Microbial keratitis in the age of resistance: unlocking the therapeutic potential of phage therapy

Keratitis an inflammatory disorder of the corneal tissue, poses a significant threat to vision and, if left untreated, can even progress to irreversible blindness. Clinical manifestations of the disease include ocular redness, pain, photophobia, excessive tearing, and visual disturbances, with severe cases often leading to corneal ulceration, scarring, or perforation. The global prevalence of keratitis exhibits substantial geographical variability, largely influenced by access to healthcare, environmental factors, and behavioral risk determinants, most notably, the use of contact lenses. In recent years, microbial keratitis (MK) has shown a concerning rise in incidence, particularly among contact lens users, frequently attributed to improper lens hygiene and extended wear. Current therapy mainly depends on the intensive use of topical antimicrobial agents; however, the emergence of multidrug-resistant (MDR) pathogens and the protective nature of biofilms significantly compromise therapeutic efficacy and efficiency. These limitations pave the way to the urgent need for alternative strategies. Bacteriophage therapy, which was in use even before the development of antibiotics, regained interest as a precision-based antibacterial treatment that is capable of selectively targeting pathogenic bacteria, including MDR strains, without disrupting the native ocular microbiota or damaging host tissue. This review explores the different types of keratitis and pathogenesis, highlights the problems related to conventional therapies, and emphasizes the potential of phage therapy as a novel, adjunctive, or standalone intervention.