Abstract
Purpose:
To describe three clinical cases of immune-mediated keratitis (IMMK) following treatment with topical carbonic anhydrase inhibitors (CAI) and histopathology of two additional cases suspected of having this disease.
Methods:
The complete medical records of three canine patients with IMMK following treatment with topical CAI were examined retrospectively. The past medical and ophthalmic histories were reviewed, and the time to onset of clinical signs after initiation of CAI therapy and their resolution following CAI discontinuation were recorded. Two cases with severe IMMK that received long-term CAI treatment which was not discontinued were examined histologically and stained with hematoxylin and eosin, as well as CD-20, CD-79a, CD-3 and IgG to phenotype the corneal inflammatory response.
Results:
In all cases, the mean time to initial ocular signs following treatment with CAI was 233 days (range 7-672), and the mean time to severe signs was 355 days (range 133-679). Mean time to discontinuation of therapy in the three clinical cases was 284 days (range 161-433). Improvement was seen within 2-4 days of withdrawal, and signs resolved within 12-25 days. Mean follow-up time after discontinuation of CAI was 23 months (range 12-42). All five cases were refractory to anti-inflammatory medication. Histopathology showed a biphasic anterior stromal and intraepithelial lymphoplasmacytic inflammatory infiltrate and epithelial IgG deposition, most consistent with a hypersensitivity response.
Conclusions:
Topical CAI associated keratitis in dogs is a non-steroid responsive immune-mediated disease that improves soon after CAI discontinuation. This is the first report of local side-effects following topical CAI in veterinary medicine.
Keywords: 443 carbonic anhydrase •
573 keratitis •
479 cornea: clinical science