Effect of Six-Month Postoperative Endothelial Cell Density on Graft Survival after Descemet Membrane Endothelial Keratoplasty.

PURPOSE: To analyze if 6-month endothelial cell density (ECD) affects long-term ECD outcome and graft survival 5 years after Descemet membrane endothelial keratoplasty (DMEK) in eyes with Fuchs endothelial corneal dystrophy (FECD). DESIGN: Retrospective cohort study. PARTICIPANTS: A total of 585 DMEK eyes were included. The study group was divided into 4 groups based on 6-month ECD quartiles: group 1 (n = 146) with 313 to 1245 cells/mm2, group 2 (n = 148) with 1246 to 1610 cells/mm2, group 3 (n = 145) with 1611 to 1938 cells/mm2, and group 4 (n = 146) with 1939 to 2760 cells/mm2. Group 1 was further split into subgroups 1a (n = 36) with 6-month ECD of ≤828 cells/mm2, 1b (n = 37) with 829 to 1023 cells/mm2, 1c (n = 37) with 1024 to 1140 cells/mm2, and 1d (n = 36) 1141 to 1245 cells/mm2. METHODS: Descemet membrane endothelial keratoplasty. MAIN OUTCOME MEASURES: Long-term ECD, graft survival, and postoperative complication rates. RESULTS: For group 1, 6-month ECD decreased from 951 (±233) cells/mm2 (n = 146) to 735 (±216) cells/mm2 (n = 99) at 5 years postoperatively. Group 1 graft survival probability was 0.95 (95% confidence interval [CI], 0.91-0.99] at 5 years postoperatively, which was lower than for groups 2 to 4 (P = 0.001). Five-year graft survival in subgroup 1a was 0.79 (95% CI, 0.67-0.94), which was lower than in subgroups 1b to 1d (P = 0.001). Preoperative ECD did not influence graft survival (P = 0.400), and higher 6-month ECD values were associated with lower graft failure rates (hazard ratio, 0.994; 95% CI, 0.99-1.00; P = 0.001). CONCLUSIONS: Six-month ECD is associated with DMEK graft survival. High early cell loss after DMEK negatively affects long-term ECD outcome and graft survival. Grafts in the lowest 6-month ECD subgroup (≤828 cells/mm2) are at higher risk of failure within 5 years after DMEK. To ensure sufficiently high 6-month ECD, preoperative graft quality assessment should be optimized, and cellular stress induced to the graft should be minimized. Additionally, developing therapeutic options for the treatment of low postoperative ECD could further improve DMEK graft longevity.

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.

The influence of preparation and storage time on endothelial cells in Quarter-Descemet membrane endothelial keratoplasty (Quarter-DMEK) grafts in vitro.

Quarter-Descemet membrane endothelial keratoplasty (Quarter-DMEK) has been introduced as a modification of the standard DMEK technique to increase the pool of endothelial grafts. In this study, we evaluated in vitro changes in endothelial cell distribution, viability and morphology of Quarter-DMEK grafts when stored in organ-culture medium. Quarter-DMEK grafts were prepared from 5 corneas and stored in organ-culture medium for 4, 7 and 11 days. Endothelial cell re-distribution was investigated by light microscopy, cell viability by a Calcein-AM assay, and expression of endothelial and non-endothelial markers by immunohistochemistry. Three standard DMEK-grafts were used as controls. After preparation, all Quarter-DMEK grafts showed a band with no viable endothelial cells along the radial cut graft edges [average width 190 (± 20) µm]. Endothelial cell density in the central graft area decreased by 12%, 23% and 26% after 4, 7, and 11 days of storage, respectively. At the same time, empty bands along the cut edges were re-populated and some cells migrated to the stromal side of the Descemet membrane (DM). These cells showed an altered phenotype, as indicated by expression of migration marker CD73 and fibroblast marker αSMA. Majority of migration occurred within the first 4 days of storage. Our data suggest that endothelial cells on Quarter-DMEK grafts re-distribute during organ-culture storage to re-populate preparation-induced empty bands and after re-distribution, cells may show further migration to the stromal DM side during storage.

