Though with a starting word of “black”, if watch them carefully, you will find that most of the black eyes are not really black. Generally speaking, black eyes can be divided into: the cyan one, and the dark brown one. The causes of these two kinds of black eyes are really different: the cyan ones are caused by long-term retention of the venous blood, and it usually can be seen among young people about 20 years old, while the dark brown ones are the consequence of the disorder of melanin.

The contents above are a brief introduction of the definition and causes of black eyes. In next article, I will give you some methods to cope with these unwelcomed guests, for example, erbium glass fractional laser.