Is contact lens discomfort related to meibomian gland morphology?

PURPOSE: To examine the relationship between contact lens (CL) discomfort and meibomian gland (MG) morphology assessed by a semi-objective software in subjects without an alteration of MG function (meibum quality and expressibility). METHODS: Nineteen symptomatic (CLDEQ-8 ≥ 12) CL wearers, 19 asymptomatic (CLDEQ-8 < 12) wearers, and 22 non-wearers were recruited. Upper and lower eyelid meibography images were taken and the following parameters were analysed using a semi-objective software in the central 2/3 of each eyelid: number of MG, number of partial MG, percentage of MG loss and percentage of tortuosity. One-way ANOVA or Kruskal-Wallis H test were used for comparisons among groups. The relationships between CLDEQ-8 and MG morphology parameters were analysed using the Spearman correlation coefficient and multivariable linear regression models. RESULTS: No significant differences were found among groups in the MG morphology of the upper or lower eyelids. In all CL wearers, a significant correlation with CLDEQ-8 was found in the upper eyelid for the number of MG (rho = 0.47, p = 0.003). In symptomatic wearers, significant correlations with CLDEQ-8 were found in the lower eyelid for the number of partial MG (rho = 0.49, p = 0.03) and the percentage of partial MG (rho = 0.61, p = 0.005). In all CL wearers, multivariable models were fitted to explain CLDEQ-8 score including the number of MG, the number of partial MG and the percentage of MG loss from the lower eyelid (R2 = 0.19; p = 0.007), and the number of MG from the upper eyelid (R2 = 0.19; p = 0.001). In symptomatic wearers, a model was fitted including the percentage of MG loss from the lower eyelid (R2 = 0.30; p = 0.016). CONCLUSIONS: Alterations of MG morphology, without clinically apparent alteration of MG function, can be involved in causing CL discomfort and influence the degree of symptoms. The differences in findings between eyelids indicate the need to monitor both eyelids, especially the lower one, in CL wearers.