Sutureless, posterior lamellar keratoplasty: a case report of a modified technique

To describe a technique for sutureless, posterior lamellar keratoplasty. The procedure was performed for a case of pseudophakic bullous keratopathy. Through a 5.0-mm, self-sealing scleral tunnel incision, a stromal pocket was dissected across the cornea, just above Descemet's membrane. An 8.5-mm diameter posterior lamellar disc, consisting of posterior stroma, Descemet's membrane, and endothelium, was transplanted without suture fixation. One week after surgery, the best spectacle corrected visual acuity (BSCVA) was 0.8 (20/25), with S -1.5 and C -1.0 x 85 degrees. After 1 year, the posterior transplant was clear and in position, and the BSCVA was 0.8 with S -1.5 and C -1.75 x 80 degrees. Pachymetry measured 0.60 mm. Endothelial cell counts averaged 1390 cells/mm2. Sutureless, posterior lamellar keratoplasty may be an effective new surgical approach for managing corneal endothelial disorder

A technique to excise the descemet membrane from a recipient cornea (descemetorhexis)

To describe a technique for excision of the Descemet membrane (DM) from the recipient eye for preparation of a recipient stromal bed in posterior lamellar keratoplasty. In 10 human eye bank eyes and 3 patients, recipient eyes had a 5.0-mm scleral tunnel incision made extending 1.0 mm into the peripheral cornea at the 12 o'clock surgical position. The anterior chamber was completely filled with air, and a reflective glide was placed through the incision onto the iris, to better visualize DM. A 9.0-mm mark was made onto the corneal epithelium to outline the area from which the Descemet membrane was to be removed. With a custom-made scraper, the DM was then carefully stripped off the posterior stroma by loosening the membrane at the 6 o'clock position and pulling it toward the incision at 12 o'clock. The excised DMs were evaluated by light and electron microscopy. In all recipient eyes, DM could be easily and completely removed from the posterior corneal stroma. Microscopy showed isolated DMs without stromal tissue elements. With the technique described, DM can be excised in a controlled fashion without damaging the posterior corneal stroma, to quickly create a recipient stromal bed before implantation of a donor posterior lamellar disk in posterior lamellar keratoplast

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Reply to: Price Jr., Francis W. and Price, Marianne O. "Correspondence : Spontaneous Corneal Clearance Despite Graft Detachment after Descemet Membrane Endothelial Keratoplasty"2 page(s

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Reply to: Stewart, Rosalind M. K.; Hiscott, Paul S. and Kaye, Stephen B. "Correspondence : Endothelial Migration and New Descemet Membrane after Endothelial Keratoplasty"2 page(s

Optical coherence tomography, Scheimpflug imaging, and slit-lamp biomicroscopy in the early detection of graft detachment after Descemet membrane endothelial keratoplasty

Purpose: To evaluate the efficacy of anterior segment optical coherence tomography (OCT), Scheimpflug imaging, and slit-lamp biomicroscopy in the early detection of a (partial) graft detachment after Descemet membrane endothelial keratoplasty (DMEK). Methods: Anterior segment OCT, Scheimpflug imaging, and slit-lamp biomicroscopy were performed in 120 eyes of 110 patients after DMEK. Results: Seventy-eight eyes showed a normal corneal clearance, and the attached Descemet grafts could not be identified with any of the imaging techniques. Forty-two eyes showed persistent stromal edema in the first postoperative month. In transplanted corneas that (partially) did not clear in the early postoperative period, OCT had an added diagnostic value in 36% of cases (15 of 42 eyes) in visualizing whether the graft was detached and, in particular, to discriminate between a "flat" graft detachment and delayed corneal clearance. In contrast, in the presence of corneal edema, Scheimpflug imaging did not provide more information than slit-lamp biomicroscopy in the detection of a graft detachment. Conclusions: Anterior segment OCT may be an effective tool in the detection of an early graft detachment after DMEK, to determine if secondary surgical intervention is indicated or is to be avoided.7 page(s

Early and late-onset cell migration from peripheral corneal endothelium.

