Donor Descemet Membrane Research Articles

Multirecurrence of Corneal Posterior Polymorphous Dystrophy

Posterior polymorphous corneal dystrophy (PPD) is a rare bilateral, autosomal-dominant disease. The presence of the epitheliumlike endothelium and the thickening of Descemet's membrane by the posterior collagenous layer (PCL) has been reported in the majority of published cases. Reepithelialization of the posterior cornea in donor tissue has been reported only once. Therefore, to examine this process we examined, by light and electron microscopy, three corneal buttons (an original and two subsequent keratoplasties after 3 and 4 years, respectively) from the left eye of a patient with bilateral disease. Our study showed a repopulation of the posterior surface of the donor corneas by the host epitheliumlike endothelium, which was of identical morphology in each case. In contrast to the previously published work, a posterior collagenous layer in the failed grafts was absent from the axial cornea, where the epitheliumlike endothelium was in direct contact with donor Descemet's membrane. A PCL at the periphery in the failed transplants was of the fibrocellular type and differed from the fibrillar PCL in the first keratoplasty specimen. The fibroblastlike cells within the fibrocellular PCL were distinct from the underlying epithelial-like cells and contained numerous tertiary phagolysosomes. We suggest that the major contributor to the fibrocellular PCL in the repeat keratoplasties was a fibrous ingrowth from the host/graft junction and not the epitheliumlike endothelium. It appears that the synthetic capacity of the epitheliumlike endothelium was similar to that of the normal epithelium and was much lower than that of normal native endothelium.

Corneal endothelial cell transplantation using Descemet's membrane as a carrier

Rabbit corneal endothelial cells were transplanted into the right eyes of four New Zealand white rabbits using bovine Descemet's membrane as a cell carrier. Descemet's membranes were dissected from cow eyes, flattened on 36 mm culture dishes, and cut into discs with a 6 mm trephine. Rabbit corneal endothelial cells were seeded onto the discs and maintained in tissue culture conditions for seven days until a complete monolayer with a cell density of 3,000 cells/mm2 was formed. Before transplantation, corneal edema was induced in the host animals by an endothelial scrape wound, which removed the corneal endothelium. Five weeks later, the animals were prepared for transplantation. A corneal button was cut and placed on a dissection table so the host Descemet's membrane could be removed. The donor Descemet's membrane with a complete monolayer of rabbit corneal endothelial cells was placed on the stroma of the corneal button. To keep the donor membrane in place, the button was cauterized at three peripheral points and sutured back into the host eye. Prednisolone sodium phosphate eyedrops and dexamethasone eyedrops and ointment were applied twice daily during the postoperative period. All grafts stayed clear for a period of 12 to 17 weeks. This study shows the potential for using Descemet's membrane as a carrier for corneal endothelial cell transplantation.

Full-Thickness Lamellar Keratoplasty: A Histologic Study in Human Eyes

Four human eyes, obtained 38 days to 5 years after fullthickness lamellar keratoplasty, were studied by light microscopy for evidence of fibroblast proliferation and collagen formation between the donor Descemet's membrane and the recipient stromal bed. There was delayed healing in the membrane to stroma interface, but at the graft margins a relatively normal stroma-to-stroma healing response was evident. Even in the five-year specimen, bridging of recipient collagen to donor Descemet's membrane was noted only where it was associated with subgraft vascularization. All donor endothelium had disappeared. These studies indicate that in human eyes, retention of Descemet's membrane results in a weaker total graft-host bond than provided by conventional lamellar keratoplasty. In addition, this altered healing may predispose to pseudoanterior chambers that may decrease visual acuity and diminish the theoretical optical advantages of a smooth Descemet's membrane in the graft host interface.