Corneal cross-linking in 9 horses with ulcerative keratitis

Abstract

BackgroundCorneal ulcers are one of the most common eye problems in the horse and can cause varying degrees of visual impairment. Secondary infection and protease activity causing melting of the corneal stroma are always concerns in patients with corneal ulcers. Corneal collagen cross-linking (CXL), induced by illumination of the corneal stroma with ultraviolet light (UVA) after instillation of riboflavin (vitamin B2) eye drops, introduces crosslinks which stabilize melting corneas, and has been used to successfully treat infectious ulcerative keratitis in human patients. Therefore we decided to study if CXL can be performed in sedated, standing horses with ulcerative keratitis with or without stromal melting.ResultsNine horses, aged 1 month to 16 years (median 5 years) were treated with a combination of CXL and medical therapy. Two horses were diagnosed with mycotic, 5 with bacterial and 2 with aseptic ulcerative keratitis. A modified Dresden-protocol for CXL could readily be performed in all 9 horses after sedation. Stromal melting, diagnosed in 4 horses, stopped within 24 h. Eight of nine eyes became fluorescein negative in 13.5 days (median time; range 4–26 days) days after CXL. One horse developed a bacterial conjunctivitis the day after CXL, which was successfully treated with topical antibiotics. One horse with fungal ulcerative keratitis and severe uveitis was enucleated 4 days after treatment due to panophthalmitis.ConclusionsCXL can be performed in standing, sedated horses. We did not observe any deleterious effects attributed to riboflavin or UVA irradiation per se during the follow-up, neither in horses with infectious nor aseptic ulcerative keratitis. These data support that CXL can be performed in the standing horse, but further studies are required to compare CXL to conventional medical treatment in equine keratitis and to optimize the CXL protocol in this species.

Corneal cross‐linking (CXL)—A clinical study to evaluate CXL as a treatment in comparison with medical treatment for ulcerative keratitis in horses

“…Calculations of ulcer area reduction per day revealed that wound healing progressed almost identically in both groups. The study thus indicates that CXL is probably not associated with adverse effects on wound healing rates in the horse cornea, which is in agreement with our previous study …”

“…CXL increases the bio‐mechanical strength and stabilizes the cornea by forming new cross‐links in the corneal stroma between collagen fibers and between proteoglycan core proteins, thus making it more resistant to melting and bacterial attack through steric hindrance . Hence, it has been used to treat corneal melting in humans, cats, dogs, and horses …”

Corneal cross‐linking as a treatment for corneal dystrophy with secondary bacterial infection in a Friesian horse

“…Corneal cross‐linking has been described as treatment alternative for pellucid marginal degeneration in human patients and is a cost‐effective treatment modality that can be performed on a sedated standing horse, provided that the disease is detected early when corneal stromal loss is still limited . A minimum corneal thickness of 400 µm to allow sufficient absorption of the UV‐A radiation in the riboflavin saturated stroma is recommended to safely perform CXL and avoid endothelial, lens and retinal damage .…”

Keratomykose beim Pferd

“…Eine neue und sehr interessante Behandlungsmöglichkeit, die ursprünglich zur Therapie des Keratokonus und aktuell auch gegen infektiöse Hornhautentzün-dungen eingesetzt wird, ist die CXL-Technik (corneal Collagen Crosslinking -CXL) [8,12]. Bisher wurden jedoch zu wenige Pferde mit dieser Technik behandelt, um die Ergebnisse objektiv beurteilen zu kön-nen.…”