A 222-nm UV light effectively kills most ocular pathogens in 20 seconds.
It’s a given that ultraviolet (UV) light is effective at killing organisms, noted J. James Rowsey, MD. Though a 365-nm wavelength lamp often has been used, Dr. Rowsey touted the greater strength of a 222-nm UV light source technology (Far-UV Sterilray).
“We know that 222 nm will kill just about everything at a very low dose, including methicillin-resistant Staphylococcus aureus [MRSA] and Clostridium difficile,” said Dr. Rowsey, St. Michael’s Eye and Laser Institute, Largo, FL.
“The safety margin is enormous. It takes only 1/100th of the dose that will hurt tissue to kill yeast, bacteria, and E. coli.” The 222-nm light kills most ocular pathogens in 20 seconds, making it more effective than the 365-nm ultraviolet (UV) light typically used with the corneal collagen crosslinking (CXL) regimen for keratoconus, he added.
Two years ago, Dr. Rowsey presented on the safety of the 222-nm Far-UV light on the corneal endothelium by specular microscopy. A colleague asked whether a TUNEL assay would be more auspicious.
“We did exactly that,” he said. “The 222 nm was toxic to microbes at 5 seconds, but even at an hour it was not toxic on the epithelial surface. If we photodisinfect from the outside of the cornea inward, we’re safe.”
J. James Rowsey, MD
This article was adapted from Dr. Rowsey’s presentation at the 2017 meeting of the American Academy of Ophthalmology. He did not indicate proprietary interest in the subject matter.