Comparison of rebubbling rate between preloaded endothelium-in and preloaded no-touch endothelium-out Descemet membrane endothelial keratoplasty transplantation.

BACKGROUND: To compare the difference in rebubbling rates between patients undergoing Descemet membrane endothelial keratoplasty (DMEK) with endothelium-in using a standard IOL cartridge and those with endothelium-out DMEK utilizing a no-touch technique with borosilicate glass cartridge transplantation. METHODS: This retrospective study included all eyes that underwent preloaded endothelium-in or endothelium-out DMEK transplantation from June 2019 to December 2023 at the Hanusch Hospital, Vienna, Austria. All DMEKs were harvested, prepared and preloaded at the European Eye Bank of Venice, Italy. DMEK surgeries were done by one experienced surgeon and the procedure was completed by air tamponade of the anterior chamber. RESULTS: Overall, 32 eyes each of 31 endothelium-out patients and of 29 endothelium-in patients were included. 32 preloaded endothelium-in procedures were followed by 32 preloaded endothelium-out procedures. Rebubbling rate for endothelium-in was 15/32 (47%) and for endothelium-out was 7/25 (28%) (p = 0.035, Pearson's chi-squared test). Donor age was the most important variable for rebubbling in a random forest algorithm model (ROC: 0.69). CONCLUSIONS: Rebubbling rate in endothelium-out DMEK was less than two-thirds compared to endothelium-in DMEK favoring no-touch endothelium-out DMEK as the preferred technique of DMEK transplantation.

Cost Drivers of Endothelial Keratoplasty: A Time-Driven Activity-Based Costing Analysis.

PURPOSE: To determine cost drivers of endothelial keratoplasty (EK) through evaluation of surgical costs and procedure length based on type of EK, use of preloaded grafts, and performance of simultaneous cataract surgery. DESIGN: This study was an economic analysis of EKs at a single academic institution using time-driven activity-based costing (TDABC) methodology. PARTICIPANTS: Endothelial keratoplasty surgical cases, including Descemet membrane endothelial keratoplasty (DMEK) and Descemet stripping automated endothelial keratoplasty (DSAEK), at the University of Michigan Kellogg Eye Center from 2016 to 2018 were included in the analysis. METHODS: Data and inputs were obtained via the electronic health record (EHR) and from prior literature. Simultaneous cataract surgeries were included and separately categorized for analysis. Endothelial keratoplasty expenses were determined with TDABC, a method for cost calculation that incorporates the time that key resources are used and each resource's associated cost rate. MAIN OUTCOME MEASURES: Main outcome measures included surgery length (in minutes) and day-of-surgery costs. RESULTS: There were 559 EKs included: 355 DMEKs and 204 DSAEKs. Fewer DSAEKs had simultaneous cataract extraction (47; 23%) than DMEK (169; 48%). Of the DMEKs, 196 (55%) used preloaded corneal grafts. Descemet membrane endothelial keratoplasty cost $392.31 less (95% confidence interval, $251.05-$533.57; P < 0.0001) than DSAEK and required 16.94 fewer minutes (14.16-19.73; P < 0.0001). Descemet membrane endothelial keratoplasty cases that used preloaded corneal grafts cost $460.19 less ($316.23-$604.14; P < 0.0001) and were 14.16 minutes shorter (11.39-16.93; P < 0.0001). In multivariate regression, preloaded graft use saved $457.19, DMEK (compared with DSAEK) saved $349.97, and simultaneous cataract surgery added $855.17 in day-of-surgery costs. CONCLUSIONS: Cost analysis of TDABC identified a day-of-surgery cost and surgical time reduction associated with the use of preloaded grafts for DMEK, DMEK compared with DSAEK, and isolated EK compared with EK combined with cataract surgery. This study provides an improved understanding of surgical cost drivers and margin incentivization, which may explain trends and indirectly influence patient care decisions in cornea surgery practices. FINANCIAL DISCLOSURE(S): Proprietary or commercial disclosure may be found in the Footnotes and Disclosures at the end of this article.

