The Correlation between Loosely Adherent sPLA2IIA in Symptomatic and Asymptomatic Non-Ionic Silicone Hydrogel Lens Wearers

Abstract

Purpose: : To evaluate the difference in the levels of secretory phospholipase A₂ Type IIA (sPLA₂IIA) in the tear envelope collected from symptomatic (i.e. reports decreased comfort at replacement time) and asymptomatic patients.

Methods: : In this study, lenses were collected from the symptomatic and asymptomatic patients aseptically and stored dry at below -20 ºC. All patients wore the same non-ionic silicone hydrogel lens material and used the same lens care regimen. Lenses were equilibrated to ambient temperature and rinsed in 2 mL of phosphate buffered saline for 5 minutes with agitation. The rinsate from each lens was subjected to a sandwich ELISA by introduction to a plate coated with a monoclonal antibody specific for sPLA₂IIA. The plate was washed and an Acetylcholinesterase (ACHe); Fab’conjugate was added to the plate which selectively binds to a different epitope on the sPLA₂IIA molecule. Finally, the enzymatic activity of ACHe was measured by adding a reagent containing the ACHe substrate and reading the plate at a wavelength of 420 nm by spectrophotometry.

Results: : Symptomatic and asymptomatic patients exhibited statistically similar levels of sPLA₂IIA in the tear envelop of 22.6±10.8 and 20.7±7.8 ng/Lens, respectively (p = 0.413) (student’s t-test, α = 0.05).

Conclusions: : sPLA₂IIA is known to hydrolyze fatty acids generating free arachidonic acid and lysophospholipids, the precursors of pro-inflammatory lipid mediators. Recent studies have reported elevated levels of sPLA₂IIA in the tears of intolerant contact lens wearers and increased sPLA₂IIA activity in tears from dry eye disease patients. Our findings, which focused on comfort at replacement time, suggest that there is no difference in the levels of sPLA₂IIA in the tear envelope between symptomatic and asymptomatic patients as defined by the criteria of this study. However, it is possible that the relationship between comfort and sPLA₂IIA levels is multi-factorial and therefore, future efforts should be in evaluating the interdependence with other biomarkers.

Keywords: contact lens