Effect of ultraviolet-A-induced corneal collagen cross-linking in the management of Staphylococcus epidermidis keratitis: In vitro study

PURPOSE: Bacterial keratitis remains a significant cause of corneal morbidity and visual impairment. Increasing resistance to antimicrobial therapy has prompted interest in alternative or adjunctive treatments, including corneal collagen cross-linking (CXL) with ultraviolet-A (UV-A) and riboflavin. The aim of the study is to develop an in vitro human corneal infection model and to evaluate the efficacy of UV-A-induced corneal collagen CXL as an adjuvant treatment for Staphylococcus epidermidis keratitis. METHODS: Three human donor corneas were dissected into quadrants and assigned to four experimental groups: (1) control (noninoculated and nontreated), (2) inoculated only, (3) inoculated and postinfection cross-linked, and (4) precross-linked and subsequently inoculated. All infected samples were exposed to S. epidermidis and the CXL procedure was applied either 24 h prior to or 24 h following bacterial inoculation. Corneal tissues were processed and analyzed using hematoxylin and eosin staining and immunohistochemistry. RESULTS: The postinfection CXL group demonstrated a significant reduction in bacterial load compared to the inoculated-only and precross-linked groups. Moreover, there was limited bacterial spread, and posterior stromal architecture was better preserved in the treated corneas. CONCLUSION: The study successfully established a human in vitro model of bacterial keratitis. UV-A-induced corneal collagen CXL shows promise as an effective adjunctive therapy for S. epidermidis keratitis by mitigating bacterial invasion and preserving tissue integrity.