Epitropoulos et al. sought out to assess the effect of oral re-esterified ω-3 fatty acids on tear osmolarity, matrix metalloproteinase-9 (MMP-9), tear break-up time (TBUT), Ocular Surface Disease Index, fluorescein corneal staining, Schirmer score, MGD stage and ω-3 index in subjects with dry eyes and confirmed MGD (Table 2) [46]. This evidence concerns the gene MMP9 and Keratoconjunctivitis sicca.