Semi-quantitative lateral-flow immunochromatography kit for rapid diagnosis of inflammatory dry eye syndrome

Dry eye syndrome (DES), which is exacerbated by fine dust exposure and prolonged smartphone use, is increasingly prevalent. DES can be classified as inflammatory or non-inflammatory depending on the presence of ocular surface inflammation; accurate identification of inflammatory DES is important to guide appropriate therapy and reduce unnecessary antibiotic use. In inflammatory DES, cellular stress associated with increased tear osmolarity can trigger the release of cytokines and proteases, including matrix metalloproteinase-9 (MMP-9), onto the ocular surface. Here, we developed two lateral-flow immunoassay strips for rapid detection of tear MMP-9, a biomarker closely associated with dysfunctional tear syndrome (DTS). To semi-quantitatively assess disease severity, we designed a barcode-patterned strip in which gradient immobilization of capture molecules generates a discrete number of visible bands proportional to the analyte concentration, enabling intuitive visual semi-quantification. The system was tested in Version 1 and Version 2 depending on the capture agents and it was confirmed that there are differences in signal generation patterns based on the binding affinity between the reactive substances. The test was designed to determine the severity of inflammatory dry eye disease based on the amount of MMP-9 detected: Normal ≤200 pg (1 or no test line), Mild 200-600 pg (2 test lines), Severe ≥2000 pg (3 or more test lines). In the case of normal, only one test line is observed, and the limit of detection(LoD) is 50 pg. This instrument-free format may help clinicians estimate inflammatory DES severity at the point of care and support treatment decisions.