(A1 & A2) Clinical photographs of oGVHD patients showing translucent and whitish MCAs on the ocular surface (arrows). (A3) Hematoxylin and Eosin (H&E) staining of MCA shows numerous neutrophils, surface epithelial cells and extracellular DNA strands. (B1-B4) Confocal immunofluorescent staining of MCA showing co-localization of neutrophil elastase (NE) (B1, red), Citrulline H3 (B2, citH3, green) and DAPI nuclear staining (B3, blue) in extracellular strands (B4, arrows) confirming that these extracellular strands are NETs. Confocal immunofluorescent staining of MCA showing co-localization of NE (C1, red), myeloperoxidase (C2, green) and DAPI nuclear stain (C3, blue) in extracellular strands (C4, white arrows) further confirming that these extracellular strands are NETs. (D1-E4): Analysis of a MCA adhered to the cornea of an oGVHD patient. (D1) Clinical photograph of an oGVHD patient showing MCAs adhered to the cornea. (D2) Clinical photograph of the same patient after application of a filter paper to the cornea to lift the MCA. (D3) H&E staining of the filter paper shows that MCA comprises of neutrophils, surface epithelial cells and extracellular DNA strands. (E1-E4) Confocal immunofluorescent staining of the MCA shows co-localization of citH3 (E1, red), NE (E2, green) and DAPI nuclear staining (E3, blue) in extracellular strands (E4, white arrows) confirming that these extracellular strands within the MCA are NETs.