Clinical improvement of ocular surface parameters in dry eye patients following treatment with urea/crosslinked-hyaluronate eyedrops correlates with the secretion of MUC-4

Abstract

ABSTRACT Objectives to assess the ocular surface status and patient’s satisfaction before and after treatment with urea/crosslinked hyaluronate (U-HACL) tear substitute in dry eye (DE) patients. Methods 17 DE patients were included in the study. They instilled U-HACL drops 3 times/day for two months. Symptoms (by OSDI questionnaire and VAS), osmolarity, tear film (through Schirmer test and tear film break-up time), corneal and conjunctival damage (with NEI and van Bijsterveld scores), impression cytology (number of PAS positive cells and MUC-4 immunostaining) and tear sampling were analyzed pre- and post-treatment. Results After the treatment, there was a significant improvement of VAS (7.16±2.59 vs. 3.94±2.23), OSDI (56.96±25.97 vs. 29.94±20.15), Schirmer (8.22±6.86 vs. 10.66±6.92), TFBUT (3.16±2.28 vs. 5.55±2.47), NEI (7.16±2.50 vs. 2.88±2.80) and van Bijsterveld (10.27±4.25 vs. 6.5±3.79) score, p<0.01. No significant changes in osmolarity were found. There was a significant increase of PAS positive cells and in the expression levels of MUC-4 (respectively, 44.21 ± 14.8 vs. 67.0 ± 10.1 and 49.79 ± 20.0 vs. 75.9 ± 20.7), p<0.01. Conclusion Patients showed significant clinical improvement following the administration of U-HACL eye drops. In particular, the rise of MUC-4 expression probably contributed to the increase in ocular wettability and amelioration of clinical parameters.