Descemet Membrane Endothelial Keratoplasty and Bowman Layer Transplantation: An Anatomic Review and Historical Survey.

For nearly a century, the definitive treatment of many corneal dystrophies and ectactic disorders was limited to penetrating keratoplasty, but over the past 2 decades, a surge of surgical innovation has propelled the treatment of many corneal diseases to more targeted approaches with significantly better visual outcomes. Anterior stromal diseases were first changed through endothelial-sparing techniques, such as deep anterior lamellar keratoplasty, but have more recently transitioned to stromal-sparing approaches. Ultraviolet corneal crosslinking strengthens the cornea and halts progression of keratoconus in >90% of cases. Intracorneal ring segment and corneal allogenic ring segment implantation offer methods to flatten ectatic corneas. However, Bowman layer transplantation - inlay and more recently onlay techniques - has shown promise for treating advanced keratoconus and preventing keratoplasty. The advent of endothelial keratoplasty radically changed the treatment of corneal endothelial dysfunction, and Descemet membrane endothelial keratoplasty specifically offers an average postoperative visual acuity of 20/25 (0.8) with only 8.8% of grafts requiring retransplantation in the first 5 years. Here, we review the rapid innovations for surgical treatment of corneal diseases, spanning from endothelial keratoplasty and endothelial regeneration to anterior lamellar keratoplasty and stromal augmentation, highlighting key steps which may be moving us closer to a "postkeratoplasty" world.

Potential benefits of modified corneal tissue grafts for keratoconus: Bowman layer 'inlay' and 'onlay' transplantation, and allogenic tissue ring segments.

PURPOSE OF REVIEW: Keratoconus can be surgically challenging, especially in advanced cases. Classic corneal transplantation techniques, may often be associated with complications. New alternative procedures like isolated Bowman layer transplantation (as a corneal stromal inlay or as a corneal onlay) and corneal allogenic intrastromal ring segments (CAIRS) have recently shown promising results. The aim of this review is to describe the main new surgical developments for treating keratoconus. RECENT FINDINGS: Intrastromal Bowman layer transplantation has recently shown to be effective in halting keratoconus progression and maintaining visual acuity with contact lenses, at least up to 5-7 years postoperatively. Because intrastromal dissection can be challenging, we have recently developed a technique that allows using Bowman layer grafts as an onlay, that is positioned onto the patient's anatomical Bowman layer or anterior stroma, achieving comparable results as with Bowman layer inlay transplantation. CAIRS may also be an effective treatment, improving visual acuity, corneal surface parameters and keratoconus progression. SUMMARY: There are currently some new alternative treatments such as isolated Bowman layer inlay or onlay transplantation and CAIRS, both of which seem effective at treating keratoconus and which may offer a less invasive surgical approach.

Bowman layer transplantation: 5-year results.

PURPOSE: The purpose of this study was to evaluate the 5-year clinical results of isolated Bowman layer (BL) transplantation in the treatment of advanced keratoconus. METHODS: In this prospective, single-center, interventional case series at a tertiary referral center, 20 eyes of 17 patients with advanced keratoconus underwent BL transplantation, i.e. an isolated Bowman layer graft was positioned into a manually dissected mid-stromal pocket. Scheimpflug-based corneal tomography measurements, best corrected spectacle and contact lens visual acuities (BSCVA and BCLVA), endothelial cell density, and complications were evaluated up to 5 years after surgery. RESULTS: Measured simulated and maximum keratometry (Kmean and Kmax) values were stable up to 5 years after surgery (P = .310 and P = .195 for 5 years compared to 1 month follow-up, respectively), following an initial decrease from pre- to 1 month postoperatively (P < .001 each). Mean LogMAR BSCVA remained stable (P > .99), after an initial improvement from pre- to 12 months postoperatively (P = .007). Mean BCLVA did not change from preoperative to 5 years postoperatively (P = .219). During all postoperative follow-ups, mean densitometry values were higher than preoperatively (P < .001). A corneal hydrops occurred in one eye at 4.5 years postoperatively; no other postoperative complications were observed. Kaplan-Meier analysis showed an estimated success rate of 84% at 5 years postoperatively. Endothelial cell density remained stable from before to 5 years after surgery (P = .319). CONCLUSIONS: After early postoperative corneal flattening, topographies were stable up to 5 years after BL transplantation, preserving BCLVA and contact lens tolerance, potentially allowing long term postponement of penetrating or deep anterior lamellar keratoplasty.