The usefulness of lutein/trypan blue vital dye for the staining of corneal endothelium: a pilot study on DMEK pretreated tissues.

PURPOSE: The study aims to evaluate the usefulness of lutein/trypan blue vital dye for the staining of corneal tissues and endothelium-Descemet membrane (EDM) for Descemet membrane endothelial keratoplasty (DMEK). METHODS: Sixteen human corneal tissues (Eye Bank, Rome, Italy) were used. Corneal endothelium was tested at 25 s (T0), 1 min (T1), 2 min (T2), and 4 min (T4) from dye addition. Staining intensity and cell counting were compared. Stripped EDM was analyzed for selected apoptotic (AP, caspases, BCL2, BAX) and differentiation (VEGF-A, TGF-ß1RI, SMAD3/7, SMA) targets and changes in target expression. Protein extracts were analyzed through SDS-PAGE/IB. RESULTS: Although trypan blue staining produced the same color intensity of lutein/trypan blue dye in half the time, lutein/trypan blue reached a good and adequate color intensity at T4, which persisted even on excised and washed EDM grafts. Lutein/trypan blue-stained EDM showed a reduced number of blue-stained cells and AP immunoreactivity was significantly reduced in the same samples. An increased BCL2 transcript and a reduced BAX transcript were detected in lutein/trypan blue-stained EDM. No significant changes were observed for the main effector caspases (3/9) upon both treatments and the target genes representative of endothelial cell trans-differentiation (TGF-ß1RI, SMAD3/7, SMA). A trend in vascular endothelial growth factor (VEGF-A) regulation was observed in lutein/trypan blue-treated EDM grafts. CONCLUSION: Obtained results suggest that lutein/trypan blue dye deserves attention in the DMEK field and support the potential routine use of this dye as a valid alternative to trypan blue for all procedures devoted to the assessment of endothelial cell viability and visualization of EDM graft before DMEK grafting.

Descemet Membrane Endothelial Keratoplasty in Combination with Pars Plana Vitrectomy in Complex Eyes for Enhanced Gas Tamponades. / Descemet-Membran-Endothel-Keratoplastik in Kombination mit Pars-plana-Vitrektomie in komplexen Augen zur extensiven Gastamponade.

BACKGROUND: DMEK is well-established to treat endothelial corneal diseases. The procedure involves the use of an anterior chamber gastamponade to attach the graft. In eyes after lense extraction, fistulating glaucoma surgery or with large iris defects the gas tamponade is often lost postoperatively in the vitreous cavity or subconjunctival. We are reporting on three cases below, in which simultaneous anterior and posterior chamber gas tamponade were inserted with a combination of DMEK and 23-G pars plana vitrectomy (ppV). CASE DESCRIPTIONS: In the first case, a 70-year-old man experienced complete gas dislocation into the vitreous cavity early on after DMEK, resulting in re-bubbling being carried out in combination with 23-G ppV. In the second case, DMEK was immediately combined with ppV for an 80-year-old man who had an Ahmed glaucoma implant, and for a 61-year-old woman, our third case, who had traumatic aphakia. In all three cases, the vitreous cavity and anterior chamber were filled with 20% SF 6 as much as possible. In the second case, it was necessary to perform a re-bubbling due to partial graft dehiscence that occurred on the fifth day post-DMEK. The intraocular pressure in all three cases remained compensated postoperatively, and visual acuity increased despite the complex pre-existing conditions that had limited vision prior. DISCUSSION: The combined endotamponade of the anterior and posterior chambers while performing DMEK with 23-G ppV can extend the gas endotamponade in patients whose eyes have a complex medical history, and can thus ensure successful graft adherence.

Descemet membrane endothelial keratoplasty in complex eyes.

