Delayed recovery of vision after blindness caused by methanol poisoning

Total blindness developed in an adult Melanesian man 36 hours after he drank 100 mL of 100% methanol. On admission to hospital, he had a blood methanol level of 0.5 g/L and severe acidosis. Peritoneal dialysis was carried out, and he was treated with sodium bicarbonate and ethanol for one week. After 12 days of blindness, he regained some light perception. Progressive improvement in vision occurred. Twelve weeks after the methanol poisoning, his visual acuity was: right eye, able to see hand movements at one metre; left eye, 6/12. However, a right central scotoma persisted, and bilateral optic atrophy was present. No reason for the exceptional delay before recovery and degree of recovery could be deduced, although throughout his convalescence he frequently chewed betel nut. We recommend further studies to determine if any of the constituents of betel nut diminish the toxic effects of methanol on the eye.