In this study we describe peripheral corneal endothelial cell migration in vitro in the absence and presence of a ROCK-inhibitor. For this study, 21 corneal endothelial graft rims, with attached trabecular meshwork (TM), were prepared from Descemet membrane-endothelial cell sheets by 6.5 mm trepanation. For the initial proof-of-concept, 7 outer graft rims were cultured in a thermo-reversible hydrogel matrix for up to 47 days. To assess the effect of a ROCK-inhibitor, 14 paired outer rims were cultured either with or without ROCK-inhibitor for up to 46 days. At the end of culture, tissue was retrieved from the hydrogel matrix and examined for cell viability and expression of different endothelial cell markers (ZO-1, Na+/K+-ATPase, NCAM, glypican, and vimentin). All cultured rims remained viable and displayed either single regions (n = 5/21) or collective areas (n = 16/21) of cell migration, regardless of the presence or absence of ROCK-inhibition. Migration started after 4±2 days and continued for at least 29 days. The presence of ROCK-inhibitor seemed to contribute to a more regular cell morphology of migrating cells. In addition, 7 outer rims demonstrated a phenotypically distinct late-onset but fast-growing cell population emerging from the area close to the limbus. These cells emerged after 3 weeks of culture and appeared less differentiated compared to other areas of migration. Immunostaining showed that migrated cells maintained the expression patterns of endothelial cell markers. In conclusion, we observed 2 morphologically distinct migrating cell populations with the first type being triggered by a broken physical barrier, which disrupted contact inhibition and the second, late-onset type showing a higher proliferative capacity though appearing less differentiated. This cell subpopulation appeared to be mediated by stimuli other than loss of contact inhibition and ROCK-inhibitor presence. Further exploration of the differences between these cell types may assist in optimizing regenerative treatment options for endothelial diseases

Visual rehabilitation rate after isolated descemet membrane transplantation : Descemet membrane endothelial keratoplasty

Objective: To evaluate visual rehabilitation after Descemet membrane endothelial keratoplasty (DMEK) in the management of corneal endothelial disorders. Methods: In this prospective, nonrandomized, clinical study, DMEK was performed in a first group of 35 consecutive patients with either Fuchs endothelial dystrophy or bullous keratopathy. The Descemet membrane was stripped from the recipient posterior stroma with the anterior chamber completely filled with air. Using a 3.0-mm clear corneal incision, an organ-cultured donor Descemet roll 9 to 10 mm in diameter was inserted into the recipient anterior chamber, positioned on the posterior stroma, and secured by completely filling the anterior chamber with air for 45 to 60 minutes. Resutls: Ten eyes had preexisting ocular disease or an early graft detachment. In the remaining 25 DMEK-treated eyes, best-corrected visual acuity was 20/40 (Snellen notation, 0.5) or more in 18 eyes (72%) within 1 month. At 3 months, best-corrected visual acuity was 20/40 (0.5) or more in 23 of 25 eyes (92%) and 20/25 (0.8) or more in 15 of 25 eyes (60%). Conclusions: In most cases, DMEK results in functional visual rehabilitation within 1 to 3 months. Overall, visual recovery after DMEK may be faster and more complete than with other techniques for (lamellar) keratoplasty for treatment of corneal endothelial disorders.4 page(s

In vitro endothelial cell migration from limbal edge-modified Quarter-DMEK grafts.

