Impression cytology in the evaluation of the treatment of dry eye in sjogren's syndrome patients

Aim: Impression cytology has been used to study conjunctival epithelium in healthy and in several diseases of the ocular surface. The present study was performed to evaluate the effect of the treatment of dry eye in Sjögren's syndrome patients with hypotonic or isotonic hyaluronate eye drops. Methods: 40 Sjögren's syndrome patients were divided in two groups and treated as follows: group 1 with hypotonic (150 mOsm/l) 0.4% hyaluronate eye drops; group 2 with isotonic 0.4% hyaluronate eye drops. The study drugs were commercially available eye drops. The eye drops were instilled six times a day for 90 days. Grading of subjective symptoms, clinical exams and conjunctival impression cytology were carried out at 0 and 15, 30, 90 days from the beginning of the study. For impression cytology, specimens were collected from the bulbar conjunctiva, fixed in a solution of glacial acetic acid, 40% formaldehyde, absolute ethanol and distilled water in the proportions of 1:1:14:6 respectively, then processed for the PAS-Papanicolaou stain. In each specimen, the following parameters were evaluated: 1) cellularity, 2) cell-to-cell contacts, 3) nucleus/cytoplasm ratio (N/C), 4) nuclear chromatin, 5) goblet cells distribution, 6) presence of keratinisation, 7) presence of inflammatory cells. Each parameter was given a score as follows: 0 = normal features; 1 = borderline features; 2 = abnormal features. For the parameters presence of keratinisation and of inflammatory cells a score of 3 was also considered, as they are signs of severe conjunctival alteration. The scores obtained for each parameter were summed to give a total score, on the basis of which the specimens were divided into three classes: class A (total score 0 - 3) normal features; class B (total score 4 - 6) borderline features; class C (total score > 6) abnormal features. For the statistical analysis the Student's t test, Mann-Whitney U test, and χ2 test were performed. Results: Symptoms were statistically significantly improved at day 15 in both groups but group 1 patients had a global score of all the clinical exams statistically significantly better than group 2 (p=0.02). In particular, the conjunctival impression cytology showed that group 1 had a statistically significant better total score than group 2 starting from day 15 and lasting throughout the study (p<0.02). Conclusion: Impression cytology was used as an indicator of conjunctival epithelial damage. It is noticeable that the method used to score the impression cytology specimens allowed us to study analytically seven parameters so it was possible to have an evaluation of the single aspects related to the epithelial conditions and to analytically differentiate the epithelial features following the different treatments. From the results of this study it is possible to assess that the treatment with hypotonic sodium hyaluronate eye drops gives a statistically significantly better improvement in clinical and cytological signs of the disease, compared with isotonic sodium hyaluronate at the same concentration.