Intrastromal corneal rings were approved by the US Food and Drug Administration in 1999 for the correction of a low degree of myopia. 1, 2 The parameters influencing the final surgery outcome are the diameter and thickness of these intrastromal corneal segments. INTACS involves the insertion of 2 semicircular plastic segments into the corneal stroma, thereby creating central flattening and correcting small amounts of myopia. Patterns of type IV collagen α3, α4, and α6 chains types VI and VIII collagen laminin-332,α4, α5,β1, β2, and γ1 laminin chains vitronectin thrombospondin-1 urokinase EMMPRIN and cathepsins B and L were unchanged around INTACS in all 3 cases compared with normal. Staining for MMP-7 was variable MMP-2 and MMP-9 were mostly negative. In all cases, some keratocytes around INTACS were positive for specific proteinases associated with stromal remodeling, including cathepsins F and H, matrix metalloproteinase (MMP)-1, MMP-3, and MMP-10. The keratoconus cases displayed typical Bowman layer breaks and subepithelial fibrosis with deposition of various ECM components. Also, significant deposition of perlecan, nidogen-2, and cellular fibronectin was revealed in the same locations. These included tenascin-C, fibrillin-1, and types III, IV (α1/α2 chains), and XIV collagen. In the stroma of all corneas next to an INTACS implant, ECM components typically associated with fibrosis were observed.
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