Update on Bowman layer transplantation.

PURPOSE OF REVIEW: Bowman layer transplantation is a novel technique that may stabilize progressive ectatic corneal changes in eyes with keratoconus, which are too steep or too thin for ultraviolet corneal crosslinking or intracorneal ring segments. In this way, patients can maintain stable vision with contact lenses, and avoid or postpone more invasive corneal transplants, such as penetrating keratoplasty or deep anterior lamellar keratoplasty. This review aims to summarize the currently available literature on Bowman layer transplantation. RECENT FINDINGS: Bowman layer transplantation seems to be a promising, minimally invasive procedure for managing advanced keratoconus with a reported 5-year success rate of 84%. The procedure allows patients to maintain acceptable visual acuity with glasses or contact lens correction. Although graft preparation and surgical technique can be challenging, adaptation of technologies, such as femtosecond laser and intraoperative anterior segment optical coherence tomography, may help overcome these barriers to enable Bowman layer transplantation to become a more widely adopted procedure. SUMMARY: Bowman layer transplantation may offer an alternative, less invasive treatment option for eyes with advanced, progressive keratoconus.

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.

Histopathology of Failed Descemet Membrane Endothelial Transfer.

OBJECTIVES: To describe the postmortem histologic features after an unsuccessful Descemet membrane endothelial transfer (DMET) and assess any potential clinical implications. METHODS: Postmortem, an eye from a patient who previously underwent unsuccessful DMET for pseudophakic bullous keratopathy (PPBK) was harvested and processed for morphologic evaluation. RESULTS: Clinically and histologically, the host cornea showed evidence of diffuse stromal edema. Although the edges of the surgical descemetorhexis were well visualized, there was no evidence of endothelial migration or repopulation of the posterior stroma from any direction. A multilayered, retrocorneal membrane was present that appeared to originate from the trabecular meshwork. CONCLUSIONS: Descemet membrane endothelial transfer and "descemetorhexis alone" may be insufficient treatment for eyes operated on for PPBK, that is, eyes with a significantly depleted or dysfunctional endothelium.

Descemet membrane endothelial keratoplasty and refractive surgery.

PURPOSE OF REVIEW: Descemet membrane endothelial keratoplasty (DMEK) has become a first-line treatment in corneal endothelial diseases because of its exceptional clinical outcomes and low complication rates. Because of its improved refractive predictability, DMEK is now also considered for managing cases with endothelial decompensation following previous refractive procedures, or in combination with those. This article reviews the clinical outcomes in these cases and discusses the possibility of refractive interventions following DMEK. RECENT FINDINGS: DMEK has been successfully performed in eyes after laser in-situ keratomileusis, eyes after anterior chamber intraocular lens (IOL) implantation and aphakic eyes. Often, DMEK is combined with cataract surgery (triple-DMEK). Initial reports on reducing the refractive cylinder by toric IOL implantation are available. Although there are some reports on phacoemulsification and IOL implantation after phakic DMEK, reports on laser refractive procedures following DMEK are lacking. SUMMARY: In contrast to earlier keratoplasty techniques, DMEK induces on average only mild refractive shifts owing to the 'natural' restoration of the cornea. As such, DMEK may be ideal in managing corneal decompensation in refractive patients. However, further studies are required to assess the safety and efficacy of DMEK after refractive treatment and of refractive procedures following DMEK.

Histopathologic Features of Descemet Membrane Endothelial Keratoplasty Graft Remnants, Folds, and Detachments.

