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Alice Kim, Cameron K Postnikoff, Kelly K Nichols; Nonpharmaceutical eye wash may reduce Matrix Metalloprotease-9 (MMP-9) in dry eye. Invest. Ophthalmol. Vis. Sci. 2020;61(7):100.
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Past studies have revealed the inflammatory nature of the closed eye environment, and millions of inflammatory mediators are recruited to the ocular surface during sleep. Matrix metalloprotease-9 (MMP-9) has been shown to degrade collagen on the ocular surface when overexpressed. We hypothesize that a nonpharmaceutical eye wash immediately upon awakening may serve as an effective means of reducing MMP-9 on the ocular surface and thus alleviating dry eye symptoms.
Thirty-six normal and 36 dry eye subjects were randomized and instructed to perform a phosphate buffer saline eye wash and eye wash collection on both eyes immediately upon awakening on two occasions, either daily (treatment) or once every two weeks (control). Supernatants from the eye washes were maintained, and MMP-9 quantification was performed using a Quantikine ELISA (R&D Systems, Minneapolis, MN). MMP-9 concentration was normalized to total protein using a BCA protein assay (ThermoFisher, Waltham, MA). The MMP-9 concentrations of samples were read at 450 nm using a spectrophotometer. Statistical analysis using a two-sample t-test was performed comparing MMP-9 levels at baseline between normal and dry eye groups before and after treatment.
On average, the MMP-9 concentrations decreased from 1.163 to 0.562 ng/mL for the normal group and 0.796 to 0.525 ng/mL for dry eye subjects after treatment. Normalized MMP-9 concentrations at baseline were higher in dry eye subjects. No significant difference was observed between treatment and control subjects at either time point.
These findings demonstrate that MMP-9 concentrations before the eyewash period were higher for dry eye than normal groups. These results are consistent with the hypothesis that MMP-9 may be higher in subjects experiencing dry eye symptoms as compared to normal subjects. Further experiments on related inflammatory mediators are needed to explore the mechanisms of inflammatory dry eye, determine a more easily manageable route of diagnosis and treatment, and determine the effectiveness of a daily eye wash in reducing inflammatory mediators on the ocular surface with consistent use.
This is a 2020 ARVO Annual Meeting abstract.
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