Illustration of an eye with a corneal abscess with hypopyon. The cornea is the transparent front part of the eye. An abscess is usually caused by a bacterial infection, resulting in the formation of a pus-filled swelling. Hypopyon is a severe form of inflammation and formation of an exudate shown here filling the bottom of the anterior chamber of the eye. From New Dictionary of Practical Medicine and Surgery by Dr Jaccoud Vol. 18 (1874).