Hypopyon is a medical condition involving inflammatory cells in the anterior chamber of the eye.

It is an exudate rich in white blood cells, seen in the anterior chamber, usually accompanied by redness of the conjunctiva and the underlying episclera.

[1] Hypopyon is also known as sterile pus because it occurs due to the release of toxins and not by the actual invasion of pathogens.

The toxins secreted by the pathogens mediate the outpouring of leukocytes that settle in the anterior chamber of the eye.

This is in contrast to hypopyon resulting from toxins where the leukocytes settle at the bottom of the anterior chamber.