Changes in conjunctival epithelial cells after treatment with 0.2% xanthan gum eye drops in mild-moderate dry eye.

Purpose: To study the effects of xanthan gum eye drops on the ocular surface and conjunctival cytology of patients with mild-moderate dry eye. Methods: This prospective, double-masked, controlled trial included 30 patients (age > 60 and Ocular Surface Disease Index score >12 and <33), divided into two groups of 15 subjects and treated with 0.2% xanthan gum eye drops (group 1) or 0.5% carboxymethylcellulose (group 2) qid. After a run-in period with saline qid, patients were evaluated by Ocular Surface Disease Index questionnaire, clinical assessment, and impression cytology at baseline (T0) and after 1 month (T1). For impression cytology, cellularity, cell-to-cell contacts, nucleus/cytoplasm ratio, chromatin aspect, goblet cells distribution, keratinization, and the presence of inflammatory cells were considered. Parameters were scored from 0 (no alterations) to 3 (evident alterations). For statistical analysis, Student's t-test, Wilcoxon rank-sum test, and Mann-Whitney U-test were used. Results: Clinically, after 1 month of treatment, group 1 showed an improvement of corneal stain (T0 = 1.1 +/- 1.4; T1 = 0.5 +/- 0.7; p = 0.03) and a reduction of Schirmer I test (T0 = 9.8 +/- 6.1; T1 = 5.9 +/- 4.1; p = 0.001). In group 2, no differences were found between T0 and T1 for all the clinical tests. For impression cytology, in group 1 cellularity (T0 = 0.6 +/- 0.5; T1 = 0.3 +/- 0.5; p = 0.05), chromatin aspect (T0 = 1.2 +/- 0.4; T1 = 0.8 +/- 0.5; p = 0.01), keratinization (T0 = 1 +/- 0.7; T1 = 0.5 +/- 0.5; p = 0.03), and total score (T0 = 5.8 +/- 1.3; T1 = 3.6 +/- 1.7; p = 0.003) were significantly ameliorated, while in group 2 only total score improved significantly (T0 = 5 +/- 1.4; T1 = 4.3 +/- 1.5; p = 0.01). The comparison between groups showed significant amelioration for keratinization in group 1 at T1 (p = 0.02). Conclusion: The treatment with xanthan gum, a molecule with anti-oxidant and mucoadhesive properties, ameliorated conjunctival epithelium of mild-moderate dry eye patients better than carboxymethylcellulose.