The article, the matrix metalloproteinase 9 point-of-care test in dry eye by Lanza et al., discusses the role of ocular surface matrix metalloproteinase 9 (MMP-9) in dry eye and choosing suitable treatments based on MMP-9 levels measured using a point-of-care test.
Dry eye is a common ocular condition that affects 5–30% of the population and has a major impact on quality of life. It's a multifactorial ocular surface and tear disease with symptoms such as pain, tear instability, and visual disturbance. However, the subjective symptoms of dry eye poorly correlate with the current standard for diagnostic tests, resulting in the need to develop better objective tests for the diagnosis of dry eye. Despite the prevalence of dry eye, only about two-thirds of patients who report dry eye symptoms are diagnosed with the condition. Moreover, none of the available screening tests has been shown to accurately estimate the course of dry eye disease or its treatment response.
Inflammation is known to be a significant component in the pathophysiology of dry eyes. However, it's unclear whether all patients with dry eye disease experience ongoing inflammation and, as a result, may benefit from anti-inflammatory treatment. Only 39% of patients treated with 0.1 percent topical cyclosporine emulsion for 6 months had a satisfactory response to therapy. In a different prospective study of patients with delayed tear clearance, people were treated with nonpreserved topical methylprednisolone for three weeks, three times daily. The study showed that the therapy resulted in the improvement of ocular surface inflammation in some but not all participants. After treatment, 80% of patients showed a decrease in bulbar conjunctival injection, reduced vital dye staining, and a decrease in tarsal papillary response.
Prior studies have shown that inflammation is a major aspect of dry eye disease, but the fact that not all patients respond to therapy suggests that not all dry eye patients have severe inflammation requiring anti-inflammatory treatment. Although it's hard to compare research findings due to differences in research approaches, the frequency of response after corticosteroid treatment was higher than after cyclosporine treatment. These results highlight the complexity and multifactorial nature of dry eye disease aetiology, as well as the need for better diagnostic tests to help guide treatment options. One such test that can aid in adequate therapeutic selection is the detection of elevated MMP-9 on the ocular surface.
Lanza, N. L., Valenzuela, F., Perez, V. L., & Galor, A. (2016). The Matrix Metalloproteinase 9
Point-of-Care Test in Dry Eye. The ocular surface, 14(2), 189–195.