Central diabetes insipidus (CDI) is a hypothalamus-pituitary disease characterized by polyuria and polydipsia due to a vasopressin (AVP) deficiency. It can be inherited or acquired (hereditary CDI and acquired CDI; see these terms).

Blepharochalasis is characterized by recurrent, non-painful, nonerythematous episodes of eyelid edema. It has been divided into hypertrophic and atrophic forms. In the hypertrophic form recurrent edema results in orbital fat herniation through a weakened orbital septum. Most patients who have blepharochalasis present in an atrophic condition with atrophy of redundant eyelid skin and superior nasal fat pads.