Clinical outcome of 500 consecutive cases undergoing Descemet's membrane endothelial keratoplasty.

PURPOSE: To evaluate the clinical outcome of 500 consecutive cases after Descemet's membrane endothelial keratoplasty (DMEK) and the effect of technique standardization. DESIGN: Prospective, interventional case series at a tertiary referral center. PARTICIPANTS: A total of 500 eyes of 393 patients who underwent DMEK for Fuchs' endothelial corneal dystrophy, bullous keratopathy, or previous corneal transplant failure. METHODS: Best-corrected visual acuity (BCVA), endothelial cell density (ECD), pachymetry, and intraoperative and postoperative complications were evaluated before and 1, 3, and 6 months after DMEK. MAIN OUTCOME MEASURES: Comparison between 2 groups (group I: cases 1-250, outcome of "early surgeries" during transition to technique standardization; group II: cases 251-500, outcome of "late surgeries" after technique standardization). RESULTS: At 6 months, 75% of eyes reached a BCVA of ≥20/25 (≥0.8), 41% of eyes achieved ≥20/20 (≥1.0), and 13% of eyes achieved ≥20/18 (≥1.2) (n=418) when excluding eyes with ocular comorbidities (n=57). When including all available eyes at 6 months (n=475), 66% of eyes reached a BCVA of ≥20/25 (≥0.8), and 36% of eyes achieved ≥20/20 (≥1.0). Mean ECD decreased by 37% (±18%) to 1600 (±490) cells/mm2 (n=447) at 6 months (P<0.001). Postoperative pachymetry averaged 525 (±46) µm compared with 667 (±92) µm preoperatively (P<0.001). None of these parameters differed among the 2 groups (P>0.05). (Partial) graft detachment presented in 79 eyes (15.8%), and 26 eyes (5.2%) required a secondary surgery within the first 6 months (re-bubbling in 15, secondary keratoplasty in 11). With technique standardization, the postoperative complication rate decreased from 23.2% to 10% (P<0.001) and the rate of secondary surgeries decreased from 6.8% to 3.6% (P=0.10). CONCLUSIONS: In comparison with earlier endothelial keratoplasty techniques, DMEK may consistently give higher visual outcomes and faster visual rehabilitation. When used for the extended spectrum of endothelial pathologies, DMEK proved feasible with a relatively low risk of complications. Technique standardization may have contributed to a lower graft detachment rate and a relatively low secondary intervention rate. As such, DMEK may become the first choice of treatment in corneal endothelial disease.

Repeat Descemet membrane endothelial keratoplasty after complicated primary Descemet membrane endothelial keratoplasty.

PURPOSE: To describe the clinical outcome and complications of repeat Descemet membrane endothelial keratoplasty (re-DMEK). DESIGN: Retrospective case series study at a tertiary referral center. PARTICIPANTS: From a series of 550 consecutive DMEK surgeries with ≥ 6 months follow-up, 17 eyes underwent re-DMEK for graft detachment after initial DMEK (n = 14) and/or endothelial graft failure (n = 3). The outcomes were compared with an age-matched control group of uncomplicated primary DMEK surgeries. METHODS: The re-DMEK eyes were evaluated for best-corrected visual acuity (BCVA), densitometry, endothelial cell density (ECD), pachymetry, and intraoperative and postoperative complications. MAIN OUTCOME MEASURES: Feasibility and clinical outcome of re-DMEK. RESULTS: In all eyes, re-DMEK was uneventful. At 12 months, 12 of 14 eyes (86%) achieved a BCVA of ≥ 20/40 (≥ 0.5); 8 of 14 eyes (57%) achieved ≥ 20/25 (≥ 0.8), 3 of 14 eyes (21%) achieved ≥ 20/20 (≥ 1.0), and 1 eye (7%) achieved 20/17 (1.2); 5 eyes were fitted with a contact lens. Average donor ECD decreased from 2580 ± 173 cells/mm(2) before to 1390 ± 466 cells/mm(2) at 6 months after surgery, and pachymetry from 703 ± 126 µm to 515 ± 39 µm, respectively. No difference in densitometry could be detected between re-DMEK and control eyes (P = 0.99). Complications after re-DMEK included primary graft failure (n = 1), secondary graft failure (n = 2), graft detachment requiring rebubbling (n = 1), secondary glaucoma (n = 2), cataract (n = 1), and corneal ulcer (n = 1). One eye received tertiary DMEK. CONCLUSIONS: In the management of persistent graft detachment and graft failure after primary DMEK, re-DMEK proved a feasible procedure. Acceptable BCVA may be achieved, albeit lower than after DMEK in virgin eyes, and some cases may benefit from contact lens fitting. Complications after re-DMEK may be better anticipated than after primary DMEK because graft detachment and graft failure tended to recur, suggesting that intrinsic properties of the host eye play a role in graft adherence and graft failure.

