In 2013, the Food and Drug Administration (FDA) approved a lateral-flow diagnostic test (InflammaDry, Rapid Pathogen Screening Inc., Sarasota, FL, USA) that measures the concentration of matrix metalloproteinase-9 (MMP-9) for the diagnosis of dry eye.23,24 The concentration of MMP-9 has been shown to be elevated in the tears of patients with dry eye disease.25 However, this assay requires multiple sample processing steps and gives a binary response limiting its value in determining severity. This evidence concerns the gene MMP9 and dry eye syndrome.