methanol