Evaluation of Corneal and Conjunctival Epithelium with the Use of Impression Cytology in Mixed-breed Dogs Diagnosed with Keratoconjunctivits Sicca

The study was conducted on 18 mixed-breed dogs, aged 2.5 to 10 years. All patients were diagnosed with immunemediated keratoconjunctivitis sicca (KCS) during an ophthalmological examination. A total of 33 corneas and conjunctivae were affected by the disease. Based on the results of Schirmer’s test (STT), the patients were divided into three equal groups. In group I, the STT score was within the range of 0-5 mm, in group II 6-10 mm, and in group III 11-14 mm. Impression cytology of the bulbar conjunctiva and cornea were performed with the use of round millipore filters applied over the examined surfaces. One disk was used to sample material from the superior and inferior temporal quadrants of the cornea and the adjacent bulbar conjunctiva, the second disk was applied on palpebral conjunctiva surface of the palpebra superior. The disks were subsequently stained using the PAS method. The cytological analysis of corneal and conjunctival epithelial cells was performed according to the 4 grade NelsonAdams index. In the impression cytology preparations from patients with advanced stages of KCS, a significant progress of epithelial cell metaplasia in the cornea and conjunctiva was observed – classified as grade 3. It was observed also that the degree of corneal and conjunctival cell metaplasia advancement in KCS patients increased with the decrease of STT values. The presence of goblet cells was not observed in either bulbar or palpebral conjunctiva, regardless of KCS advancement. Impression cytology is a simple and non-invasive method of examining the conjunctival and corneal epithelium and allows close monitoring of the disease process in dogs diagnosed with KCS.