This usually refers to a drop or pill that is designed to kill or decrease the proliferation of bacteria. The eye is well protected from infection by the conjunctiva and the corneal epithelium. In addition, the tear film contains antimicrobials and the tear flow itself tends to wash away pathogens. The eye also harbors a host of non-pathogenic bacteria that competitively prohibit new bacteria growth. However, these eye defenses can be breached by trauma, improper tearing, or contact lens wear and lead to an infection. Topical antibiotics work best for the eye given the avascular nature of the cornea.