Bowman Layer Onlay Grafting as a Minimally Invasive Treatment for the Most Challenging Cases in Keratoconus.

PURPOSE: To analyze the clinical outcomes after Bowman layer (BL) onlay grafting for the treatment of progressive, advanced keratoconus. DESIGN: Prospective, interventional case series. METHODS: Twenty-one eyes underwent BL onlay grafting. After removing the epithelium, a single or double BL graft was "stretched" onto the corneal surface, allowed to dry-in, and a soft bandage lens was placed until the graft was re-epithelialized. Best spectacle- and/or best contact lens-corrected visual acuity (BSCVA/BCLVA), corneal tomography, and postoperative complication rates were analyzed for the total group and 2 subgroups (group 1: preoperative maximum keratometry [Kmax] <69 diopters [D; n = 7); group 2: preoperative Kmax ≥69 D [n = 14]). Follow-up ranged from 6 to 36 months (mean 21 ± 11 months). RESULTS: All 21 surgeries were uneventful. Overall, Kmax changed from 76 ± 12 D preoperatively to 72 ± 9 D at 6 to 36 months postoperatively (P = .015). Kmax decreased by 6 D in group 2 (P = .002) but did not change in group 1. Average BSCVA remained stable for group 1 and improved from preoperatively 0.8 ± 0.4 to 0.4 ± 0.2 logarithm of the minimum angle of resolution postoperatively in group 2 (P = .032); BCLVA remained stable (P > .05). Within the first postoperative weeks, 2 eyes required BL graft repositioning after inadvertent bandage lens removal and 4 eyes underwent BL retransplantation for incomplete re-epithelialization. One eye underwent BL regrafting 12 months postoperatively after traumatic corneal erosion. All eyes showed a completely re-epithelialized graft at the last available follow-up. CONCLUSIONS: BL onlay grafting is a completely extraocular, minimally invasive surgical technique, providing up to -6 D of corneal flattening in eyes with advanced progressive keratoconus, allowing for continued (scleral) contact lens wear and therefore preserving the BCLVA.

Predictive value of optical coherence tomography in graft attachment after Descemet's membrane endothelial keratoplasty.

PURPOSE: To evaluate the predictive value of early anterior segment optical coherence tomography (AS-OCT) on graft adherence or detachment after Descemet's membrane endothelial keratoplasty (DMEK). DESIGN: Retrospective study of prospectively collected data at a tertiary referral center. PARTICIPANTS: A total of 87 eyes of 87 patients of a consecutive series of 142 DMEK surgeries. METHODS: Anterior segment OCT was performed within the first hour after DMEK and at 1 week, 1 month, 3 months, and 6 months, and for each time interval detachments were classified as "none," ≤ 1/3 detachment, >1/3 detachment of the total graft surface area, or "complete" detachment. Throughout the study, no rebubbling procedures were performed. MAIN OUTCOME MEASURES: Graft adherence at various postoperative time intervals. RESULTS: One-hour AS-OCT scans were more accurate at predicting the final 6-month graft adherence status than those at 1 week or 1 month. Grafts showing complete attachment or <1/3 detachment at 1 hour remained stable or improved in 73% of the cases at 1 week, 82% at 1 month, 86% at 3 months, and 90% at 6 months. All grafts attached at 1 week remained attached at 6 months. Graft detachments of >1/3 at 1 hour showed reattachment at 6 months in 25% of the cases, whereas 67.5% of the cases showed a persistent detachment of >1/3 at 6 months and 12.5% showed a complete detachment. CONCLUSIONS: The 1-hour AS-OCT scan showed the best predictive value on 6-month graft adherence status. The combined information of the 1-hour and 1-week AS-OCT scans may facilitate decision making about surgical reintervention after DMEK.

