Table 3.

Changes in matrix metalloproteinase-9 levels before and after eyelid debris debridement and meibomian gland expression in patients with moderate and severe meibomian gland dysfunction

Parameters	Before treatment	4 weeks after the treatment	P value
MMP-9 levelsa	2.58 (0.20)	1.92 (0.26)	0.029
MMP-9 positivityb	20 (83.3%)	12 (50.0%)	0.014

MMP-9 matrix metalloproteinase-9

MMP-9 levels were measured based upon the changes in the intensity of color on a scale of 0 to 4, as follows: 0, none; 1, trace; 2, weak positive; 3, positive; and 4, strong positive

^aResults are presented as mean (standard error) and P values are from linear mixed model

^bχ² test: n (%, proportion for positive result: weak, positive, and strong positive)