PURPOSE OF REVIEW: To review the current literature on Descemet membrane endothelial keratoplasty (DMEK) in complex eyes. RECENT FINDINGS: DMEK surgery has become a standardized procedure in Fuchs endothelial dystrophy and simple bullous keratopathy. But eyes with more complex disease present unique intraoperative and postoperative challenges to the DMEK surgeon. Poor visualization during surgery, complex anterior segment anatomy, altered anterior chamber dynamics, glaucoma shunts, and congenital or iatrogenic missing or altered iris and lens make DMEK surgery extremely difficult to accomplish. SUMMARY: DMEK is feasible in complex eyes, including advanced bullous keratopathy, eyes with history of glaucoma or vitreoretinal surgery, previous penetrating keratoplasty, uveitis, pediatric, and congenital anterior segment disorders. The tools and methods reported in the literature to accomplish DMEK in complex eyes vary widely with no particular consensus or standardization of techniques. The outcomes noted for some of these conditions demonstrate the difficulty of the surgery and the uncertainty of long-term graft survival in complex eyes. Both surgical standardization and randomized prospective data will better help elucidate DMEK's role in the corneal rehabilitation of complex eyes.

Graft survival of Descemet membrane endothelial keratoplasty (DMEK) in corneal endothelial decompensation after glaucoma surgery.

PURPOSE: This study aims to assess the results, rebubbling rate, and graft survival after Descemet membrane endothelial keratoplasty (DMEK) with regard to the number and type of previous glaucoma surgeries. METHODS: This is a clinical retrospective review of 1845 consecutive DMEK surgeries between 07/2011 and 08/2017 at the Department of Ophthalmology, University of Cologne. Sixty-six eyes were included: group 1 (eyes with previous glaucoma drainage devices (GDD); n = 27) and group 2 (eyes with previous trabeculectomy (TE); n = 39). Endothelial cell loss (ECL), central corneal thickness, graft failure, rebubbling rate, and best spectacle-corrected visual acuity (BSCVA) up to 3 years after DMEK were compared between subgroups of patients with different numbers of and the two most common types of glaucoma surgeries either GDD or TE or both. RESULTS: Re-DMEK rate due to secondary graft failure was 55.6% (15/27) in group 1 and 35.9% in group 2. The mean graft survival time in group 1 was 25 ± 11 months and 31.3 ± 8.6 months in group 2 (p = 0.009). ECL in surviving grafts in group 1 was 35% (n = 13) at 6 months, 36% at 12 months (n = 8), and 27% (n = 4) at 2 years postoperatively. In group 2, ECL in surviving grafts was 41% (n = 10) at 6 months, 36% (n = 9) at 12 months, and 38% (n = 8) at 2 years postoperatively. Rebubbling rate in group 1 was 18.5% (5/27) and 35.9% (14/39) in group 2 (p = 0.079). CONCLUSION: Eyes with previous GDD had no higher risk for an increased rebubbling rate but a higher risk for a re-DMEK due to secondary graft failure with a mean transplant survival time of about 2 years. Compared to eyes with preexisting glaucoma drainage device, eyes after trabeculectomy had less secondary graft failures and a longer mean graft survival rate.

In vitro infection of human ocular tissues by SARS-CoV-2 lineage A isolates.

BACKGROUND: The purpose of this study was: [1] to evaluate the infectivity of two SARS-CoV-2 lineage A variants on human ocular tissues in vitro, and [2] to evaluate the stability of SARS-CoV-2 lineage A variants in corneal preservation medium. METHODS: Primary cultures of donor corneal, conjunctival, and limbal epithelium were inoculated with two lineage A, GISAID clade S isolates of SARS-CoV-2 (Hong Kong/VM20001061/2020, USA-WA1/2020), to evaluate the susceptibility of the ocular tissue to infection. Flat-mounted Descemet's Stripping Automated Endothelial Keratoplasty (DSAEK) grafts were inoculated with SARS-CoV-2 to evaluate the susceptibility of the endothelium to infection. All inoculated samples were immunostained for SARS-CoV-2 nucleocapsid (N)-protein expression to confirm positive infection. SARS-CoV-2 Hong Kong was then inoculated into cornea preservation media (Life4°C, Numedis, Inc.). Inoculated media was stored at 4oC for 14 days and assayed over time for changes in infectious viral titers. RESULTS: Corneal, conjunctival, and limbal epithelial cells all demonstrated susceptibility to infection by SARS-CoV-2 lineage A variants. Conjunctiva demonstrated the highest infection rate (78% of samples infected [14/18]); however, infection rates did not differ statistically between cell types and viral isolates. After inoculation, 40% (4/10) of DSAEK grafts had active infection in the endothelium. SARS-CoV-2 lineage A demonstrated < 1 log decline in viral titers out to 14 days in corneal preservation media. CONCLUSIONS: SARS-CoV-2 lineage A variants can infect corneal, limbal, and conjunctival epithelium, as well as corneal endothelium. There was no statistical difference in infectivity between different lineage A variants. SARS-CoV-2 lineage A can survive and remain infectious in corneal preservation media out to 14 days in cold storage.

