Little is really understood about glaucoma's mechanisms, mostly because they are constantly changing. For instance, one manageable symptom that seems to be linked to the disease's progression is high intraocular pressure, or pressure caused by too much liquid inside the eye. But intraocular pressure changes throughout the day, usually peaking at night when patients are not under doctor's observation. Snapshots of the condition taken during routine doctor visits provide little insight into how the symptoms and diseases are evolving.