Ulcerative keratitis associated with qualitative tear film abnormalities in cats

Abstract

Three cats with indolent corneal ulcers and one cat with bilateral corneal sequestration and normal aqueous tear production were found to have rapid tear break-up times (BUTs). Tear BUTs in clinically affected cats averaged 2.5 +/- 1.29 s and 2.33 +/- 0.58 s for the right and left eyes, respectively. Palpebral conjunctival biopsies were harvested from consistent sites from each eye of affected cats (n = 7 affected eyes), and age-and breed-matched controls (n = 2 unaffected eyes). Light microscopy revealed a marked decrease to complete absence of conjunctival goblet cells (average goblet cell (GC):epithelial cell (EC) density = 18:50), conjunctival epithelial dysplasia, squamous metaplasia, and neutrophilic and mononuclear cell submucosal infiltration in affected cats. Specimens from the control cats had an average GC:EC density of 34:50, and minimal submucosal inflammatory infiltrate. The corneas (n = 7 eyes) healed following surgical keratectomy with (n = 2 eyes) or without (n = 1 eye) conjunctival pedicle flaps, superficial keratectomy and striate keratotomy with (n = 2 eyes) or without (n = 2 eyes) third eyelid flaps, and mucinomimetic tear supplementation (n = 5 eyes). Goblet cell regeneration was confirmed after 5 months of mucinomimetic supplementation (n = 2 eyes). The etiology for these mucin deficiencies remains unknown.