Effects of Systemic Diseases on Graft Preparation in Descemet Membrane Endothelial Keratoplasty.

OBJECTIVES: To evaluate the effects of the systemic diseases and drugs of the donor on Descemet membrane (DM) graft preparation. METHODS: Seventy-eight corneas of 58 donors, of whom the DM grafts were used in Descemet membrane endothelial keratoplasty (DMEK) surgery, between January 2018 and January 2020, were enrolled in this retrospective study. The hospital records of the donors were analyzed. Age, sex, blood type, systemic diseases, and drugs; complete blood count; biochemistry panel for liver and kidney functions in the past 48 hours; and the drugs used in the hospital, if any, in the past 24 hours were recorded. The grafts with tears that occurred while preparation were included in group 1, and the successful grafts with no tears were included in group 2. RESULTS: There were no statistically significant differences in the characteristics of the donors between groups. However, breast cancer and the use of sevelamer were found to be significantly higher in group 1 ( P =0.010, P =0.033, respectively). No statistically significant difference in the use of other drugs was found between groups. CONCLUSION: Although diabetic donors have been reported to be inappropriate candidates for the preparation of DM grafts for DMEK, most of the donors with several systemic diseases including diabetes can be used in DMEK surgery, with the right technique in DM graft preparation.

Severe Corneal Edema Increases ECL From Grafts After DSAEK-Corneal Edema and ECL After DSAEK.

OBJECTIVES: To determine the relationship between the preoperative degree of corneal edema in the recipient and the endothelial cell density in grafts after Descemet stripping automated endothelial keratoplasty (DSAEK). METHODS: This retrospective case series enrolled 111 eyes of 107 patients who underwent DSAEK. The preoperative and postoperative central corneal thickness (CCT) was measured by anterior-segment optical coherence tomography. Eyes were divided into three groups according to the preoperative recipient CCT: group A (mild edema): 550 µm

Nomogram for single-pass automated microkeratome graft preparation for ultrathin Descemet stripping automated endothelial keratoplasty.

PURPOSE: To create a nomogram including the translational speed of the microkeratome blade, microkeratome head size and precut tissue thickness to predict the postcut thickness for Descemet stripping automated endothelial keratoplasty to obtain the thinnest possible graft. METHODS: This prospective study incorporated 48 grafts for DSAEK from March 2017 to June 2020. Corneal tissue for DSAEK was prepared by 3 experienced physicians using the Moria Evolution 3E (Moria Inc, Antony, France) microkeratome with 400, 450 and 500 µm head sizes. Precut central corneal thickness was measured with a DGH 550 handheld pachymeter (Pachette 2), taking an average of 3 readings. The microkeratome head was selected according to precut tissue thickness. The selected microkeratome head size was 150 µm less than the donor cornea thickness. Two translational speeds were used for the microkeratome cuts. One month after surgery, the central lenticular thickness was measured with a Visante® Optical Coherence Tomography caliper (Carl Zeiss Meditec Inc, Germany). A descriptive analysis was performed. RESULTS: Forty-eight donor grafts were prepared. Mean graft thickness was 97.58 ± 29.84 µm (range 39-176 µm). Of the 48 samples, central graft thickness was < 120 µm (81.3%) in 39, < 100 µm (58.3%) in 28 and < 80 µm (37.5%) in 18 at 1-month follow-up. There were no statically significant differences between translational speeds. CONCLUSIONS: A nomogram with an automated microkeratome to obtain thin grafts for DSAEK provided good graft thickness results without donor waste.

