The effect of UV-blocking contact lenses as a therapy for canine chronic superficial keratitis

Objective To evaluate the effect of UV‐blocking soft contact lenses in treatment for chronic superficial keratitus (CSK). Methods Twenty six dogs with CSK were treated continuously with UV‐blocking contact lenses for 6 months. A contact lens was placed on one eye of each dog; the other eye remained without a lens as a control eye. After this primary study, five of the dogs were further treated and they wore then contact lenses in both eyes. Continuously, all patients were concurrently treated topically with cyclosporine. The contact lenses were changed every 4 weeks and an ophthalmic examination performed. Evaluation criteria included corneal alterations as pigmentation, edema, pannus and vascularization. To determine the transmittance characteristics of the contact lenses before and after use, 32 contact lenses were measured with a UV‐vis‐NIR spectrophotometer. Results Pigmentation increased in eyes wearing lenses and in control eyes over the evaluation period of 6 months. Corneal edema increased in the eyes wearing lenses, but remained unaffected in the control eyes. A significant difference in the incidence of pannus and the extent of corneal vascularisation could not be evaluated. Adverse effects were noted in six cases (corneal edema and vascularisation, conjunctivitis, blepharospasm). All new lenses studied reduced UV‐radiation to a safe level, whereas used lenses did not maintain their transmittance characteristics. Conclusions No positive effect of UV‐blocking contact lenses could be proven with the study design used.