Assessment of corneal and conjunctival metaplasia by impression cytology during the treatment of canine keratoconjunctivitis sicca

Abstract

The purpose of this study was to assess the condition of cells in the conjunctiva and corneal epithelium prior to and during cyclosporine- or tacrolimusbased treatment of keratoconjunctivitis sicca (KCS). The study was performed on 40 dogs with KCS. The dogs were divided into two groups of 20 animals each. In Group I, 0.75% cyclosporine eye drops were administered three times a day, while in Group II 0.02% tacrolimus eye drops were administered twice daily. Additionally, each group was subdivided into three subgroups based on the results of the Schirmer I tear test (STT I). Evaluation of cellular metaplasia in the cornea and the palpebral and bulbar conjunctiva based on the Nelson–Adams scale was performed by impression cytology using Millipore round filters (Millipore VSWP 01300 DA) of 25 μm pore diameter applied to the studied area. Ophthalmological and cytological examinations were performed prior to the treatment as well as after one and two months of therapy. In both groups, a decrease in Nelson–Adams values was observed, corresponding to the increasing STT values [Rxy Spearman statistically significant correlation coefficient values between –0.75 (P < 0.001) and –0.45 (P < 0.01)]. The absence of goblet cells was observed in all dogs, regardless of the KCS stage. Goblet cells reappeared following both tacrolimus- and cyclosporine-based treatment in impression cytology specimens classified as 0 in the Nelson–Adams scale. The extent of corneal and conjunctival metaplasia in the course of tacrolimus- and cyclosporine-based treatment of KCS decreases with increasing STT values.