A novel Schirmer Strip-Based Tear Matrix Metalloproteinase Measurement in Dry Eye Evaluation.

Unlabelled: Dry eye disease is a multifactorial disorder of the ocular surface with increasing global prevalence, yet no universally accepted "gold standard" exists for its diagnosis or severity assessment. Tear matrix metalloproteinase 9 (MMP-9) is widely recognized as a valuable biomarker for dry eye, yet there remains a critical need for a simple, accurate, and broadly applicable method for its quantification. This study aims to develop and evaluate a Schirmer strip-based Eu-time resolved fluorescence immunochromatography (Eu-TRFICO) method for the quantitative detection of MMP-9 in tears. The method was optimized and evaluated for sensitivity, repeatability, and homogeneity using MMP-9 standards, and its diagnostic performance was assessed in both normal subjects and dry eye patients. The method demonstrated a sensitivity of 0.25 ng/mL and exhibited good repeatability across varying Schirmer strip saturation levels. In a cohort of 162 participants (121 dry eye patients and 41 normal subjects), the test achieved a sensitivity of 74.17% and a specificity of 77.5% for dry eye diagnosis, based on the Chinese Expert Consensus on Dry Eye: Examination and Diagnosis (2020). The area under the curve (AUC) was 0.8275 with a cutoff value of 150.67 ng/mL. Additionally, tear MMP-9 levels measured using this method strongly correlated with therapeutic responses in dry eye patients. This approach offers a precise and practical method for MMP-9 quantification in tears, enhancing its potential utility in the diagnosis and monitoring of dry eye disease.

Purpose: The diagnosis and evaluation of dry eye require easy-to-use, precise, and consistent tools in clinical setting. Matrix metalloproteinase 9 (MMP-9) has been proven to be a reliable indicator of dry eye inflammation. The aim of this study is to establish an Eu-time resolved fluorescence immunochromatography (Eu-TRFICO) method for quantitative detection of MMP-9 in human tear based upon widely used Schirmer strips.

Methods: The Eu-TRFICO method for Schirmer strip-based tear MMP-9 measurements were optimized and assembled. The sensitivity, repeatability and homogeneity were evaluated using MMP-9 standard dilutions. The diagnostic and treatment monitoring performance were evaluated in both dry eye patients and normal subjects.

Results: The standard curve equation was y = 0.0037+8.0692 / [1+ (x/188.322)] (R2 = 0.99998), and the sensitivity was 0.25 ng/mL. The Schirmer strip-based MMP-9 measurements showed acceptable repeatability and homogeneity with different saturation length in both low and high standard solutions. A total of 162 participants (162 eyes) were enrolled in this study, including 41 normal and 121 dry eye subjects. This method exhibited a sensitivity of 74.17% and specificity of 77.5% for dry eye diagnosis, with an AUC value of 0.8275, and cutoff value of 150.67 ng/mL, using normal subjects as negative control. The tear MMP-9 concentrations monitored with this method correlated well with the therapeutic response in dry eye patients.

Conclusions: This study developed Eu-TRFICO Schirmer strips with high sensitivity, specificity, precision, and satisfactory clinical testing performance, which provides a convenient and quantitative option for clinical testing of tear MMP-9 in dry eye patients.