Microbial keratitis is a vision threatening infection of the cornea. It may be caused by bacterial, fungal or viral infection. Contact lens wear is a major factor that increases the risk of bacterial or fungal keratitis and millions of users around the world are at risk. As with all infections causative organisms now commonly show resistance to traditional antimicrobial agents limiting the treatment options. Antimicrobial peptides are small peptides with potent activity against bacteria, fungi and some viruses and are recognized to have a low risk for selecting for resistant organisms. Here we propose the use of a specific peptide called Esculentin la and derivatives thereof for the treatment and prevention of microbial keratitis. This may be as a topical formulation of peptide in solution or tethered to a particle or in the guise of an "antimicrobial contact lens" in which peptide is covalently tethered to the surface of the lens.