Photophobia is a medical condition involving extreme sensitivity to light, whether artifical or from the sun. The assumption made by the young man that the lady is suffering from it demonstrates how he is a product of modern Europe; during the 18th Century vampire hysteria it had been believed that aversion to light was evidence of vampirism. Photophobia generally presents itself as a symptom of an underlying condition. If there is injury or infection in some part of the eye, its ability to process light is much weakened and causes photoreceptors in the retina to put strain on the optic nerve. Problems such as cataracts, corneal abrasions and conjunctivitis can all cause this, as can temporary illnesses such as influenza, or migranes. It can be part of a group of problems if a serious illness is being fought, or may simply be a sign of extreme tiredness. Treatment therefore depends on various factors, but sufferers are normally advised to rest in a dark room, or wear sunglasses.