Endothelial cell migration plays a crucial role in achieving corneal clearance after corneal transplantation when using smaller-sized endothelial grafts to increase the donor pool. In this study we investigated how different strategies of Quarter-Descemet Membrane Endothelial Keratoplasty (Quarter-DMEK) limbal graft edge modification influence peripheral endothelial cell migration in an in vitro culture environment. For this study, 15 Quarter-DMEK grafts, prepared from 7 corneas deemed ineligible for transplantation but with intact and viable endothelial cells, were embedded in a cooled biocompatible, thermoresponsive matrix for culture. The limbal edge of ten Quarter-DMEK grafts were modified, either by using a small diameter punch or by peripheral radial cuts. All Quarter-DMEK grafts showed substantial collective endothelial cell migration from the radial cut graft edges, as observed by light microscopy at standardized time intervals. Grafts were retrieved from the polymer matrix after the two-week culture for immunohistochemistry analyses of the newly formed cell monolayers; this demonstrated the presence of tightly packed and viable cells that showed higher migratory ability at the leading edge. Peripheral endothelial cell migration, however, was not triggered by increasing cell exposure to free space through surgical modifications of the far periphery. Our data suggest that alterations in the far peripheral area of Quarter-DMEK grafts were insufficient to triggering cell migration from the limbal graft edge. This may be due to transient-amplifying cells that reside in the far periphery and which lack cytokinetic directional cues. Understanding the migration capacity of the peripheral endothelium could unlock cells' therapeutic potential which are, at present, routinely discarded from transplantation. Encouraging peripheral cell migration may also improve clinical outcomes from Quarter-DMEK, but a more effective solution is required prior to clinical implementation of modified grafts

Refractive change and stability after Descemet membrane endothelial keratoplasty : effect of corneal dehydration-induced hyperopic shift on intraocular lens power calculation

Purpose: To determine the refractive change and stability of the transplanted cornea after Descemet membrane endothelial keratoplasty (DMEK) through a 3.0 mm clear corneal incision. Setting: Tertiary referral center. Design: Cohort study. Methods: Subjective and objective refractive data from pseudophakic eyes were obtained before and 3 and 6 months after DMEK. Results: The study comprised 50 eyes, 7 were phakic and 43 pseudophakic. Six months postoperatively, the corrected distance visual acuity was 20/25 (0.8) or better in 38 eyes (74%). The mean increase in spherical equivalent at 6 months (N = 50) was +0.32 diopter (D) ± 1.01 D (SD) (P=.0304) and in refractive cylinder, -0.48 ± 1.02 D (P=.001). Although Scheimpflug imaging showed a stable anterior corneal curvature, the posterior curvature increased from 5.50 ± 0.5 D preoperatively to 6.40 ± 0.4 D at 6 months and pachymetry decreased from 672 ± 82 μm to 540 ± 59 μm, respectively (both N = 32) (both P=.000). Conclusions: After DMEK, a slight preoperative to postoperative refractive change and stabilization at 3 months occurred that may induce a hyperopic shift that was not the result of the negative lenticule effect of DSEK/DSAEK. Thus, in DMEK, the hyperopic shift may result from a reversal of a preceding myopic shift induced by stromal swelling in endothelial disease. If so, normal intraocular power nomograms apply for cataract surgery before or during DMEK.10 page(s

Spontaneous corneal clearance despite graft detachment in Descemet membrane endothelial keratoplasty

Purpose: To describe spontaneous recovery of corneal transparency in 2 cases with nearly complete graft detachment after Descemet membrane endothelial keratoplasty (DMEK). Design: Case series. Methods: In 2 patients with Fuchs endothelial dystrophy, DMEK was performed. Through a 3-mm clear corneal tunnel incision, the recipient Descemet membrane and its endothelium was stripped off from the posterior stroma. A 9.5-mm diameter organ-cultured Descemet roll was inserted into a recipient anterior chamber, positioned onto the posterior stroma, and secured by a complete air filling of the anterior chamber for 45 minutes. Results: At 1 month after uneventful DMEK, both transplanted corneas showed decompensation attributable to subtotal graft detachment. Unexpectedly, corneal transparency improved spontaneously, and at 3 months, both transplanted corneas had a normal pachymetry, despite persistent graft detachment. The patients' visual acuities improved to 20/50 (0.4) and 20/25 (0.8) at 3 months to 20/28 (0.7) and 20/20 (1.0), respectively at 9 months. Conclusions: Corneal clearance in the presence of a detached DMEK graft is not consistent with the current concept of endothelial keratoplasty, which requires an (attached) donor endothelial cell layer at the recipient posterior corneal surface. Endothelial transfer, migration, regeneration, or a combination thereof from either the donor or the recipient may explain the visual recovery. These observations suggest that a review of our approach to endothelial keratoplasty and the management of corneal endothelial disorders may be warranted.9 page(s