Acute sixth nerve palsy in vitamin A treatment of xerophthalmia

Acute vitamin A toxicity generally occurs in children when a single dose greater than 330 000 IU is ingested, although some infants can be adversely affected by single doses as low as 100 000 IU. 3 4 Typical features include a bulging fontanelle in infants, raised cerebrospinal fluid (CSF) pressure, nausea and vomiting, vertigo, and blurred vision or diplopia. The sixth nerve palsy occurred presumably from raised CSF pressure, a phenomenon that is not fully understood but may be due to altered CSF resorption or production. 5 6 Acute toxicity from intramuscular vitamin A (particularly water miscible forms) may be more likely because of the higher serum levels that are achieved more rapidly compared with oral preparations. 7 Nevertheless, this case attests to the relative safety of vitamin A administration in infants.