[Accidental staining of corneal nerves by methylene blue].

A 10-year-old child presented after accidental exposure of the left eye to a blue hair dye containing methylene blue. Mild ocular surface changes and a selective blue staining of the usually invisible corneal nerve fibre bundles were present. Corneal sensitivity was reduced. Despite copious lubrication a transient neurotrophic keratitis developed which did not resolve until corneal sensitivity became normal 2 weeks later. Association of mild chemical burns with neurotrophic keratitis is unusual but is of high clinical relevance as keratitis is a vision-threatening complication.