PMC6121752_01
Preoperative slit-lamp photographs.. Notes: (A) Slit-lamp photograph of the right eye before surgery. A milky white mass on the tip of the keratoconic cornea was observed. (B) Slit-lamp photograph of the patient's fellow eye. The keratoconic cornea was observed, and linear opacity under the epithelium was noted instead of a milky white mass.
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Slit-lamp examination revealed a milky white soft mass on the top of the keratoconic cornea (Figure 1A). Instead, slit-lamp examination revealed that the fellow cornea showed a linear subepithelial opacity, which was speculated to be an early stage of SCA (Figure 1B).
Congo red staining of the excised cornea.. Notes: (A) A positive stained mass was observed in the stroma connected to the inferior peripheral side of the cornea. (B) Inlet showing an enlarged view of the noted area (red arrow). The corneal stroma was normal, and no remarkable pathogenic appearance was observed in the superior peripheral corneal stroma. (C) Inlet showing an enlarged view of the noted area. The Congo red-positive mass resulted in staining in the upper half of the corneal stroma.
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Figure 2A shows the results of Congo red staining of the excised cornea. Although the superior peripheral stroma did not show any marked changes (Figure 2B), Congo red staining was detected in the central and inferior peripheral stroma (Figure 2C), near the limbus. Although the superior peripheral stroma did not show any abnormal staining (Figure 3B), irregularity was observed in the center of the cornea (Figure 3C), in the same region where the amyloid was detected by Congo red staining (Figure 2).
Hemotoxylin and eosin staining of the excised cornea.. Notes: (A) Irregularity of the collagen fibers was observed in the center of the cornea, in contrast to the regular alignment observed in the superior peripheral cornea. (B) Inlet showing an enlarged view of the peripheral cornea. (C) Inlet showing an enlarged view of the center of the cornea.
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Figure 3A shows the results of H&E staining of the collagen fibers in the cornea. Although the superior peripheral stroma did not show any abnormal staining (Figure 3B), irregularity was observed in the center of the cornea (Figure 3C), in the same region where the amyloid was detected by Congo red staining (Figure 2). The staining was not uniform and was negative in various places in the peripheral cornea (Figure 5B, arrows) where H&E staining showed no marked changes (Figure 3B).
Comparison of staining by Congo red, anti-lactoferrin antibody, and anti-TGFBIp antibody.. Notes: (A, B) The eosinophilic material was positively stained with Congo red. (C, D) The eosinophilic material was also positively stained with anti-lactoferrin antibody in an area almost overlapping the Congo red-positive region. (E, F). The complete corneal stroma was positively stained by anti-TGFBIp antibody, including the Congo red-negative (arrow) as well as the Congo red-positive area.
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Figure 4 shows the results of Congo red (Figure 4A, B), anti-lactoferrin antibody (Figure 4C, D), and anti-TGFBIp antibody (Figure 4E, F) staining. The eosinophilic material was positively stained with Congo red (Figure 4A, B). The eosinophilic material also showed a positive reaction with the anti-lactoferrin antibody (Figure 4C, D) in almost the same area as that stained positively by Congo red. Although staining with anti-TGFBIp antibody was stronger within the Congo red-positive stromal region, this staining was also confirmed within the Congo red-negative region (Figure 4F, arrow).
Masson's trichrome staining of the excised cornea.. Notes: (A) The excised cornea showed irregular collagen staining (collagen is stained blue). (B) An enlarged view of the superior peripheral cornea. (C) Higher magnification image of the central cornea. The staining was not uniform throughout the cornea and was negative at certain places within the peripheral cornea (B, arrows) as well as in the central cornea (C, arrows).
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Masson's trichrome staining (Figure 5A) showed irregular staining in the central stroma. The staining was not uniform and was negative in various places in the peripheral cornea (Figure 5B, arrows) where H&E staining showed no marked changes (Figure 3B). The staining was irregular even in the non-amyloid region (Figure 5C, arrows).
Masson's trichrome staining of the Bowman's layer.. Notes: (A) Staining of the excised cornea. (B-D) An enlarged view of each respective inlet. These inlets provide examples of (B) thinning (arrows), (C) cuts (arrow), and (D) complete disappearance (arrow). (E) An image of a normal corneal region for comparison. An arrow indicates Bowman's layer.
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Bowman's layer, which consists of type IV collagen, was also affected by the keratoconus (Figure 6A). These changes included attenuation (Figure 6B), as well as interruption (Figure 6C) and complete disappearance (Figure 6D), when compared to the normal cornea (Figure 6E).