PURPOSE: To describe the histologic features of postmortem eyes after Descemet membrane endothelial keratoplasty (DMEK) and their potential clinical implications. DESIGN: Histopathologic study. PARTICIPANTS: Eleven postmortem DMEK corneas of 8 patients who underwent surgery for Fuchs endothelial dystrophy, with an average postoperative time of 4±1.9 years (range, 7 months-6.5 years). METHODS: Eleven corneas transplanted with a DMEK graft were procured after death and processed for light microscopy evaluation. MAIN OUTCOME MEASURES: Histologic findings at the donor-host interface and at the host edge. RESULTS: Of the 11 corneas available for analysis, 9 showed normal anatomic features in the corneal center; that is, the donor-host interface resembled that of a virgin eye. One eye also had an anatomically normal periphery, but the remaining 10 eyes showed specific abnormalities in the periphery. Nine demonstrated overlapping of the DMEK graft onto the host edge of the descemetorhexis (and in 6 of these, the overlapping tissue showed a contracted inward fold at its peripheral edge with scar tissue); 1 eye showed a dense, acellular scar overlying a portion of the DMEK graft that clinically had shown a detachment followed by spontaneous adherence; 3 eyes showed subtle graft folds with scar tissue anteriorly; in 2 eyes (of the same patient), the anterior banded layer of the host Descemet membrane (DM) was still in situ across the cornea (both of these eyes had required rebubbling); and 2 eyes showed host DM remnants within the corneolimbal tunnel incision that may have interfered with incisional wound healing. CONCLUSION: Incomplete host DM removal may relate to postoperative DMEK graft detachment and wound instability. Graft detachments may reattach with interface scarring. Rebubbling procedures may be performed within 4 to 6 weeks, before portions of the detached graft scar. Subtle DMEK graft folds may explain subjective reports of monocular diplopia.

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.

Bowman layer transplantation to reduce and stabilize progressive, advanced keratoconus.

OBJECTIVE: To evaluate the clinical outcome of mid-stromal isolated Bowman layer transplantation, a new surgical technique to reduce and stabilize ectasia in eyes with advanced keratoconus, to postpone penetrating keratoplasty or deep anterior lamellar keratoplasty, and to enable continued daily contact lens wear. DESIGN: Prospective, nonrandomized cohort study at a tertiary referral center. PARTICIPANTS: Twenty-two eyes of 19 patients with progressive, advanced keratoconus not eligible for ultraviolet cross-linking. INTERVENTIONS: The mid-stroma was manually dissected and an isolated donor Bowman layer was positioned within the stromal pocket. MAIN OUTCOME MEASURES: Before and up to 36 months after surgery (mean follow-up, 21±7 months), best spectacle-corrected visual acuity (BSCVA), best contact lens-corrected visual acuity (BCLVA), Scheimpflug-based corneal tomography measurements, endothelial cell density, biomicroscopy, refraction, and intraoperative and postoperative complications were recorded. RESULTS: Two surgeries were complicated by an intraoperative perforation of Descemet membrane; no other intraoperative or postoperative complications were observed. Maximum keratometry decreased on average from 77.2±6.2 diopters (D) to 69.2±3.7 D (P < 0.001) at 1 month after surgery and remained stable thereafter (P ≥ 0.072). Mean BSCVA improved from 1.27±0.44 logarithm of the minimum angle of resolution units before surgery to 0.90±0.30 logarithm of the minimum angle of resolution units 12 months after surgery (P < 0.001), whereas BCLVA remained stable (P = 0.105). Mean thinnest-point pachymetry increased from 332±59 µm before surgery to 360±50 µm at the latest follow-up (P = 0.012), and no change in endothelial cell density was found (P = 0.355). CONCLUSIONS: With isolated Bowman layer transplantation, reduction and stabilization of corneal ectasia was achieved in eyes with progressive, advanced keratoconus. Given the low risk for complications, the procedure may be performed to postpone penetrating or deep anterior lamellar keratoplasty.

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.

One year outcome of hemi-Descemet membrane endothelial keratoplasty.

