Abstract
Purpose :
Far-ultraviolet C (UVC) is an efficient germicidal tool. Despite this, the safety issue of far-UVC exposure has been a point of contention on the ocular surface, preventing their large-scale implementation in the clinic. Thus, the purpose of this study is to investigate the safety and disinfection ability of 222nm far-UVC exposure on rat corneal tissue. To evaluate the effectiveness of far-UVC exposure in disinfecting surgical wounds, its efficiency was compared to that of traditional disinfectants, such as 5% povidone-iodine (PVP-I, known as Betadine) (diluted in balanced salt solution).
Methods :
To evaluate the safety of 222-nm far-UVC exposure, rat corneas were exposed to 222-nm far-UVC at fixed intensity (3 mW/cm2) and distance (2 cm) for 1, 5, 10, 15, and 20 seconds. H&E stain, terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) assay, and reactive oxygen species (ROS) assay were used to assess the cornea’s tissue damage, apoptosis, and inflammatory response, separately. For disinfection, the rat received 222-nm far-UVC treatment in a safe exposure window to destroy germs on the corneal surface. The viable bacteria on the corneal surface were collected by using contact plate stamping and analyzed with colony count and identification (gram stain, colony morphology, coagulase agglutination). Colony counts were measured by the number of colonies formed per plate.
Results :
The 222-nm far-UVC radiation didn’t trigger apoptosis and inflammatory response within 1 to 5 seconds (below 15 mJ/cm2) of exposure in rat corneal tissue. Some apoptotic cells were detected in the first layer of corneal epithelium after 10 seconds (more than 30 mJ/cm2) of 222-nm far-UVC exposure. In comparison to 5% PVP-I, the number of all bacteria strains is significantly lower after 3 seconds (9 mJ/cm2) of exposure. Among all the bacteria strains, the reduction of 90.5% is the most significant after exposure to 222-nm far-UVC.
Conclusions :
Our data demonstrated that 9 mJ/cm2 of 222-nm far-UVC exposure is not only safe for corneal epithelial cells but also sufficient to eliminate bacteria on the corneal surface. Ultimately, this study provides critical information to develop a safe, efficient, and non-irritating disinfection method for ophthalmologic surgeries.
This abstract was presented at the 2023 ARVO Annual Meeting, held in New Orleans, LA, April 23-27, 2023.