TREM2 deficiency resulted in corneal perforation (grade = + 4, Figure 1B right on the bottom), while the pupil of infected WT mice was partially or fully covered with dense opacity (grade = + 3, Figure 1B left on the bottom) at 5 days p.i. Since the disease pathogenesis of P. aeruginosa keratitis depends on both bacterial virulence and host inflammation, we first assessed the effects of TREM2 on bacterial load. This evidence concerns the gene TREM2 and keratitis.