Evidence Library / Condition guides
Condition guide · Dogs and cats
Melting corneal ulcers: where UVC fits.
A guide for veterinary teams
24%
of melting ulcers in a UK referral study grew pure Pseudomonas aeruginosa (26 of 110)
13%
of eyes in the same study were lost to enucleation despite treatment (14 of 110)
57%
of those lost eyes had a pure Pseudomonas infection (8 of 14)
A melting ulcer can progress from a corneal defect to perforation within days. Controlling infection is central to saving the eye, and UVC offers an immediate, broad-spectrum way to cut the bacterial load while culture results are pending.
What it is.
Keratomalacia is a rapidly progressive corneal ulcer in which the stromal collagen breaks down. An imbalance between collagen-degrading enzymes and their natural inhibitors drives the melt, and secondary bacterial infection often makes it worse. Brachycephalic breeds are predisposed. Without prompt, aggressive treatment the ulcer can perforate, cost the patient its sight, or need enucleation.
Why it’s hard to treat.
- Pseudomonas aeruginosa and β-haemolytic Streptococcus are the most common culprits, and they respond to different antibiotics.
- In a UK referral study of 110 melting ulcers, 43% grew nothing on culture (47 ulcers), so the organism isn’t always confirmed.
- Culture and sensitivity results can take 48 to 72 hours, so first-line treatment is empirical.
- Pure Pseudomonas infections were significantly more likely to end in loss of the eye.
Where UVC fits.
UVC acts on microbial DNA directly, so it works whichever organism is present and whatever its antibiotic sensitivity. In a 2026 study of 34 infected eyes, a single 5-second PhotonUVC treatment cut bacterial load by a median 96.5%, with reductions seen in Pseudomonas, Streptococcus, Staphylococcus and coliforms. In laboratory and mouse studies, 265 nm UVC cleared Pseudomonas keratitis, including a multi-drug-resistant strain, and killed established Pseudomonas biofilm. UVC is an addition to intensive medical therapy and surgical support, not a replacement for them.
What the evidence doesn’t show yet.
- No study has yet reported healing time, globe retention or perforation rates for melting ulcers treated with UVC.
- The 2026 clinical study measured bacterial load immediately after one treatment, without a control group.
- UVC targets infection. It is not an anti-collagenase treatment, so protease control and surgical support remain essential.
- The safety studies used intact corneas; evidence in deep stromal ulcers and descemetoceles is limited.
Sources
- Veterinary Ophthalmology, 2021;24(3):265–278
- Melting corneal ulcers (keratomalacia) in dogs: a 5-year clinical and microbiological study (2014–2018)
- Journal of Microbiology, Biotechnology and Food Sciences, 2025;14(6):e12410
- Zubrický P, Balicka A, Trbolová A. Treatment options for melting ulcers in dogs and cats
About this guide
Written by Photon Therapeutics for veterinary professionals. It summarises published evidence and is not a substitute for clinical judgement. Photon Therapeutics makes the PhotonUVC Vet device.
The evidence.
Veterinary clinical study · 2026
Single 5-second UVC treatment cuts bacterial load in dogs, horses and cats
Median 96.5% drop in bacterial count across 34 eyes at a UK referral hospital.
Independent efficacy study · 2025
UVC against multi-drug-resistant Pseudomonas keratitis
Independent study: no bacteria grew from UVC-treated corneas, matching targeted antibiotics.
Laboratory efficacy study · 2025
Anti-biofilm efficacy of low-dose 265 nm UVC
15-second exposures killed 48-hour Pseudomonas biofilm within 4 hours.
Bring PhotonUVC Vet into your practice.
A 5-second, non-contact UVC treatment for corneal infections in dogs, cats and horses.