A new clinical study has shown that a single five-second application of therapeutic ultraviolet-C (UV-C) light can substantially reduce bacterial load in the eyes of dogs, horses and cats with microbial keratitis (MK).

Published in Veterinary Ophthalmology, the retrospective study by Chris Dixon and Gary Lewin evaluated the immediate effect of low-dose 265nm UV-C irradiation on naturally occurring cases of microbial keratitis presented to a UK veterinary referral ophthalmology hospital.

The study analysed 34 affected eyes from 30 client-owned patients, including dogs, horses and cats. Corneal swabs were collected immediately before and immediately after a single five-second UV-C treatment using a commercially available therapeutic device. Bacterial cultures were then compared to assess the immediate microbiological effect.

Median bacterial counts fell by 96.5% while nearly one-third of treated eyes were culture-negative immediately after UV-C exposure. More than 94% of eyes achieved at least a 75% reduction in bacterial load, with reductions observed across a range of pathogens including Staphylococcus, Streptococcus, Pseudomonas and coliform bacteria.

Commenting on the findings, the authors note that demonstrating a significant immediate reduction in bacterial burden in naturally occurring clinical cases represents an important step in assessing the potential clinical application of therapeutic UV-C in veterinary ophthalmology.

The full paper, Immediate Reduction in Corneal Bacterial Load Following Therapeutic Ultraviolet-C Irradiation in Veterinary Patients with Microbial Keratitis, is published in Veterinary Ophthalmology: https://onlinelibrary.wiley.com/doi/10.1111/vop.70230