In vitro antimicrobial efficacy of riboflavin, ultraviolet-A radiation, and combined riboflavin/ultraviolet-A radiation on ocular pathogens

PURPOSE: There is a lack of studies evaluating the antimicrobial effect of riboflavin and ultraviolet-A (UVA) radiation using an epithelium-off cross-linking technique (Dresden protocol) in the literature. This study aimed to demonstrate the antimicrobial properties of riboflavin and UVA radiation and combined riboflavin/UVA radiation on various ocular pathogens Dresden protocol. MATERIALS AND METHODS: This was a prospective and comparative study. This study included four groups: Staphylococcus aureus, Pseudomonas aeruginosa, Candida albicans, and Acanthamoeba. All the groups were tested 12 different times with riboflavin alone, UVA light alone, and combined riboflavin with UVA. The growth inhibition zones were measured. Descriptive statistics were expressed as mean and standard deviation. The main outcome was measurement and analysis of growth inhibition zones. RESULTS: The mean growth inhibition zones following riboflavin and UVA exposure were 9.70 ± 1.63 mm for P. aeruginosa and 7.70 ± 1.08 mm for S. aureus. The mean growth inhibition zones for P. aeruginosa were greater than for S. aureus (t = 2.395, P = 0.038). The mean growth inhibition zones for C. albicans and Acanthamoeba were 0. The mean growth inhibition zones following UVA exposure alone and riboflavin alone for all organisms were also 0. CONCLUSION: Combined riboflavin and UVA in the clinical dose was effective against P. aeruginosa and S. aureus but ineffective against C. albicans and Acanthamoeba. Our study shows the potential of combined riboflavin and UVA in the treatment of bacterial keratitis.