P19-A118†Bowman layer onlay: preparation and transplantation (BLOT).

PURPOSE: With the introduction of Bowman layer onlay transplantation (BLOT), the need for BL transplants increases.In this study, the clinical outcomes of BLOT are described and the results of three different BL graft preparation methods are evaluated: manually (m-BL), femtosecond laser-assisted (fs-BL), and femtosecond laser-assisted followed by excimer laser (fs/ex-BL). METHOD: Twenty-one eyes with advanced progressive keratoconus underwent BLOT with m-BL. Best spectacle- and/or best contact lens-corrected visual acuity (BSCVA/BCLVA), corneal tomography, and complications were recorded. Follow-up ranged from 6-36 months with a mean follow-up time of 21±12 months.To evaluate BL preparation methods, Descemet membrane-denuded donor corneas (n=41) were used (n=2 for m-BL, n=18 for fs-BL and n=21 for fs/ex-BL). For fs-BL, corneas were placed on an artificial anterior chamber and different depth cuts were performed with decreasing decrements starting from 30 µm (diameter 9.0 mm). For fs/ex-BL, a superficial flap of 80 µm was created by the femtosecond laser (FEMTO-LDV Z8, Ziemer). Followed by residual stroma ablation by excimer laser (Schwind Amaris 750S) with increasing increments. Grafts were analyzed visually, and graft thickness regularity was evaluated by histological analysis and Transmission Electron Microscopy (TEM). RESULTS: All twenty-one surgeries could be performed without intraoperative complications. Average maximum keratometry changed from 75.8±12D preoperatively to 72.2±9D at the last available follow-up (n=21, P<0.05), and BSCVA/BCLVA improved. Five patients required a regraft; four of those because of a graft detachment within one week.Evaluation of BL-preparation methods: Fs-BL preparation was successful until 14µm cuts (success rate: 12 out of 14, 86%). Fs/ex-BL graft preparation was most successful after an 80µm cut by femtosecond laser with subsequent 60µm ablation by excimer laser (success rate: 15 out of 21, 71%). After the femtosecond laser cut, traces of the femtosecond laser treatment were visible on the flap. While m-BL showed long protruding stromal fibers, they were shorter in fs-BL and absent in fs/ex-BL. CONCLUSION: BL-onlay grafting may be a feasible surgical technique, providing on average -3D of corneal flattening in eyes with advanced progressive keratoconus, while improving patient's visual acuity.Fs-BL and fs/ex-BL preparation may be faster alternatives to manual BL graft preparation.

Histerocystoplasty: a novel surgical procedure in the rat.

BACKGROUND: Enterocystoplasties are associated to complications. To avoid them, different types of tissue templates have been used to augment the bladder and induce native bladder regeneration. MATERIALS AND METHODS: A novel surgical technique for bladder reconstruction using autologous uterine tissue was evaluated in a rat model. Forty-two female Wistar rats were randomly allocated into three groups: sham-operation hysterocystorrhaphy (n = 12), hysterocystoplasty (n = 18), and control (n = 12). Two weeks after surgery, ultrasound examination of the bladder was performed. At 2, 4, or 6 mo after surgery, the rats were anesthetized and blood and urine samples were taken. They were then euthanized and post-mortem and histologic examination were performed. Ultrasound examination, analytical parameters and weight control, as well as gross and histologic examination were performed in all the operated animals. The statistical analysis was performed using Kruskal-Wallis and the extension of Fisher's exact tests. Significance was set at 5% (P < 0.05). RESULTS: Serum chemistry, blood count and peripheral blood smears, electrolytes, and urinary parameters were all within the normal range for the rat. Histologic sections of the surgically augmented zone between the bladder and uterine horn demonstrated urothelial epithelization, providing adequate coverage of the transition area in 72.22% of the rats that underwent hysterocystoplasty. CONCLUSIONS: The hysterocystoplasty was technically viable in all the cases and proved to be an easy and safe surgical model for bladder reconstruction. All animals were healthy after surgery and all systemic parameters analyzed were within normal physiologic range for the rat.

