Mucins and Ocular Signs in Symptomatic and Asymptomatic Contact Lens Wear

Abstract

Lid wiper epitheliopathy (LWE) and lid parallel conjunctival folds (LIPCOF) are related to dry eye symptoms in contact lens wearers. Both clinical signs are assumed to be related to mechanical forces during blinking. As the mucus layer is a protector of the ocular surface tissue, this study investigates whether any alterations of mucins are detectable comparing symptomatic and asymptomatic soft contact lens wearers. Comfort was evaluated using the Contact Lens Dry Eye Questionnaire. Corneal staining, LWE, and LIPCOF were assessed in the right eyes of 50 (19 men, 31 women; mean age, 32.1 +/- 11.4 years) experienced lens wearers. The tear film was sampled using Schirmer strips pressed onto the temporal conjunctiva and from harvested contact lenses. Mucins were assessed in dot-blots and Western blots after electrophoresis on 1% agarose or 4 to 12% NuPAGE Gels. Non-parametric analyses were used to study differences between groups and correlations between objective tests, mucins, and symptoms. Thirty-one subjects were classified asymptomatic and 19 symptomatic by the questionnaire. LWE and LIPCOF were significantly increased in the symptomatic group (p < 0.035). MUC5AC reactivity was significantly decreased in symptomatics (p = 0.050). MUC4 was correlated to temporal LIPCOF and LWE, (r = -0.47 and -0.46; p < 0.01). MUC16 and MUC5AC correlated with corneal staining (0.36 < r < 0.53; p < 0.04). Symptomatic contact lens wearers exhibit significantly more LWE and LIPCOF, and decreased MUC5AC reactivity. LWE and LIPCOF are significantly correlated; this may reflect their common frictional origin. Increased friction might follow from insufficient mucins, or an altered composition of the resident mucins at the ocular surface. In this study, we show that decreased mucin production is associated with the severity of LWE and LIPCOF.