[On the issue of allocating the pre-Descemet's layer in the corneal structure]. / K voprosu o vydelenii predestsemetovogo sloya v strukture rogovitsy.

Selective keratoplasty is known to be based on surgical manipulations aimed at dosed isolation of layered grafts in the corneas of the donor and the recipient. Some technological features of obtaining transplants have served as the basis for expanding the understanding of the corneal structure. Thus, analysis of the process of corneal stroma pneumodissection for isolation of the Descemet's membrane led to a suggestion that there was another layer in the cornea, it was designated as the pre-Descemet's layer. This article discusses the practicability of separating the pre-Descemet's layer from the perspective of structural, functional and surgical anatomy.

Five-Year Follow-up of First 11 Patients Undergoing Injection of Cultured Corneal Endothelial Cells for Corneal Endothelial Failure.

PURPOSE: To report the safety and efficacy of a novel cell injection therapy using cultured human corneal endothelial cells (hCECs) for endothelial failure conditions via the report of the long-term 5-year postoperative clinical data from a first-in-humans clinical trial group. DESIGN: Prospective observational study. PARTICIPANTS: This study involved 11 eyes of 11 patients with pseudophakic endothelial failure conditions who underwent hCEC injection therapy between December 2013 and December 2014. METHODS: All patients underwent follow-up examinations at 1 week, 4 weeks, 12 weeks, and 24 weeks and 1 year, 2 years, 3 years, 4 years, and 5 years after surgery. Specific corneal endothelial cell parameters (i.e., corneal endothelial cell density [ECD], coefficient of variation of area, and percentage of hexagonal cells) and central corneal thickness, best-corrected visual acuity (BCVA) on a Landolt C eye chart, and intraocular pressure (IOP) were recorded. MAIN OUTCOME MEASURES: The primary outcome was the change in central ECD after cell injection therapy, and the secondary outcome was corneal thickness, BCVA, and IOP during the 5-year-postoperative follow-up period. RESULTS: At 5 years after surgery, normal corneal endothelial function was restored in 10 of the 11 eyes, the mean ± standard deviation central corneal ECD was 1257 ± 467 cells/mm2 (range, 601-2067 cells/mm2), BCVA improved significantly in 10 treated eyes, the mean visual acuity changed from 0.876 logarithm of the minimum angle of resolution before surgery to 0.046 logarithm of the minimum angle of resolution after surgery, and no major adverse reactions directly related to the hCEC injection therapy were observed. CONCLUSIONS: The findings in this study confirmed the safety and efficacy of cultured hCEC injection therapy for up to 5 years after surgery.

Current development of alternative treatments for endothelial decompensation: Cell-based therapy.

Current treatment for corneal endothelial dysfunction consists in the replacement of corneal endothelium by keratoplasty. Owing to the scarcity of donor corneas and the increasing number of transplants, alternative treatments such as cell-based therapies are necessary. In this article, we highlight the biological aspects of the cornea and the corneal endothelium, as well as the context that surrounds the need for new alternatives to conventional keratoplasty. We then review some of those experimental treatments in more detail, focusing on the development of the in vitro and preclinical phases of two cell-based therapies: tissue-engineered endothelial keratoplasty (TE-EK) and cell injection. In the case of TE-EK graft construction, we analyse the current progress, considering all the requirements it must meet in order to be functional. Moreover, we discuss the inherent drawbacks of endothelial keratoplasties, which TE-EK grafts should overcome in order to make surgical intervention easier and to improve the outcomes of current endothelial keratoplasties. Finally, we analyse the development of preclinical trials and their limitations in terms of performing an optimal functional evaluation of cell-based therapy, and we conclude by discussing early clinical trials in humans.

