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Ultraviolet C (UV-C) Light Therapy for Equine Ulcerative Keratomycosis-An In Vitro Study.
Abstract: To assess if an affordable, commercially available 275 nm ultraviolet C (UV-C) device can inhibit fungal pathogens associated with equine keratomycosis and to establish the optimal exposure time/dose required in vitro. Methods: Fungal inhibition zone surface areas of isolates from two fungal genera (Aspergillus and Fusarium spp.) were compared in triplicates after UV-C exposure at distances of 10, 15, and 20 mm with single or repeat doses (4 h apart) of 5, 10, 15, or 30 s duration after 24, 48, and 72 h of incubation. Inhibition zones were microscopically assessed, and regrowth checks were performed. Results: Fungal inhibition was achieved with the lowest exposures/doses of 5 s/7.5 mJ/cm and 10 s/7 mJ/cm at distances of 10 and 20 mm, respectively. At 10 mm, the fungal inhibition zone was statistically significantly enlarged by increasing exposure/dose from 5 s to 15 s/22.5 mJ/cm for all isolates. Only Aspergillus flavus showed a further significant zone enlargement after a 30 s/45 mJ/cm exposure/dose. Fungal inhibition zone sizes did not differ significantly between isolates after 15 s exposure regardless of distance, but an increased distance led to a subjective increase in fungal regrowth. While inhibition zones decreased over time, no central growth was noted despite the lack of complete fungal eradication. Conclusions: For Aspergillus and Fusarium spp., an exposure/dose of 15 s at a 10 mm distance/22.5 mJ/cm may optimally align antifungal efficacy with previously reported corneal safety data. Further preclinical and safety studies are required to ensure that this effect translates into clinical practice.
© 2025 The Author(s). Veterinary Ophthalmology published by Wiley Periodicals LLC on behalf of American College of Veterinary Ophthalmologists.
Publication Date: 2025-03-05 PubMed ID: 40045512DOI: 10.1111/vop.70012Google Scholar: Lookup The Equine Research Bank provides access to a large database of publicly available scientific literature. Inclusion in the Research Bank does not imply endorsement of study methods or findings by Mad Barn.
- Journal Article
Summary
This research summary has been generated with artificial intelligence and may contain errors and omissions. Refer to the original study to confirm details provided. Submit correction.
Overview
- This study investigated whether a commercially available ultraviolet C (UV-C) light device can effectively inhibit fungi that cause eye infections (keratomycosis) in horses.
- The research aimed to identify the optimal UV-C exposure time and dose that inhibits fungal growth in laboratory conditions.
Background and Objective
- Equine ulcerative keratomycosis is a fungal infection of the cornea in horses, primarily caused by Aspergillus and Fusarium species.
- Current treatments can be expensive or have limited efficacy, so alternative therapies are sought.
- UV-C light at 275 nm has known antimicrobial properties and could be a cost-effective treatment option.
- The study sought to test a commercially available UV-C device for its ability to inhibit fungal pathogens linked to this equine eye disease.
- The specific goals were to determine which exposure times and doses produce effective fungal inhibition in vitro and to assess safety based on existing corneal data.
Methods
- Fungal isolates from two genera linked to equine keratomycosis—Aspergillus and Fusarium—were grown in petri dishes.
- UV-C light at 275 nm was applied at different distances from the fungal cultures: 10 mm, 15 mm, and 20 mm.
- Exposure durations tested included 5, 10, 15, and 30 seconds.
- Doses were given either as a single exposure or repeated exposures 4 hours apart.
- The areas of fungal growth inhibition, called inhibition zones, were measured after 24, 48, and 72 hours of incubation.
- Microscopic examination was used to confirm the inhibition zones and to monitor fungal regrowth over time.
Key Findings
- Effective fungal inhibition was observed with short UV-C exposures:
- 5 seconds (7.5 mJ/cm²) at 10 mm distance
- 10 seconds (7 mJ/cm²) at 20 mm distance
- Increasing exposure time from 5 seconds to 15 seconds at 10 mm distance significantly increased the inhibition zone size for all fungal isolates.
- Only Aspergillus flavus showed further significant growth inhibition with a 30-second exposure.
- After 15 seconds of exposure, the inhibition zone sizes were similar across all isolates and distances tested.
- Greater distance between the UV-C source and fungi tended to allow more fungal regrowth, suggesting less effective treatment.
- Although inhibition zones shrank over time, no fungal regrowth was observed in the center of the inhibited area, implying persistent fungal suppression even without complete eradication.
Conclusions and Implications
- An exposure/dose of 15 seconds at 10 mm distance (delivering about 22.5 mJ/cm²) appears to provide the best balance between antifungal effectiveness and previously reported corneal safety limits.
- This finding supports the potential use of affordable, commercially available UV-C devices as adjunct treatment for fungal keratitis in horses.
- However, the study was conducted in vitro, so in vivo preclinical and safety studies are necessary to confirm that these doses are both effective and safe in live animals.
- Future research should also explore clinical protocols, possible tissue effects, and long-term outcomes before recommending UV-C as a standard therapy.
Cite This Article
APA
Hoerdemann M, Sahoo DK, Allbaugh RA, Kubai MA.
(2025).
Ultraviolet C (UV-C) Light Therapy for Equine Ulcerative Keratomycosis-An In Vitro Study.
Vet Ophthalmol, 29(1), e70012.
https://doi.org/10.1111/vop.70012 Publication
Researcher Affiliations
- Department of Veterinary Clinical Sciences, College of Veterinary Medicine, Iowa State University, Ames, Iowa, USA.
- Department of Veterinary Clinical Sciences, College of Veterinary Medicine, Iowa State University, Ames, Iowa, USA.
- Department of Veterinary Clinical Sciences, College of Veterinary Medicine, Iowa State University, Ames, Iowa, USA.
- Department of Veterinary Clinical Sciences, College of Veterinary Medicine, Iowa State University, Ames, Iowa, USA.
MeSH Terms
- Animals
- Horses
- Horse Diseases / radiotherapy
- Horse Diseases / microbiology
- Fusarium / radiation effects
- Corneal Ulcer / veterinary
- Corneal Ulcer / radiotherapy
- Corneal Ulcer / microbiology
- Eye Infections, Fungal / veterinary
- Eye Infections, Fungal / radiotherapy
- Eye Infections, Fungal / microbiology
- Ultraviolet Therapy / veterinary
- Aspergillus / radiation effects
- Ultraviolet Rays
Grant Funding
- KC Award 028567-00001 / International Equine Ophthalmology Consortium Research Grant
- CVM PG105121 / Iowa State University College of Veterinary Medicine Seed Grant
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