There are many reasons for dry eyes which may be caused by insufficient tear secretion, for example, tear secretion gradually decreases with age, and most elderly people will have dry eyes. If there is a systemic immune disease, such as dry syndrome, both eyes are dry and sore with obvious symptoms and may also be accompanied by dry mouth and dry skin. It may also be caused by rapid evaporation of tears, for example, if young people stay up late, look at their cell phones or computers for long periods of time, resulting in reduced transient eye movements, or if lid gland dysfunction results in reduced secretion of the lipid component of tears, eventually leading to decreased tear film stability. After eye surgery the nerves on the surface of the eye may be affected, which can also lead to reduced blinking of the eyes showing signs of dry eye.