Comparison of the rabbit and human corneal endothelial proteomes regarding proliferative capacity.

The shortage of human donor corneas has raised important concerns about engineering of corneal endothelial cells (CECs) for clinical use. However, due to the limited proliferative capacity of human CECs, driving them into proliferation and regeneration may be difficult. Unlike human CECs, rabbit CECs have a marked proliferative capacity. To clarify the potential reason for this difference, we analysed the proteomes of four human corneal endothelium samples and four rabbit corneal endothelium samples with quantitative label-free proteomics and downstream analysis. We discovered that vitamin and selenocompound metabolism and some signaling pathways such as NF-kappa B signaling pathway differed between the samples. Moreover, TGFß, PITX2 and keratocan were distinctively expressed in rabbit samples, which might be associated with active proliferation in rabbit CECs. This study illustrates the proteomic differences between human and rabbit CECs and might promote CEC engineering strategies.

Corneal endothelial cell density in patients receiving chemotherapy.

PURPOSE: This study aimed to determine if the corneal endothelium was affected by chemotherapy. METHODS: Chemotherapy patients were recruited to undergo specular microscopy before treatment and again at 1- and 2-year follow-up visits. One eye per patient, per follow-up, was selected for comparison to baseline. RESULTS: Forty-six volunteers completed baseline and at least one follow-up assessment. From 51 eyes, there was no significant change in endothelial cell density for 41 eyes assessed at one year (MD = 0.73%, 95% CI -1.33 to 2.78%) and 18 eyes at two years (MD = 0.31%, 95% CI -3.53 to 4.15%). CONCLUSION: Although other studies have shown that chemotherapy can adversely affect the corneal epithelium, this study showed no measurable change in endothelial cell density.

Cost-Effectiveness Analysis of Descemet's Membrane Endothelial Keratoplasty Versus Descemet's Stripping Endothelial Keratoplasty in the United States.

PURPOSE: To determine the cost-effectiveness of Descemet's membrane endothelial keratoplasty (DMEK) compared with Descemet's stripping automated endothelial keratoplasty (DSAEK) in the United States. DESIGN: Cost-effectiveness analysis in a surgical center in the United States. PARTICIPANTS: Binocular adult patient undergoing endothelial keratoplasty. METHODS: A base case of a 70-year-old man undergoing his first endothelial keratoplasty for bilateral Fuchs endothelial dystrophy. The cost-effectiveness of DMEK was compared with DSAEK over a 15-year time horizon. The incidences and costs of complications were derived from PubMed English literature searches, Medicare reimbursements, and average wholesale prices. All costs were discounted 3% per annum and adjusted for inflation to 2018 U.S. dollars. Uncertainty was evaluated using deterministic and probabilistic sensitivity analyses. MAIN OUTCOME MEASURES: Incremental cost-effectiveness ratios and incremental cost-utility ratios, measured in cost per quality-adjusted life-years (QALYs). RESULTS: Performing a DMEK instead of a DSAEK generated an extra 0.4 QALYs over a 15-year period. From a societal and third-party payer perspective, DMEK was cost-saving when compared with DSAEK in improving visual acuity in the base case. Probabilistic sensitivity analyses with variations in the costs and rebubble rates revealed that DMEK was cost-saving compared with DSAEK in 38% of iterations and was within a societal willingness-to-pay threshold of $50 000 in 98% of models. CONCLUSIONS: From the societal and third-party payer perspectives in the United States, DMEK generated greater utilities and was less costly than DSAEK. Therefore, DMEK was the dominant procedure and was cost-saving with respect to DSAEK. The economic model was robust based on sensitivity analyses.

Advances in culture, expansion and mechanistic studies of corneal endothelial cells: a systematic review.

