The eye is composed of a fluid called intraocular fluid. This fluid is further divided into two portions that work to maintain the correct pressure of the eye also known as intraocular pressure. These two fluids are the aqueous humor and the vitreous humor.
When debris is present in the aqueous humor, or during bleeding into the eye, the area surrounding the aqueous humor has particles that engulf or eat this debris or infection causing substances. The debris is broken down to small particles that are not harmful to the eye and destroyed.
Note that this debris if not cleared away can lead to complications such as glaucoma.