Long-Term Outcomes of Bowman Layer Inlay Transplantation for the Treatment of Progressive Keratoconus.

PURPOSE: To report long-term clinical outcomes and estimated success rates after Bowman layer (BL) inlay transplantation in eyes treated for progressive keratoconus (KC). METHODS: Thirty-five eyes (29 patients) with progressive KC underwent BL inlay transplantation. Best-corrected spectacle and contact lens visual acuity, Scheimpflug-based corneal tomography [simulated and maximum keratometry (Kmax)], central corneal thickness, thinnest point thickness, complications, and success rate were evaluated up to 8 years postoperatively for the total group and 2 subgroups [group 1: preoperative Kmax > 69 diopter (D) (n = 26); group 2: preoperative Kmax < 69D (n = 9)]. RESULTS: Mean logarithm of the minimum angle of resolution best contact lens-corrected visual acuity for the total group and the 2 subgroups did not change from preoperative up to the last available follow-up (all P > 0.05), whereas best spectacle-corrected visual acuity improved for group 1 ( P = 0.03). Group 1 showed an average Kmax reduction of 7D in the first month ( P < 0.001) with no further changes up to 8 years postoperatively ( P > 0.05), whereas no significant changes were observed in group 2 (all P > 0.05). Postoperative KC progression occurred in 4 eyes (n = 3 group 1, n = 1 group 2) and 1 eye (group 2) underwent retransplantation for unsatisfactory visual performance. Kaplan-Meier analysis showed an estimated success rate of 85% at the 5 to 8 years follow-up in group 1 and of 75% at the 5 to 7 years follow-up for group 2. CONCLUSIONS: BL inlay transplantation stabilized KC in most eyes along with preservation of contact lens tolerance up to 8 years postoperatively and may be a successful treatment option, in particular for eyes with progressive advanced KC (Kmax > 69D).

Acute Hydrops After Bowman Layer Transplantation for Keratoconus May Indicate that Descemet Membrane Rupture Is Secondary to Hydrops.

PURPOSE: The aim of this study was to review the postoperative course and imaging features of 7 eyes that presented with corneal hydrops after Bowman layer (BL) transplantation was performed for advanced keratoconus to determine the potential mechanisms of hydrops formation. METHODS: A retrospective analysis was performed of 7 eyes of 5 patients with advanced keratoconus that underwent midstromal BL transplantation at 2 tertiary referral centers and developed acute corneal hydrops on average 64 (±30) months (range 14-104 months) postoperatively. Corneal tomography and anterior segment optical coherence tomography (AS-OCT) images were reviewed to document the postoperative and posthydrops course. RESULTS: For all eyes, the post-BL transplantation course was uneventful until hydrops development. Despite stable postoperative topographies in 5 of 7 eyes, eyes developed hydrops with typical hypodense areas on AS-OCT that were limited to the stromal layers posterior to the BL graft. With AS-OCT (6/7 eyes), 2 eyes showed a break in Descemet membrane, whereas Descemet membrane was intact across the cornea in 2 eyes; in 2 eyes, the images were inconclusive. All patients admitted to continued eye rubbing, and all but 1 had a clinically significant allergy and/or atopic constitution. Most eyes (5/7) showed a relatively quick (visual) recovery within 1 to 4 months after hydrops. CONCLUSIONS: Hydrops formation in keratoconic corneas after midstromal BL transplantation may indicate that a break in Descemet membrane is secondary to hydrops development (and not vice versa). With a midstromal BL graft in situ limiting hydrops dimensions, resolution of the hydrops seemed relatively quick with recovery to prehydrops visual acuity in most eyes.

Bowman Layer Onlay Graft for Recurrent Corneal Erosions in Map-Dot-Fingerprint Dystrophy.

