Repair of Severe Melting Ulcers with High Intensity UV-pen (18 to 60 mW/cm2) Corneal Cross-linking (CXL) and Amniotic Membrane Graft

Aims: To assess the efficacy of corneal collagen cross-linking (CXL) combined with amniotic membrane graft in the management of severe melting ulcers in the dog and cat using a UV-pen at high intensity.

Study Design: CXL for animal ulcers.

Place and Duration of Study: Kent, UK between June, 2016 and Dec. 2017; and between Feb, 2018 and April, 2018,

Methodology: Medical records of dogs and cats diagnosed with severe melting ulcers, managed with corneal CXL and Omnigen® graft during 2016 and 2017 were retrospectively reviewed. A specially designed small spot size (3 to 10 mm) UV-pen (CXL-100-PEN; made by New Vision Inc, Taiwan) with intensity range of 30 to 60 mW/cm2 was used for localized treatment. Following surgical preparation of the recipient cornea, the corneas were soaked with 0.1% riboflavin in 20% Dextran for 15 minutes followed by UV-A (365 nm) irradiation for 60 to 120 seconds, depending on areas treated. Following CXL, Omnigen® graft (1-3 layers) was sutured in the lesion with 8-0 polyglactin 910 (Vicryl; Ethicon). Ten dogs (10 eyes), and three cats (3 eyes) were included. Canine brachycephalic breeds were over represented (7/10 eyes). All eyes had been treated medically prior to surgery, with post-operative antibiotics based on culture-sensitivity results. Treated lesions included large, deep melting ulcers, with 3 extending to Descemet's membrane.

Results: Mean follow-up time was 8 to10 weeks (range 8-52 weeks). In all cases corneal melting was arrested, with improved ocular comfort within 3 to 6 days of treatment. In 11 eyes the cornea re-epithelialised within 8-20 days. Corneal perforation occured in 2 eyes between day 16 to 20. Good visual outcome was achieved in 10 cases; with extensive corneal pigmentation in one case, which stil remained visual.

Conclusion: CXL combined with an Omnigen® graft is a valuable technique for managing severe keratomalcia, resulting in a good visual outcome compared to traditional grafts.