Matthew Giegengack

Oral Mucosal Graft With Amniotic Membrane Transplantation for Total Limbal Stem Cell Deficiency

PURPOSE To report the results of oral mucosal graft for reconstruction of corneas with total limbal stem cell deficiency. DESIGN Retrospective, interventional case series. METHODS Seven patients (7 eyes) with total limbal stem cell deficiency caused by chemical burn (4 eyes), Stevens-Johnson syndrome / toxic epidermal necrolysis (1 eye), ocular cicatricial pemphigoid (1 eye), and multiple cryotherapies and application of mitomycin C for conjunctival melanoma (1 eye) were enrolled in this study. Oral mucosal graft was transplanted as a surrogate limbus together with amniotic membrane transplantation with a follow-up of at least 8 months. Symptomatic relief, restoration of a stable epithelium, corneal clarity, and the best-corrected visual acuity were assessed. RESULTS Limbal stem cell deficiency was confirmed by impression cytology in all eyes, among which 6 were bilateral while 1 was unilateral. All 7 patients presented with severe loss of vision, photophobia, pain, chronic inflammation, and corneal vascularization and scarring. For 30 ± 19.8 months, pain and photophobia were resolved in all 7 eyes; 6 eyes exhibited a stable epithelium with regressed corneal vascularization and reduced chronic inflammation. Visual acuity was improved in all 7 eyes. One eye developed partial limbal stem cell deficiency due to exposure at 47 months follow-up and was reoperated. Five eyes had peripheral corneal vascularization. CONCLUSIONS Oral mucosal graft is a viable alternative for treating total limbal stem cell deficiency in eyes where transplantation of allogeneic limbal stem cells has failed or is not feasible.

Histologic evidence of retained fetal layer of the descemet membrane after presumed total removal for endothelial keratoplasty: a possible cause for graft failure.

Purpose: This is, to our knowledge, the first report of histology after failed Descemet-stripping endothelial keratoplasty (DSEK) surgery in a patient. We describe the interface histology found in a case of donor nonadherence and subsequent graft failure in a patient after DSEK. Methods: An 83-year-old woman with a history of Fuchs dystrophy underwent DSEK surgery and subsequently underwent full-thickness penetrating keratoplasty (PKP) because of nonadherence of the donor disc and presumed graft failure. Specimens from the initial stripping of the Descemet membrane, the failed donor disc, and the full thickness of the patients remaining cornea containing the recipient bed after her DSEK and PKP procedures were histologically evaluated by light microscopy. Results: Microscopic examination of the initial stripped recipient Descemet membrane revealed a “delamination” of the Descemet membrane involving the fetal layer. After PKP, histopathologic study of the recipient button revealed residual fetal Descemet membrane retained on the recipient DSEK interface. Examination of the failed donor disc showed healthy tissue. Conclusions: In DSEK surgery, there are multiple reasons that the donor graft button may fail to adhere to the recipient posterior corneal surface. In this instance, histologic study revealed that the Descemet membrane was split by the stripping, and the fetal layer of the Descemet membrane was retained on the central part of the patients posterior cornea. Despite histologically normal donor endothelial cells, the inability of the donor tissue to adhere may have been caused by the coating of the central recipient bed with retained fetal Descemet membrane.

Factors affecting successful isolation of human corneal endothelial cells for clinical use.

Corneal transplantation is a common transplant procedure used to improve visual acuity by replacing the opaque or distorted host tissue with clear healthy donor tissue. However, its clinical utility is limited due to a lack of donor supply of high-quality corneas. Bioengineered neocorneas, created using an expandable population of human donor-derived corneal endothelial cells (HCECs), could address this shortage. Thus, the objective of this study was to evaluate HCEC sourcing with various isolation methods, including enzymatic digestion, culture medium components, and adhesive proteins. HCECs were obtained from corneas obtained from various aged donors after endothelial keratoplasty. Under a dissection microscope, the Descemets membrane, including the attached corneal endothelium, was stripped from the stroma, and the cells were isolated and expanded by explant culture or by enzymatic digestion with enzymes such as collagenase II, dispase, or trypsin. In order to improve the initial cell attachment, tissue culture plates were coated with collagen IV, fibronectin, or fibronectin–collagen combination coating mix (FNC) before cell plating. We were able to successfully obtain HCECs from 32% (86/269) of donor corneas. Donor age and isolation method influenced the characteristics of the resulting in vitro HCEC culture. Under all conditions tested, FNC-coated plates showed higher quality cultures than the other coatings tested. These results suggest that donor age and HCEC isolation methodology are the two factors that most directly affect the quality of the resulting HCEC culture in vitro. These factors should guide the methodological development for the clinical expansion of HCECs for the generation of bioengineered neocorneas.