PURPOSE: The purpose of this study was to describe a case with recurrent corneal erosions who was treated with a Bowman layer (BL) onlay graft. METHOD: BL onlay transplantation was performed. RESULTS: In a 79-year-old female patient who presented with bilateral map-dot-fingerprint dystrophy and a history of recurrent painful corneal erosions, BL onlay grafting was performed to restore the corneal surface. At 1 month postoperatively, the epithelium was smooth over the graft, and until 1.5 years postoperatively, the patients had no complaints and no recurrence of the epithelial corneal erosion. CONCLUSIONS: In the described case, the transplantation of an isolated BL graft as an onlay proved to be an effective treatment for painful chronic recurrent erosions in the context of map-dot-fingerprint dystrophy in a patient who had undergone numerous unsuccessful previous treatments.

Learning Curve in Descemet's Membrane Endothelial Keratoplasty: First Series of 135 Consecutive Cases.

PURPOSE: To evaluate the learning curve in Descemet's membrane endothelial keratoplasty (DMEK) in the management of corneal endothelial disorders. DESIGN: Retrospective, nonrandomized, clinical study at a tertiary referral center. PARTICIPANTS: We included 135 eyes of 118 patients with Fuchs' endothelial dystrophy. METHODS: In a first group of 135 consecutive eyes, a DMEK was performed. To determine the extent of a possible learning curve in DMEK surgery, the whole group was divided into 3 subgroups of 45 patients, to compare clinical outcomes at 1, 3, and 6 months. MAIN OUTCOME MEASURES: Best-corrected visual acuity (BCVA), endothelial cell density (ECD), and intra- and postoperative complications. RESULTS: Among the 3 groups clinical outcomes were similar, with 73% of cases achieving a BCVA of ≥20/25 (≥0.8) and an average ECD of 1747 ± 527 cells/mm², at 6 months. Graft detachment was the main complication and correlated with intraoperative vitreous pressure (P<0.01). The detachment rate declined with experience: In the first 45 cases, a complete or partial graft detachment occurred in 20%, in the second group in 13.3%, and in the third group in 4.4%. Other complications were relatively uncommon: Failure to unfold or position the graft during surgery (0.7%), intraocular hemorrhage (0.7%), primary graft failure (2.2%), air-bubble induced angle closure glaucoma (3%), remnant host Descemet's at the interface (5.9%), and cystoid macular edema (0.7%). Surgeries (partially) performed by an inexperienced surgeon showed a similar clinical outcome and complication rate. CONCLUSIONS: The learning curve in DMEK did not correlate with clinical outcome (BCVA and ECD), but rather to the presence of a functional graft. However, the number of functional grafts (decline in graft detachment rate) increased with surgical experience. FINANCIAL DISCLOSURE(S): Proprietary or commercial disclosures may be found after the references.

New developments in corneal endothelial cell replacement.

Corneal transplantation is currently the most effective treatment to restore corneal clarity in patients with endothelial disorders. Endothelial transplantation, either by Descemet membrane endothelial keratoplasty (DMEK) or by Descemet stripping (automated) endothelial keratoplasty (DS(A)EK), is a surgical approach that replaces diseased Descemet membrane and endothelium with tissue from a healthy donor eye. Its application, however, is limited by the availability of healthy donor tissue. To increase the pool of endothelial grafts, research has focused on developing new treatment options as alternatives to conventional corneal transplantation. These treatment options can be considered as either 'surgery-based', that is tissue-efficient modifications of the current techniques (e.g. Descemet stripping only (DSO)/Descemetorhexis without endothelial keratoplasty (DWEK) and Quarter-DMEK), or 'cell-based' approaches, which rely on in vitro expansion of human corneal endothelial cells (hCEC) (i.e. cultured corneal endothelial cell sheet transplantation and cell injection). In this review, we will focus on the most recent developments in the field of the 'cell-based' approaches. Starting with the description of aspects involved in the isolation of hCEC from donor tissue, we then describe the different natural and bioengineered carriers currently used in endothelial cell sheet transplantation, and finally, we discuss the current 'state of the art' in novel therapeutic approaches such as endothelial cell injection.

Preclinical testing of small diameter Descemet membrane endothelial keratoplasty grafts to increase tissue availability.

