Abstract
Purpose: :
Mucin balls are frequently present in subjects wearing silicone hydrogel (SH) contact lenses for (CW). This study determined if there is an association between mucin ball formation and corneal infiltrative events (CIEs) during CW with SH contact lenses.
Methods: :
Subjects (n=205) in the Longitudinal Analysis of Silicone Hydrogel Contact Lens Study (LASH Study) wore lotrafilcon A contact lenses for CW and were monitored over the course of 1 year for the development of a CIE. Mucin balls were graded by observation of their fluorescein pooled corneal indentations. Kaplan-Meier (KM) plots were used to provide the cumulative unadjusted probability of remaining CIE free stratified by presence or absence of mucin balls. Cox proportional hazards regression was used in univariate and multivariate analyses to model the probability of developing a CIE as a function of mucin ball formation.
Results: :
Over half (54.2%) of subjects displayed mucin balls during at least one visit and about one-third (32.8%) displayed repeated episodes. Mucin ball scores were correlated between the two eyes and weakly correlated with corneal curvature (p<=0.005). Univariate analyses revealed that the hazard for a CIE was 0.35 (95% confidence interval (CI) 0.19-0.68) if a single episode of mucin balls was detected and 0.17 (95% CI 0.06-0.43) if repeated episodes were detected. Upon multivariate analysis, repeated presence of mucin balls was associated with an 84% decreased risk of experiencing a CIE (hazard ratio 0.16, 95% CI 0.06-0.44).
Conclusions: :
Mucin balls, especially when present in a repeated fashion, are significantly associated with a decreased incidence of CIEs. The presence of mucin balls may represent a thicker, more concentrated, or viscous mucus layer which prevents upregulation of the immune response against bacterial antigens.
Clinical Trial: :
www.clinicaltrials.gov NCT00727402