Surgical Reduction of Dysesthetic Blebs

Dysesthetic blebs can complicate filtration surgery. Lubrication often reduces symptoms; however, some cases require surgical intervention. Limited conjunctivoplasty reduces the symptoms of dysesthetic blebs without sacrificing control of intraocular pressure (IOP). However, this may not sufficiently lower these blebs, particularly if the bleb is thick and dense. We describe a modified conjunctivoplasty technique that includes removal of subconjunctival scar tissue within the interpalpebral fissure and provide a 1-year follow-up of 13 eyes treated in this manner. All patients reported rapid, complete symptom resolution. The IOP was controlled in all 13 eyes following conjunctivoplasty; 3 required topical antiglaucoma therapy. Subconjunctival scar tissue may contribute to the formation of dysesthetic blebs owing to its thickness and by encouraging local dissection of aqueous humor. Our report demonstrates that removal of this tissue does not compromise IOP control when performed with conjunctivoplasty.

Constructing the cornea: hopes and challenges for regenerative medicine

The need for alternatives to cadaveric cornea transplant The first corneal transplant was performed in 1905. Since then corneal transplant surgery has improved greatly. In the past decade, advances in lamellar keratoplasty have made it possible to transplant post erior corneas for corneal endothelial disease or anterior corneas for stromal disease. Limbal stem cell grafts are used for corneal epithelial disease. With improvements in technique come increases in the demand for corneal tissue as more conditions are readily treatable. The WHO estimates that 4.9 million people worldwide suffer from corneal blindness. This number is staggering, even before we consider the estimates for people who are merely visually impaired in one or both eyes due to corneal disease. Currently, the USA (population 313 million) has the most extensive eye banking system of the developed world. The Eye Bank Association of America keeps detailed records of transplants performed annually. In 2011, 46,196 corneal transplants were performed [1]. If a similar rate of transplants were performed worldwide (population seven billion), approximately 1,000,000 transplants would be performed annually. Based on those numbers, it is apparent that there is a worldwide need for donor corneal tissue. There is room for improvement in the USA as well. For those 46,196 corneal transplants that were performed, 114,348 corneas were donated and 18,307 of these corneas were exported internationally. A total of 29,407 corneas were disqualified because they did not meet standards [1]. The leading reasons for disqualification included poor tissue quality on slit lamp exam, positive serology for communicable diseases and medical record or autopsy findings. While the USA sets the standards very high for donor tissue, there is a range of quality of the tissue that meets these standards. Age parameters of acceptability are set, but it is generally believed that younger tissue is preferable. Minimum endothelial cell counts on donor tissue is set, but more is better. Death to preservation time of donor tissue is best when short. The list goes on. Many potential donor corneas are rejected due to positive serology for communicable diseases. Even with testing, the possibility of disease transmission through transplantation remains. Currently not all communicable diseases are testable. Additionally, with these standards comes significant cost. In the USA, the average cost of harvesting, clearing and supplying a cornea for penetrating keratoplasty is roughly US

Heparin-modified gelatin scaffolds for human corneal endothelial cell transplantation.

3000. Preparing corneas for endothelial keratoplasty has additional steps and consequently adds US

In vitro evaluation of the interactions between human corneal endothelial cells and extracellular matrix proteins

1000–1500 to the cost. As the numbers of transplants continue to increase, the annual healthcare costs become increasingly significant. The data are compelling for the need of a substitute for the traditional donor cornea. Worldwide, the lack of donor tissue relative to corneal disease is staggering. In Constructing the cornea: hopes and challenges for regenerative medicine