In this study, we describe a process of preparing, surgically manipulating, and validating a novel "small diameter" 4mm circular Descemet membrane endothelial keratoplasty (DMEK) graft in vitro. Three small diameter DMEK grafts can be prepared from a single donor endothelium and could, therefore, potentially expand the donor pool. Prior to clinical use, however, we aimed to examine each step of the process to determine the effect on the endothelial cell loss and whether or not cells retained their capacity to migrate uniformly. For this study, circular small diameter grafts, obtained from twelve corneas of ten donors deemed ineligible for transplantation, were included. Small diameter DMEK graft preparation was successful in all cases (n = 36). Endothelial cell density (ECD), determined in the eye bank on seventeen grafts, showed an average decrease from 2413 (±189) cells/mm2 before to 2240 (±413) cells/mm2 after preparation. Twenty-four grafts were used to simulate DMEK-surgery in vitro and were successfully stained with 0.06% trypan blue, loaded into a straight DMEK-injector, unfolded, positioned, and centered within the circular ~ 4mm descemetorhexis. The estimated % area populated by viable cells on the grafts decreased from on average 92 (±3) % before to 78 (±10) % (n = 4) after in vitro surgery. Cells displayed a capacity for uniform cell migration from all edges of the graft (n = 4) when embedded in the 3D hydrogel system. Our data show, that by using an in vitro model of DMEK-surgery it was possible to test the 4mm circular DMEK grafts from eye bank preparation to surgical implantation. The cell loss after in vitro surgery was comparable with the in vivo ECD decline early after DMEK and the capacity of the cells to migrate to potentially cover bare stroma indicates that these small diameter grafts may be a viable clinical option to treat central endothelial disease.

Bowman Layer Onlay Grafting: Proof-of-Concept of a New Technique to Flatten Corneal Curvature and Reduce Progression in Keratoconus.

PURPOSE: The aim of this study was to describe a new surgical technique for flattening the corneal curvature and to reduce progression in eyes with advanced progressive keratoconus (KC) by using Bowman layer (BL) onlay grafting and to report on the preliminary outcomes of this procedure. METHODS: In this prospective interventional case series, 5 patients with advanced progressive KC underwent BL onlay grafting. After removal of the epithelium, a BL graft was placed and "stretched" onto the stroma, and a bandage lens was placed to cover the BL graft. In 1 case, BL onlay grafting could be performed immediately after ultraviolet corneal crosslinking; all other eyes were ineligible for ultraviolet corneal crosslinking. Best spectacle- and/or best contact lens-corrected visual acuity, refraction, biomicroscopy, corneal tomography, anterior segment optical coherence tomography, and complications were recorded at 1 week and at 1, 3, 6, 9, and 12 to 15 months postoperatively. RESULTS: All 5 surgeries could be performed successfully. Average maximum keratometry went from 75 diopters (D) preoperatively to 70 D at 1 year postoperatively. All eyes showed a completely reepithelialized and a well-integrated graft. Best spectacle-corrected visual acuity improved at least 2 Snellen lines (or more) in 3 of 5 cases and best contact lens-corrected visual acuity remained stable, improving by 3 Snellen lines in case 1 at 15 months postoperatively. Satisfaction was high, and all eyes again had full contact lens tolerance. CONCLUSIONS: BL onlay grafting may be a feasible surgical technique, providing up to -5 D of corneal flattening in eyes with advanced KC.

Simple maneuver for unfolding giant retinal tear inverted flap trapped under perfluorocarbon bubble.

Inverted retinal detachments secondary to giant retinal tears are sometimes difficult to unfold with the perfluorocarbon (PFC) bubble even after complete epiretinal dissection due to the tendency of the flap to maintain its inverted configuration. The following maneuver has been performed in two cases. After reducing the PFC bubble volume to the level of the border of the flap, the tip of the same perfluorocarbon injection cannula is used to capture the inverted retinal flap with gentle suction. The flap is lifted and brought centripetally to "cover" the PFC bubble and then released by stopping suction. Then bubble volume can be increased to reapply the entire retina, allowing for continuation of surgery. This simple maneuver allows, in one quick surgical step and without the introduction of new instruments, unfolding of persistently inverted giant retinal tears.

Descemet Membrane Endothelial Keratoplasty: Ten-Year Graft Survival and Clinical Outcomes.