PURPOSE: To evaluate the 1-year clinical outcome after semi-circular Descemet membrane endothelial keratoplasty (hemi-DMEK) in a first case series. METHODS: In three eyes of three patients with Fuchs endothelial dystrophy, best corrected visual acuity (BCVA), endothelial cell density (ECD), pachymetry, and intra- and postoperative complications were evaluated after transplantation of a semi-circular ~12 mm diameter Descemet graft (hemi-DMEK graft). RESULTS: All corneas cleared within 6 months and showed a stable pachymetry thereafter (527, 535, and 490 µm, respectively). Compared to preoperative measurements, average central ECDs dropped by 51 % (56, 39, and 59 %, respectively) at 3 months, 53 % (57, 38, and 63 %, respectively) at 6 months, and 59 % (60, 47, and 71 %, respectively) at 12 months. Denuded stromal areas adjacent to the hemi-DMEK graft cleared and at 12 months peripheral ECD counts ranged from 724 to 1051 cells/mm(2). At 12 months, BCVA was 20/22 (0.9), 20/40 (0.5, amblyopic eye) and 20/17 (1.2). No postoperative complications occurred throughout the study period. CONCLUSIONS: Hemi-DMEK may provide visual outcomes similar to those in standard DMEK at the 1-year postoperative mark. If also graft survival and complication rates prove to be similar, hemi-DMEK could become the next step in endothelial keratoplasty, owing to its potential to double the yield of transplants from the same donor pool (two hemi-DMEK grafts can be prepared from one donor cornea).

Dehydration of corneal anterior donor tissue with polyethylene glycol (PEG)-enriched media.

Anterior donor grafts (including scleral rim, without Descemet membrane) increase in thickness and become hazy upon storage in organ culture (OC) medium. Transfer of these grafts to standard dehydration media just before transplantation does not reduce their thickness to normal. Therefore, we assessed the efficacy of different media enriched with polyethylene glycol (PEG) as dehydrating agents for organ-cultured anterior donor grafts. Grafts were harvested and stored in the commercial OC medium 'Max' (without dextran) for 1 week, and subsequently dehydrated in the standard commercial dehydration medium 'Jet' (with dextran) supplemented with 4-20% PEG3350, or 'Max' supplemented with 20% PEG6000 and PEG20.000, or 5-20% PEG35.000. Central corneal thickness (CCT), as assessed by anterior segment-optical coherence tomography, and transparency were evaluated before, and at 1, 4 and 7 days of dehydration. Transfer of grafts after 1 week of OC (average 1,200 µm) to 'Jet' supplemented with PEG3350 revealed a concentration-dependent effect of dehydration; CCT was restored to normal (500-600 µm) when 10% PEG3350 was added. However, transparency was only temporarily restored; after 1 day, the grafts turned hazy. In contrast, grafts transferred to 'Max' supplemented with 20% PEG35.000 were transparent throughout the evaluation period, but were dehydrated to beyond normal levels (average 300 µm). 'Max' supplemented with 5% PEG35.000 dehydrated grafts to normal values and restored transparency throughout. Thus, dehydration of anterior donor grafts prior to surgery in dextran-free OC medium supplemented with 5% PEG35.000 reduces graft thickness to normal and may facilitate anterior keratoplasty procedures.

Descemet membrane endothelial transfer.

PURPOSE OF REVIEW: To elaborate on the recent concept of Descemet membrane endothelial transfer (DMET) and to explore the concepts that underpin its success through reviewing the key articles that have challenged our current understanding of corneal endothelial cell behavior. RECENT FINDINGS: DMET challenges the paradigm that complete graft-host apposition is required for successful corneal clearance in endothelial keratoplasty. It offers the promise of a simpler procedure to restore corneal clarity. Its success may lie in the ability of endothelial cells to migrate and proliferate. Endothelial host cells have been found in isolation and at disparate locations among donor cells within the corneal buttons of patients who have had a penetrating keratoplasty. New evidence for the continued slow proliferation of endothelial cells from the corneal periphery throughout life comes from the microanatomy of the peripheral cornea, and the demonstration of stem cell markers and markers of DNA synthesis in this area. SUMMARY: DMET offers us a tantalizing taste of a simpler way of treating corneal endothelial disease by harnessing the ability of corneal endothelial cells to migrate and proliferate. An understanding of these processes will be the key stepping stone to developing future treatments for corneal endothelial disease.

How Would Nature See Our Corneal Triumphs? The LXXIX Edward Jackson Lecture.

