Metalloproteinase-9 in the ocular surface of patients with implanted Boston type 1 keratoprosthesis.

Purpose: To characterize the presence of ocular surface inflammation, using matrix metalloproteinase 9 (MMP-9) as a marker, in the ocular surface of eyes with implanted Boston Keratoprosthesis type 1 (KPro).

Methods: Patients with implanted KPro at a single tertiary center were recruited to assess ocular inflammation. MMP-9 was measured using InflammaDry^® test in both eyes of each patient. The non-KPro eye served as control. Rate of positivity of MMP-9 was compared between groups. Possible associations between ocular surface inflammation and the development of postoperative complications were evaluated using univariate statistical analysis.

Results: Fifty eyes from 25 patients were included. The mean age was 50 years old. Non-inflammatory indications for KPro were predominant among patients. Eighty eight percent of KPro eyes had a positive test for MMP-9 while only 25% of control eyes were positive (p<001). The most common complications were retroprosthetic membrane, epithelial defects, and sterile corneal melt. The presence of a strong positive result was associated to a higher frequency of complications (80% of eyes) compared to a faint positive test (54%) and a negative test (33%).

Conclusion: The KPro device appears to increase MMP-9 levels in the ocular surface. High MMP-9 levels may be associated with higher risk of complications. MMP-9 testing can be useful to assess subclinical ocular surface inflammation with a potential role in the postoperative care of KPro patients.