Upregulation of matrix metalloproteinase in tear fluid of patients with recurrent corneal erosion

Purpose: To investigate gelatinase [matrix metalloproteinase (MMP)-2 and MMP-9] expression in the tear fluid of patients with recurrent corneal erosion (RCE). Methods: Eleven patients with RCE, three patients with traumatic corneal erosion, and 10 control individuals were enrolled in this study. Tear samples from RCE eyes were obtained once, either at the time of recurrence (onset-phase samples, seven samples), or during the remission period (remission-phase samples, four samples). Tear samples from the nonaffected fellow eyes of the RCE patients were also examined once (fellow-eye samples, ten samples from ten patients). In addition, three samples from three patients with traumatic corneal erosion and ten samples from ten control individuals were obtained as well. Tear samples were collected by a modified Schirmer test I method and analyzed by gelatin zymography. Results: Neither the active form of MMP-2 nor that of MMP-9 was detected in the samples from traumatic corneal erosion patients and control individuals. Both active MMP-2 and active MMP-9 were detected in all seven onset-phase samples. Active MMP-2 and active MMP-9 were detected in three of the four remission-phase samples. Although none of the ten fellow eyes had a history of RCE, active MMP-2 and active MMP-9 were detected in three fellow-eye samples. Conclusions: Gelatinase expression was upregulated in the tear fluid of RCE patients. The presence of gelatinase in the affected eye during the remission phase as well as in the nonaffected fellow eye indicates that gelatinase expression in the tear fluid may be related to the recurrence of corneal erosion.