Tear Matrix Metalloproteinases and Myeloperoxidase Levels in Patients With Boston Keratoprosthesis Type I

Purpose To investigate the tear levels of matrix metalloproteinases (MMPs), myeloperoxidase (MPO), and tissue inhibitor of metalloproteinase-1 in eyes after Boston keratoprosthesis type I (B-KPro) implantation and to correlate these markers with the established B-KPro prognostic categories. Methods Tear washes were collected from 40 patients (7 with autoimmune disease, 2 with chemical burn, and 31 with other noncicatrizing diagnoses). Tear levels of MMPs, MPO, and tissue inhibitor of metalloproteinase-1 were quantified using multianalyte bead-based enzyme-linked immunosorbent assays. The total MMP activity was determined using a fluorimetric assay. The analytes were compared to the underlying diagnosis and other clinical factors. Results The MMP-8, MMP-9, and MPO levels were markedly elevated in the eyes with B-KPro (80 ± 31, 291 ± 77, and 244 ± 33 pg/μg, respectively). Chemical burn was associated with significantly higher tear MMP-8 (474 ± 376 pg/μg) and MMP-9 levels (1300 ± 635 pg/μg) compared with noncicatrizing diseases (MMP-8: 41 ± 15 pg/μg, P = 0.02 and MMP-9: 196 ± 57 pg/μg, P = 0.02) and higher MMP-9 levels compared with autoimmune diseases (MMP-8: 96 ± 65 pg/μg, P = 0.21 and MMP-9: 306 ± 196 pg/μg, P = 0.04). Similar analyte levels were observed in the B-KPro eye and the contralateral non-B-KPro eye of patients with bilateral diseases. MMP-8, MMP-9, and total MMP activities correlated strongly with each other. Conclusions In the eyes with B-KPro, tear MMP-8 and MMP-9 levels seem to be related to the underlying ocular surface pathology and not significantly influenced by the presence of the prosthesis.