Substance P Level in Tears as a Potential Biomarker for Contact Lens Discomfort

ABSTRACT

Purpose: To analyze the effects of contact lens (CL) wear, time of the day, and CL discomfort (CLD) on clinical signs, tear inflammatory mediators and substance P.

Methods: Thirty symptomatic and 30 asymptomatic CL wearers attended two visits (morning and afternoon) on two days (non-CL and CL wearing days). Comfort, meniscus area, noninvasive breakup time (NIBUT), tear collection, hyperemia, lid parallel conjunctival folds, fluorescein staining, and sensitivity were performed. The tear levels of 23 inflammatory mediators and substance P were measured.

Results: Comfort, meniscus area, NIBUT, and MMP-9 were lower while conjunctival staining and EGF higher (p ≤ 0.015) on the CL wearing day. Comfort, IL-8/CXCL8, and VEGF were lower while EGF, IP-10/CXCL10, and MCP-1/CCL2 higher (p ≤ 0.047) in the afternoon. Comfort was lower and substance P higher (p ≤ 0.006) in symptomatic wearers.

Conclusion: Substance P may be implicated in CLD etiology; its role and potential application as a biomarker should be further studied.

Keywords:

• Contact lens
• discomfort
• inflammation
• mediator
• substance P

Declaration of interest

The authors report no conflicts of interest. The authors alone are responsible for the content and writing of the paper.

Additional information

Funding

This work was supported by the Junta de Castilla y León and European Social Fund [EDU/310/2015].