Effect of therapeutic UVC on corneal DNA: Safety assessment for potential keratitis treatment

Antimicrobial ultraviolet C (UVC) has proven efficacy in vitro against keratitis isolates and has potential to treat corneal infection if safety can be confirmed. Safety of 265 nm, 1.93 mW/cm2 intensity UVC (15–300 s exposures) was investigated in vitro via cyclobutane pyrimidine dimer (CPD) formation in DNA of human cultured corneal epithelial cells; ex vivo, by evaluating UVC transmissibility as a function of porcine corneal thickness; and in vivo, by evaluating CPD induction in the mouse cornea following UVC exposure. A single exposure of 15 s UVC did not induce significant CPD formation (0.92 ± 1.45%) in vitro relative to untreated control (p = 0.93) whereas 300 s exposure caused extensive CPD formation (86.8 ± 13.73%; p