MMP9 and Trichiasis: Preoperatively, clinically visible conjunctival inflammation and scarring are associated with increased expression of pro-inflammatory cytokines (interleukin-1β, CXCL5, and S100A7) and MMPs (MMP-7, MMP-9 and MMP-12).16, 21 Similarly, increased expression of these factors has also been reported in patients following trichiasis surgery.23