[Severe bilateral keratomalacia]

In contrast to developing countries, xerophthalmia is rather rare in developed countries. Malnutrition (e.g. in mentally deficient or psychiatric patients), chronic liver diseases (e.g. due to alcoholism), or bowel surgery can be reasons for vitamin A deficiency in developed countries. The prodromal stage of hypovitaminosis A is characterized by nyctalopia, which often manifests subclinically. Longer lasting and severe cases of vitamin A deficiency may be complicated by the occurrence of keratinizing metaplasia in the cornea and conjunctiva, xerosis, keratomalacia or blindness.