PURPOSE: To evaluate the 10-year graft survival and clinical outcomes of the first case series after Descemet membrane endothelial keratoplasty (DMEK). DESIGN: Retrospective, interventional case series. METHODS: After excluding the very first 25 DMEK eyes that constitute the technique learning curve, the following 100 consecutive primary DMEK eyes (88 patients) were included. Main outcome parameters (survival, best-corrected visual acuity [BCVA], central endothelial cell density [ECD], and central corneal thickness [CCT]) were evaluated up to 10 years postoperatively, and postoperative complications were documented. RESULTS: At 5 and 10 years after DMEK, 68 and 57 of 100 eyes, respectively, were still available for analysis. Of those eyes, 82% and 89% reached a BCVA of ≥20/25 (decimal VA ≥0.8) at 5- and 10 years postoperatively, respectively. Preoperative donor ECD decreased by 59% at 5 years and 68% at 10 years postoperatively. CCT averaged 668 ±74 µm preoperatively and 540 ± 33 µm and 553 ± 43 µm at 5 and 10 years, respectively, after surgery. Within 10 years, 4% of eyes developed allograft rejection, no primary graft failures occurred, and 6% of the eyes developed secondary graft failure. Graft survival probability was 0.83 (95% confidence interval [CI], 0.75-0.92) and 0.79 (95% CI, 0.70-0.88) at 5 and 10 years postoperatively, respectively. CONCLUSIONS: Most eyes that underwent surgery in the pioneering phase of DMEK showed excellent and stable clinical outcomes with low postoperative complication rates and promising graft longevity over the first decade after surgery. This suggests that DMEK may be a safe long-term treatment option for corneal endothelial diseases.

Bowman Layer Onlay Graft for Reducing Fluctuation in Visual Acuity After Previous Radial Keratotomy.

PURPOSE: To describe the clinical outcome of a first patient undergoing Bowman layer (BL) transplantation with an onlay graft to reduce fluctuation in visual acuity and refractive error after previous radial keratotomy (RK) surgery. METHODS: In 2018, a 66-year-old woman presented with complaints of long-standing diurnal fluctuation in best-spectacle corrected visual acuity (BSCVA) after RK in 1983. After the removal of host epithelium, a BL graft was positioned onto the host cornea. BSCVA, Scheimpflug-based corneal tomography, and anterior segment optical coherence tomography were evaluated up to 12 months postoperatively. RESULTS: The surgery and postoperative course were uneventful. After surgery, the subjective complaints of visual fluctuation were reduced from 10 to 3 on a scale from 1 to 10. BSCVA (20/40; 0.5) did not change from preoperative to postoperative. Corneal tomography showed an overall central corneal steepening of 5.9 diopters. Biomicroscopy, Scheimpflug imaging, and anterior segment optical coherence tomography showed a completely epithelialized and well-integrated graft, with some minor epithelial remnants located in the preexisting keratotomy incisions. CONCLUSIONS: BL onlay grafting may have the potential to manage patients with subjective complaints of diurnal fluctuation in visual acuity after previous RK.

In Vitro Evaluation of the Feasibility of Slit-Lamp Nd: YAG Laser Descemetorhexis.

PURPOSE: To evaluate in vitro the feasibility and tissue effects of using a slit-lamp neodymium-doped yttrium aluminum garnet (Nd:YAG) laser to create a central descemetorhexis in human donor corneas. METHODS: Twelve human donor corneas ineligible for transplantation were divided into 2 groups, A and B. Group A: 2 "healthy" corneas, which were used to validate the laser parameters; group B: 10 corneas with endothelial guttae, which were used to perform a 4-mm descemetorhexis. Slit-lamp photography, light microscopy, corneal endothelial microscopy, Scheimpflug imaging, optical coherence tomography (OCT) imaging, and histological staining were performed to visualize the efficacy of slit-lamp Nd:YAG laser removal of Descemet membrane and to assess potential tissue damage to the overlying stroma and peripheral endothelium. RESULTS: In all corneas, an Nd:YAG laser 4-mm central descemetorhexis could be consistently performed. The total energy required ranged from 1143 to 2784 mJ. Side effects such as stromal pitting and corneal swelling were observed. CONCLUSIONS: Creating a central descemetorhexis with a slit-lamp Nd:YAG laser proved feasible in vitro. This new technical approach might open the door to a customized in vivo "descemetorhexis-only" treatment for Fuchs endothelial corneal dystrophy eyes, while avoiding the risks associated with intraocular surgery.