PURPOSE: To describe discrepancies between clinical observation and current teachings in corneal endothelial disease, particularly in Fuchs endothelial dystrophy and its potential association with primary open angle glaucoma. DESIGN: Perspective. METHODS: A perspective is presented on Fuchs dystrophy, a disorder that commonly presents with a compromised endothelium but minimal stromal edema, indicating that the corneal imbibition pressure is relatively "too high." RESULTS: The discrepancy between the relative lack of stromal edema in the absence of an endothelial cell layer cannot be explained by the current theories involving a circulatory pumping mechanism over the endothelial cell layer, but may point to the following: (1) secondary involvement of the corneal endothelium in Fuchs dystrophy; (2) separate hydration systems for maintaining the imbibition pressure (vertical static hydration) and corneal nutrition (horizontal dynamic hydration); (3) the cornea as net contributor of aqueous humor; (4) a close relationship between the corneal imbibition and intraocular pressure, with potentially a shared regulatory system; and (5) a potential steroid-type hormone dependency of this regulatory system. CONCLUSIONS: Clinical observation shows that the stromal imbibition pressure is "too high" in Fuchs endothelial dystrophy, indicating that it may not primarily be an endothelial disease, but a type of "corneal glaucoma."

Corneal Guttae After Descemet Membrane Endothelial Keratoplasty.

PURPOSE: The aim of this study was to report on the occurrence of corneal guttae after Descemet membrane endothelial keratoplasty (DMEK). METHODS: In this retrospective case series, 13 eyes of 13 patients who underwent DMEK at 2 tertiary referral centers between 2007 and 2021 (average available follow-up 73 ± 52 months, range 18-174 months) and showed corneal guttae during postoperative examinations were included. Eye bank images were retrospectively reviewed. RESULTS: Occurrence of guttae was observed by specular microscopy in 13 eyes. In 11 cases, presence of guttae was confirmed by confocal microscopy and in 1 case by histology. Five eyes showed an increase in guttae density during the postoperative course. Surgery indications were Fuchs endothelial corneal dystrophy (n = 11), pseudophakic bullous keratopathy (n = 1), and DMEK graft failure after allograft rejection (n = 1); the latter eye had shown no signs of guttae after primary DMEK. Two eyes with guttae required a repeat DMEK due to graft failure. At the last available follow-up, all 11 remaining eyes had clear corneas and 10 eyes had a best-corrected visual acuity of ≥0.9 (decimal). During donor cornea processing in the eye bank, no guttae were observed on the donor tissue. CONCLUSIONS: Corneal guttae can occur after DMEK including in eyes operated for indications other than Fuchs endothelial corneal dystrophy and most likely guttae were present on the donor graft but were not detectable by routine slit-lamp and light microscopy evaluation in the eye bank. Postoperative guttae density varies among patients and especially small isolated guttae do not seem to affect clinical outcomes.

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.

Dyes for Eyes™: hydrodynamics, biocompatibility and efficacy of 'heavy' (dual) dyes for chromovitrectomy.

As epiretinal membranes (ERMs), the internal limiting membrane (ILM) and the vitreous cortex are essentially transparent tissues, or translucent structures, nontraumatic removal may be challenging in various types of macular surgery. Vital dyes stain these thin tissues, thus allowing for better visualization of these structures during vitrectomy and selective 'membrane peeling' from the underlying retina. To avoid swirling of the dye within the fluid-filled vitreous cavity, and to better target the dye onto the macula, a fluid-air exchange is commonly performed. However, this may jeopardize visualization of the macula during peeling due to clouding of the posterior lens capsule, and may lead to postoperative visual field defects. Recently, a new dye solution for staining the ERM and ILM simultaneously has been developed that circumvents the need for fluid-air exchange, i.e. MembraneBlue-Dual™. This paper will focus on the hydrodynamics and biocompatibility of this 'heavy' dual dye and its efficacy for staining of the ILM and/or ERMs during posterior segment surgery in a multicenter clinical setting.