To investigate the correlation between the matrix metalloproteinase-9 (MMP-9) concentration, and subjective symptoms and objective signs in dry eye patients. Methods

We retrospectively reviewed the medical records of 134 eyes of 67 patients who were diagnosed with dry eye disease. The results of tear MMP-9, which were conducted at a care testing facility, were defined as negative (N), equivocal (E), weak positive (W), positive (P) or strong positive (S). Using three methods with different classification ranges, MMP-9 results were classified into a negative group or positive group. The objective signs of dry eye disease, including tear break-up time (TBUT), tear volume measured by Schirmer's test, degree of corneal erosion estimated by the Oxford stain score (OSS), and ocular surface disease index (OSDI) as the subjective symptom, were recorded. The differences of indices were compared between the negative and positive groups. Results

There was no significant difference of the TBUT, Schirmer's test, or OSS between the MMP-9 negative and positive groups. Also, the percentage of females was significantly higher in the negative group compared with the positive group regardless of the classification methods (all, p < 0.05). When the MMP-9N alone was classified as a negative group, the OSDI score was significantly higher in the positive group when compared to that of the negative group ( p = 0.009). Conclusions

The measurement of MMP-9 in patients with dry eye disease may be helpful in predicting subjective symptoms of dry eye disease.