Corneal Graft Failure
Corneal graft failure typically results from significant loss of endothelial cells in grafted donor corneal tissue (Fig 6-14). It is one of the most common indications for PK or endothelial keratoplasty (EK). Graft failure after PK or EK may occur within a few weeks of surgery (primary graft failure), gradually over time, or following an acute rejection episode. Wound-related complications, such as fibrous or epithelial ingrowth or downgrowth, can also contribute to graft failure and are most common with PK grafts (see Fig 6-14E, F). The final common pathway is endothelial cell loss. When endothelial failure occurs, associated bullous keratopathy often develops. A delicate, fibrous retrocorneal membrane (fibrous downgrowth) may be seen, and there is a paucity or absence of endothelial cells. For various types of EK, additional important etiologies of graft failure include traumatic intracameral insertion of donor tissue, loss of adherence of the donor lenticule to the posterior stroma, and prolonged presence of the air bubble in the anterior chamber. See also BCSC Section 8, External Disease and Cornea.
Figure 6-14 Corneal graft failure. A, PAS stain of a failed penetrating keratoplasty (PK) graft with diffuse endothelial cell loss; fibrous retrocorneal membrane (F); stromal edema with bullous keratopathy (arrowhead) and absence of stromal clefts; epithelial basement membrane thickening (arrow); and focal fibrous pannus (asterisk). B, Clinical photograph illustrating fibrous downgrowth (arrows).C, PAS stain of a failed graft following endothelial keratoplasty (EK). The donor lenticule is positioned upside down (L) with donor Descemet membrane (arrowheads) facing recipient Descemet membrane (arrows). Note the endothelial attenuation and marked stromal edema. D, PAS stain of a failed EK donor lenticule. Note the total absence of endothelium (arrows). E, Clinical photograph showing epithelial downgrowth (arrowheads) in a PK graft. F, Histology of a cornea from PK following failed EK shows full-thickness cornea with Bowman layer (black arrowheads) on the right and partial-thickness cornea on the left. The surface epithelium is discontinuous (arrow). A layer of squamous epithelium (epithelial ingrowth) (red arrowheads) replaces endothelial cells.
(Part A courtesy of George J. Harocopos, MD; parts B and F courtesy of Anthony J. Lubniewski, MD; parts C and E courtesy of Tatyana Milman, MD; part D courtesy of Hans E. Grossniklaus, MD.)
Figure 6-15 Corneal blood staining. A, Clinical photograph. Note the rust-colored opacity of the central cornea. B, Masson trichrome stain. The red particles represent erythrocytic debris and hemoglobin in the corneal stroma. C, An iron stain (blue staining) demonstrates hemosiderin (arrows) within stromal keratocytes.
(Part A courtesy of Anthony J. Lubniewski, MD; parts B and C courtesy of Hans E. Grossniklaus, MD.)
Excerpted from BCSC 2020-2021 series: Section 4 - Ophthalmic Pathology and Intraocular Tumors. For more information and to purchase the entire series, please visit https://www.aao.org/bcsc.