Clinique Vétérinaire des Halles, Strasbourg, France.
Vet Ophthalmol 2014;17:241–9.
James Oliver’s review: Corneal pigmentation is a relatively common cause of visual deficits in several breeds of dogs. There are several potential aetiological causes of corneal pigmentation, including keratoconjunctivitis sicca and chronic superficial keratitis. Corneal pigmentation may also be breed-related, occurring in the absence of obvious tear film deficiencies or inflammation, particularly in the Pug breed. Treatment of corneal pigmentation usually includes aggressive topical medical therapy with immunosuppressants such as cyclosporine A or corticosteroids, but the response is highly variable. Surgical treatment via superficial keratectomy can also be attempted when pigmentation is severe enough to cause blindness, but it is associated with complications – scarring, inflammation, and melting corneal ulceration.
The author of this prospective study sought to evaluate the effects of cryotherapy on corneal pigmentation. Nine dogs (16 corneas) were included that had corneal pigmentation as a result of either chronic superficial keratitis or keratoconjunctivitis sicca that was unresponsive to medical therapy. Under general anaesthesia, a cryogen (95% dimethylether, 3% isobutene, and 2% propane) was applied to the pigmented areas of each cornea using two rapid-freeze–slow-thaw cycles. A grading scheme and clinical photographs were used to measure corneal pigmentation before cryotherapy and for ≥60days postoperatively. Any complications of cryotherapy were also recorded.