The epithelium of the cornea is depicted with an overlying mucus layer. A hypothetical progressive sequence is presented in which successive antimicrobial defenses are recruited. The tear film proteins, lysozyme, lactoferrin, and lipocalin create an environment that is nonoptimal for microbial growth. The mucin layer, derived from mucins secreted by the epithelium, creates a physical barrier that microbes must overcome in order to invade the cornea. (i) Should a microbe penetrate the mucin layer, it faces constitutively expressed antimicrobial peptides, such as human β-defensin-1 (hBD-1). (ii) If the microbe gains access to the epithelium, we imagine that cytokeratin fragmentation, as described by Tam et al., generated by cleavage of a preexisting abundant protein, is rapidly mobilized. (iii) Expression of a battery of antimicrobial peptides is subsequently induced over the course of hours.