Ultraviolet C (UV-C) Light Therapy Inhibits Pathogens Associated With Equine Keratomycosis at Different Corneal...

To assess if an inexpensive, commercially available ultraviolet C (UV-C) light device with a peak emission of 275 nm can inhibit equine keratomycosis-associated pathogens located at different corneal depths in an ex vivo model.

A controlled, randomized experimental design. Aspergillus fumigatus and Fusarium solani isolates were inoculated in fresh bovine corneoscleral transplants, superficially or at 450 μm of stromal depth for the ulcerative keratomycosis or stromal abscess model, respectively. After a minimum of 18 h of incubation, treatment groups received 15 s of UV-C light exposure at a 10 mm distance from the corneal surface level (22.5 mJ/cm² dose). Fungal inactivation was quantified by determining the mean fluorescent intensity (MFI) of two fungal viability markers (SYTO 9 = green = alive; PI = red = dead) utilizing confocal laser scanning microscopy.

UV-C treatment resulted in statistically significantly higher MFI-PI, lower MFI-SYTO 9 and lower normalized MFI ratios (SYTO 9/[SYTO 9 + PI]) compared to controls for both isolates irrespective of corneal depth; therefore demonstrating successful fungal inactivation. In superficial location, fungal inhibition reached 88% for both isolates. At deeper corneal depth, fungal inhibition was not significantly different for F. solani (84%) but significantly less complete for A. fumigatus (60%).

Corneal UV-C light treatment may offer therapeutic benefits for ulcerative keratomycosis and stromal abscesses in the equine species using doses expected to be safe for corneal exposure based on previously published safety data. Species-specific safety studies are required to ensure that antifungal efficacy aligns with safe clinical practice.