Abstract
Purpose: :
Keratoconus (KC) is a corneal ectasia with unknown etiology and with presumed association of extended contact lens (CL) wear. Our purpose was to study the effects of prolonged CL wear on different tear mediators in patients with KC.
Methods: :
In this cohort study, nonstimulated tear fluid samples were collected, at regular time intervals over 6 weeks, from 10 patients (10 eyes) with KC and 10 patients (19 eyes) with ametropia (AM) prior to and during continuous wear of CL. Patients with KC had worn rigid gas permeable (RGP) CL and patients with AM had worn silicone hydrogel CL, respectively. The concentrations of IL-6, IL-8, IL-13, RANTES, MMP-9, MMP-13, TIMP-1, NGF, EGF were measured by the cytometric bead array technology. Release of soluble mediators was calculated from their concentrations and the volume of tears collected for 2 minutes.
Results: :
Six weeks long RGP CL wear in KC patients caused threefold increase in MMP-9 release with a decrease of TIMP-1, RANTES and IL-13 levels (2-, 6- and 22-fold, respectively). The linear trend over time for IL-13 showed a significant decrease (p=0.047). Prior to CL wear (baseline) the release of NGF was lower (p=0.05), RANTES and IL-13 were 4.5-fold higher; MMP-9, TIMP-1, IL-8 and IL-6 were moderately higher in tears of KC eyes compared to AMs. At week 6 a significant difference between the two groups was found for MMP-9 release (p=0.008). Significantly lower level of IL-8 was found in AMs at week 6 (p=0.044). Between the groups the linear trend over time showed a significant difference for MMP-9 (increase in KC, decrease in AM, p=0.02) and for RANTES (decrease in KC, slight increase in AM p=0.03).
Conclusions: :
The level of various soluble mediators in tears of patients with corneal ectasia with extended CL wear may contribute to the pathology of this disease and can have a predictive value in disease progression. According to our best knowledge this is the first comprehensive high-throughput study of real time follow up of selected soluble mediators.
Keywords: keratoconus • cornea: basic science • contact lens