Human corneal endothelial cells are notorious for their restricted proliferative ability in vivo and in vitro. Hence, injury or dysfunction of these cells may easily result in blindness. Currently, the only treatment is to transplant a donor cornea that contains a healthy corneal endothelium. However there is a severe global shortage of donor corneas and there remains an unmet clinical need to engineer human corneal grafts with healthy corneal endothelium. In this review, we present current advances in the culture, expansion, and molecular understandings of corneal endothelial cells in vitro in order to help establish methods of engineering human corneal endothelial grafts.

The future of keratoplasty: cell-based therapy, regenerative medicine, bioengineering keratoplasty, gene therapy.

PURPOSE OF REVIEW: To provide an update on the state of development of novel therapeutic modalities for the treatment of corneal diseases. RECENT FINDINGS: Novel corneal therapeutics may be broadly classified as cell therapy, regenerative medicine, bioengineered corneal grafts and gene therapy. Cell therapy encompasses cultivation of cells, such as corneal endothelial cells (CECs) and keratocytes to replenish the depleted native cell population. Regenerative medicine is mainly applicable to the corneal endothelium, and is dependent on the ability of native, healthy CECs to restore the corneal endothelium following trauma or descemetorhexis; this approach may be effective for the treatment of Peter's anomaly and Fuchs endothelial corneal dystrophy (FECD). Bioengineered corneal grafts are synthetic constructs designed to replace cadaveric corneal grafts; tissue-engineered endothelial-keratoplasty grafts and bioengineered stromal grafts have been experimented in animal models with favourable results. Gene therapy with antisense oligonucleotide and CRISPR endonucleases, including deactivated Cas9, may potentially be used to treat FECD and TGFBI-related corneal dystrophies. SUMMARY: These novel therapeutic modalities may potentially supersede keratoplasty as the standard of care in the future.

Engineering of Human Corneal Endothelial Cells In Vitro.

Human corneal endothelial cells are responsible for controlling corneal transparency, however they are notorious for their limited proliferative capability. Thus, damage to these cells may cause irreversible blindness. Currently, the only way to cure blindness caused by corneal endothelial dysfunction is via corneal transplantation of a cadaver donor cornea with healthy corneal endothelium. Due to severe shortage of donor corneas worldwide, it has become paramount to develop human corneal endothelial grafts in vitro that can subsequently be transplanted in humans. Recently, we have reported effective expansion of human corneal endothelial cells by reprogramming the cells into progenitor status through use of p120-Kaiso siRNA knockdown. This new reprogramming approach circumvents the need of using induced pluripotent stem cells or embryonic stem cells. Successful promotion of this technology will encourage scientists to re-think how "contact inhibition" can safely be perturbed to our benefit, i.e., effective engineering of an in vivo-like tissue while successful maintaining the normal phenotype. In this review, we present current advances in reprogramming corneal endothelial cells in vitro, detail the methods to successful engineer human corneal endothelial grafts, and discuss their future clinical applications to cure corneal blindness.

Corneal transplantation in the modern era.

Corneal blindness is one of the major causes of reversible blindness, which can be managed with transplantation of a healthy donor cornea. It is the most successful organ transplantation in the human body as cornea is devoid of vasculature, minimizing the risk of graft rejection. The first successful transplant was performed by Zirm, and since then, corneal transplantation has seen significant evolution. It has been possible because of the relentless efforts by researchers and the increase in knowledge about corneal anatomy, improvement in instruments and advancements in technology. Keratoplasty has come a long way since the initial surgeries wherein the whole cornea was replaced to the present day where only the selective diseased layer can be replaced. These newer procedures maintain structural integrity and avoid catastrophic complications associated with open globe surgery. Corneal transplantation procedures are broadly classified as full-thickness penetrating keratoplasty and partial lamellar corneal surgeries which include anterior lamellar keratoplasty [sperficial anterior lamellar keratoplasty (SALK), automated lamellar therapeutic keratoplasty (ALTK) and deep anterior lamellar keratoplasty (DALK)] and posterior lamellar keratoplasty [Descemet stripping automated endothelial keratoplasty (DSAEK) and Descemet membrane endothelial keratoplasty (DMEK)] broadly.